Note: Descriptions are shown in the official language in which they were submitted.
'' l
WO 95/06416 pCT/US94109698
T~"~'E '~'~''~'~" , r ~,~~
1
IO~~ND APPARATUS FOR PRQC~,$SING FOOD P~QD~,CTS
Background of the Invention
The invention relates to a method and apparatus
for processing foodstuffs; more particularly, this
invention relates to methods and apparatus for processing
rice to achieve a quick-cooking rice.
Mankind is continually searching for new and
better methods of cooking cereal grains, vegetables and
other foodstuffs. In large scale commercial operations,
the cooking of foodstuffs requires ;special apparatus and
specially adapted cooking methods tlhat will provide a
uniform and desirable food product 'while at the same time
handling large quantities of foods.
In the cooking of certain starch-containing foods
such as vegetables and cereal grains, several problems
are encountered. First, the food granules must be moved
from storage tanks to processing vessels, and in some
cases to holding tanks or cooking vessels, and then they
may be distributed to dryers to remove water from the
food granules. The physical transport of the food
granules during such processing must be well regulated
and maintained to achieve a desirable flow of food
particles through the processing system from one
processing step to another, without undesirable clumping
or aggregation of food granules. ...
In certain cases the physical handling and heat
applied to grains during cooking is designed to result in
physical or chemical changes to the starch or other
molecules that are contained in the food stock itself.
For example, in the cooking of cereal grains, such as
rice, the goal is to gelatinize the starches in the
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grain. In such a process, loose starch molecules may be
leached out of the food granules or the starch molecules
may be ruptured as a result of handling or processing.
If that occurs, then cooking processes may tend to glue
together the granules, slowing advancement of the food
product through the processing system. This "gluing"
problem is particularly troublesome in the cooking of
rice and, if allowed to proceed unabated, will cause the
surface of rice particles to stick together, causing
i0 large globules to form, making further transport and
processing of the rice impractical, if not impossible.
In the past, the problem of "gluing" of food
granules by the release or rupture of starch molecules
could be controlled, at least to a limited degree, by
using large amounts of fluid in transporting the food
through the processing machinery, cookers, conduits, and
the like. Typically, water is used as a transport fluid,
and large amounts of water tend to dilute the "glue"
(free hydrated starch,, thereby minimizing the adverse
effect of free starch. By using large amounts of water,
cereal grains may be processed without the undesirable
globules forming to slow the transport of the grains
through processing, equipment. However, such use of water
to dilute this gluing effect results in spent process
water with large amounts of free starch which must be
discarded or further processed such as by water
treatment.
Unfortunately, many communities have greatly
increased the fees that commercial users must pay for
water in such food processing operations. As such, the
processing of food wherein large amounts of water are
required has become extremely expensive in these
communities, and newer and better methods of transporting
and cooking food in a processing system, while using less
water, are highly desirable.
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Also, in the past, water used in a food processing
system for transport of food has been discarded as waste
water at the point in the processing after which the
water is no la:-:~er needed for transport of the food.
However, recent environmental regulations have greatly
r
curtailed the amount of waste water and waste materials
that may be disposed of by food processing facility.
Moreover, many public utilities and water companies
charge corporate water consumers not only on the basis of
the amount of water consumed, but also on the basis of
the number of gallons of waste water that is discharged
back into the public sewer system. Therefore, it is
desirable to limit the amount of waste water that is
produced by a food processing plant.
Additionally, the greater ttte amount of water used
in commercial processing, the greater is the amount of
heat energy that must be applied to reach a desirable
-temperature level. If less water is utilized in a batch
processing system, substantial savings in power
consumption can be achieved. A batch processing system
may, therefore, operate at a lower cost per pound of food
processed.
Commercial rice cooking methods consume and
excrete very large amounts of water. For example, in the
commercial caoking of one cup of rice, prior methods
required as much as a 20:1 ratio of water used to rice
produced pursuant to the processing method. A great
advantage in food processing would be a cooking method
that allows food granules, such as rice, to be cooked
with a ratio of water consumption to food production of
as little as 2:1 or perhaps even.less.
Another problem in the food industry is the
production of a uniform final product, especially in high
production batch or continuous processes. For example,
cooking cereal grains in a uniform manner so that each
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grain receives substantially identical conditions during
cooking presents a challenge.
The challenge arises because numerous variables
exist in processing and because of the difficulty in
exposing each grain to-the same overall history of
cooking conditions. The first variable is the,amount of
heat applied.: The greater the amount of heat applied,
the greater the gelatinization of starch ~rithin the
grainy and the-quicker the rice will cook. Furthermore,
an increase in the pressure during the cooking of rice
will increase the rate at which the starch is
gelatinized, and therefore, it will' speed the,cooking of
the rice: If the rate of gelatinization of the rice is
too high, or if the pressure and temperature conditions
are not optimum during the cooking and drying of the
rice, the individual =gains may be physically harmed by
the formation of small pockets of air or dead; space
within the grain itself: These pocketscaus~ the rice to
become brittle after it is dried, resulting in an
inferior product that consumers find undesirable.
Accordingly, what has been needed in the industry
is a cooking apparatus and method that will provide for
the uniform cooking of the food granules in a continuous
processing system without using:or excreting excess
water; and while avoiding the gluing ogether of the food
granules:
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;~ummarv of ~~e Inv~nt,~
The present invention comprises a method of
processing rice to prepare the rice far packaging,
including the sequential steps of presteaming the rice to
cause the rice to absorb moisture, steeping the rice in
water to further process the rice and to cause the rice
to absorb~further moisture, steam cooking the rice
causing the rice to absorb further moisture, and drying
the rice in preparation for packaging the rice.
In another aspect of the inverrtion, the step of
pzewashing the rice prior to the presteaming step is
accomplished.
In another aspect of the invention, a method is
presented wherein at least a portion of any excess water
enters the cooking step and is recirculated for reuse in
the overall process.
In another aspect of the invention, a method of
processing cereal grains is disclosed, comprising
presteaming the cereal grains, steam cooking the cereal
grains, and drying the cereal grains. Further, the step
of prewashing the cereal grains prior. to presteaming is
presented, and another method further includes the step
of steeping the cereal grains after presteaming.
In another aspect of the invention, the cereal
grains are conditioned by application of chemical
additives. In some cases, the cereal grains are
postconditioned after cooking by application of a gas to
the cereal grains,
In one aspect of the invention, an apparatus for
processing food produets is shown, including a conveying
means, wherein the conveying means is adapted for
transporting faod products in the processing of the
products. In that case, steeping tanks are adapted for
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presoaking uncooked food products, and water
recirculation means, wherein water or steam is applied to
food products and then recirculated, is presented. The
amount of water consumed and excreted in processing food
products being minimized, said water provides for the
dilution of food products during processing to facilitate
movement of food products among processing apparatus, and
to avoid reaching the glue point of said food products,
further Wherein water is reabsorbed and recirculated by
food products in said steeping tanks. Further, a steam
cooker for cooking food products is provided wherein the
cooker transmits water or steam to the food products
during cooking, and the apparatus also includes a drying
means.
In another aspect of the invention, an apparatus
is provided wherein the drying means comprises a rotary
dryer, wherein the food products are conveyed to the
rotary dryer, and reducing the water content of the food
products to prepare the food products for packaging, said
rotary dryer comprising a rotating barrel, said rotating
barrel being adapted for agitation of the food products,
the rotary dryer further comprising a heat source for
reducing the water content of the food products using
heated air. A portion of the excess water removed from
the food products is recirculated back and reabsorbed by
uncooked food products.
In another aspect of the invention, a'method of
processing food granules comprises the steps of
presteaming uncooked food granules, steeping the uncooked
food granules by soaking them in heated water, cooking
the food granules, wherein the food granules are cooked
by application of heat and water in a steam cooker, and
performing the above steps by minimizing the amount of
water consumed. Further, the method may include
minimizing the amount of Water excreted during processing
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of the food granules by subjecting the food granules to
only about as much moisture as they can absorb in that
particular step. Further, at least a portion of any
excess water is provided to the food granules during
performance of the steps to be recirculated and reused in
the overall process.
Advantages of the present inmention include a
reduction in the amount of water that is used in the
process, as a result of efficient use of water. In
particular, water is used in quantities roughly
equivalent to the amount of water that can be absorbed by
the rice grains at that point in the process. A
corresponding reduction in the expenses associated with
purchasing and disposing of water is also an advantage of
this invention. Energy costs are lowered and utility
costs are more reasonable using the process shown herein.
Further, a high clarity of water is provided at
the end of the cooking process, lending to the reuse of
the water from that point in the process for other steps,
as a result of proper presteaming and the use of proper
Water volumes and cooking temperatures.
One of the greatest advantages of this invention
is the avoidance of gluing conditions in the overall
process to assure efficient transport of the food
product. Uniform cooking of individual rice grains is
one advantage, and as a result of the overall process,
high quality rice is produced. Efficient, uniform and
variable drying of the rice grains is provided.
Brief Description of the Drawing
FIG. 1 is a perspective view of the overall food
processing system;
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FIG. 2 is a flow chart showing the movement of the
food granules among the various processing steps of the
present invention;
FIG. ZA is a perspective view of the preferred
embodiment of the steam cooker of the present invention;
FIG. 2B provides a cross-sectional view of the
preferred steam cooker of the present invention;
FIG. 2C provides a detailed view of the shutters
contained within the preferred steam cooker of the
present invention (the steam cooker disclosed in FIGS. 2A
and 2B);
FIG. 3 is a perspective view of a first alternate
embodiment of the steam cooker of the present invention;
FIG. 4 provides an exploded, detailed view of the
interior of the alternate embodiment of the steam cooker
shown in FIG. 3;
FIG. 5 discloses a cross-sectional view of the
steam cooker shown in FIGS. 3 and 4;
FIG. E is a perspective view of another alternate
embodiment of a steam cooker of the present invention;
FIG. 7 is a longitudinally exploded view of an
alternative embodiment of a steam cooker as shown in FIG~
6;
FIG. 8 is a closeup view of the arrangement of one
Z5 of the cooking chambers within the steam cooker shown in
FIGS. 6 and ?;
FIG. 9 is a perspective view of yet another
embodiment of the steam cooker of the present invention;
FIG. 10 is a cross-sectional view of the steam
cooker which was disclosed in perspective view in FIG. 9;
FIG. 11 is a cross-sectional view of the bottom
portion of one embodiment of a steam cooker in the
present invention;
FIG. 1,Z is yet another embodiment of a steam
cooker of the present invention;
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FIG: 13 is a cross-sectional view of the steam
cooker disclosed in FIG. 12;
FIG. 14 is a perspective view of the rotary dryer
of the present invention;
FIG. 15 is a cross-sectional view of the rotary
dryer;
FIG. 15A is a cross-sectional view of the
vibratory drainer which is mounted at the opening of the
rotary dryer (as seen in FIG. 14j in the preferred
1o embodiment of this invention;
FIG. 15B is an end view of the vibratory drainer
shown in FIG. 15A;
FIG. 16 is a detailed view of the barrel assembly
housed within the rotary dryer of t:he present invention;
FIG. 16A is a cross-sectional view of the rotary
dryer of the present invention;
FIG. 168 is an end view of the barrel assembly,
showing one arrangement of the containment mechanism that
may be used in the invention;
FIG. 17 is a schematic view of the flow of food
granules and water through the processing steps of the
present invention, including the flow of recirculated
water.
Descrit~tion of the Preferred Embodiment
The Overall ~aratus and Method
In the preferred embodiment of the present
invention, food granules are treated by prewashing,
presteaming, steeping, and then transferring the food
granules to a steam cooker, followed by transfer to one
or more drying stages. After drying, the food granules
may be packaged for distribution t~~ the consumer.
Further, the present invention advantageously utilizes
water in an economical manner by limiting the total
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amount of water used in the processing of the food
granules, and by limiting the amount of water excreted
the processing of the food granules.
The amount of water used in the present invent.. ~
of processing rice, for example, is usually the minim.
amount of water needed to transmit required moisture :~=;d
heat to each of the individual rice grains, and to
prevent the formation of the excess free starch point,
i.e., the "glue" point at which too much free starch is
released, thereby causing the rice to accumulate, and to
no longer move through the processing steps. This is
accomplished by adding water in quantities which are
roughly equivalent to the amount that the rice can absorb
at each particular point in the process. Therefore,
increases in pressure and temperature will allow for
smaller amounts of water to be used in processing the
cereal grains, while achieving a desired level of
gelatinization of the cereal grains without release of
excess free starch.
The overall processing system can be seen in FIG.
1. In FIG. 2, a flow diagram depicts an overview of the
typical flow of food granules through the processing
steps of the present invention. All these steps will be
explained in greater detail below, flow diagram is
provided as an overview to the process. Food granules 58
are first subjected to a prewash step 59 in apparatus 1.2
illustrated in FIG. 1. After prewashing, food granules
are provided to a presteaming step 60 (shown by reference
numeral 20 in FIG. 1), where they are presteamed in
preparaEion for steeping and water absorption step 61
which occurs within moving tanks or buckets 27 (as seen
in FIG. 1). Of course, the buckets 27 seen in FIG. 1 are
merely schematic, and actual implementation of the
conveyor containers may adopt a different appearance from
that shown in FIG. 1, while still performing the same
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~' function. After steeping, the food granules proceed into
steam cooker 90, where they are cooked, and are then
r
provided along conveyor line 38 from the steam cooker to
,' one or more optional stations. As one option, a
microwave or radiowave heater 44 may be provided in-line,
and a gas injection 42 may be provided to the food
granules. Further, an optional pneumatic conveyor heater
40 may apply heat to the food granules.
Upon exiting the cooker and proceeding through
conveyor line 38, the food product is preferably
entrained in a water slurry, which proceeds into
vibratory drainer 300 where water is drained from the
slurry: The food granules then enter the rotary dryer 32,
where the food granules are dried in various temperature
zones. Further, in an optional step 'the food granules may
be provided to a bed dryer 14, or a vertical dryer 15, or
both, and the final product 54 (see :PIG. 2) is dried and
ready for packaging.
Referring back to FIG. 1, food processing system
includes prewasher 12 which receives the uncooked food
granules, and performs a prewashing step. Input 22
provides water to the prewasher 12 which is preferably
ambient temperature at a temperature of approximately
25'C. If desired, the prewasher may be supplied with hot
or cold water input, not shown in FIG. 1. A hot water
input might be used in cases where it is desired to
optimize free starch or surface starch removal.
Prewashing may occur using any of the standard methods of
prewashing rice known in the art. The preferred method is
the so-called "tiff-Rice system, disclosed in Patent
Bulletin No: -5i-22063 and in Japanese Patent ~o, __.__._____ _
__....
57/141257.
In general, a Jiff-Rice unit prewashes rice by
using a rotating centrifugal water application and
separation method. Basically, the rice is washed in
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water, and the water is thrown off of the rice by
centrifugal force in the turning of a centrifugal drum
within the prewasher. In the prewasher 12, rice typically
is washed for about 10 to 60 seconds. If the Jiff-rice
5 process is not being employed, 10 seconds is the
preferred time. If the Jiff-Rice system is employed, then
the washing time may be as much as 60 seconds or perhaps
even more. This prewashing is known in the art pursuant
to the above-described patents, and perhaps other
patents.
The prewashing serves to provide some moisture to
the rice, without giving it too much moisture in the
early stages of the process. If rice or other uncooked
E food granules are given too much water early in the
process, undesirable gluing effects will be observed,
slowing the transport of the food granules through the
cooking apparatus.
After the relatively brief pr ewashing step, food
granul-es are deposited upon conveyor 16 for transport
into the presteamer unit 20, which is supplied with steam
from steam line 49. The presteamer is preferably a bed _
conveyor-type steam unit, of the type known in the art
which sprays steam onto the bed of food granules as they
pass through the steamer from above the conveyor down
onto the conveyor, and also from below the conveyor onto
th~~ foOd granules. The presteaming step is important to
the overall invention because the food product is exposed
to a relatively brief amount of heat and moisture, in
order to avoid damaging or mobilizing surface starch in
the early stages of cooking of the food granule. In_ the" __ ... -
preferred method, each individual granule of rice will be
subjected to the presteamer operation for approximately 5
to 30 minutes. Of course, this may be modified as
desired, and presteaming time will depend upon the
variety of the product being produced.
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The presteaming step assists food granules, and in
particular, assists cereal grains such as rice in
absorbing a relatively small, but appropriate, amount of
water at this point in the process. This step,
therefore, prepares the rice granules to be in a
condition for absorbing further quantities of water in
appropriate amounts in subsequent steps. In the process
of the present invention, one of the most important
factors is that the cereal grains are presteamed before
l0 they are steeped in the buckets 27 in route to the steam
cooker. This process facilitates a controlled moisture
input into the food granules or cereal grains that
increases the ability of the food particle to be cooked
without showing undesirable giuing~ effects. In
particular, the water which is transported along with the
cereal grains during cooking is less likely to contain
large amounts of loose starch which has been extruded
from the cereal grains where a presteaming and a short
steeping step are provided, as in the present invention,
before steam cooking the rice.
After the food granules pass through the
presteamer unit 20, they are deposited into buckets~27
which are intermittently advanced upon conveyor line 50.
The prepared conveyor/bucket system is of a commercially
available design from Nippanki Industrial Co., Ltd. of
Japan. Preferably, approximately 50 pounds of food
granules are deposited into each bucket along conveyor
line 50. Sensing mechanisms (not shown) detect when the
bucket receives a full load of food granules, and at that
point the conveyor system advances one station to a paint
at_which the dispenser. line mixture-34 dispenses water-
into the bucket 27, for a steeping step.
The dispenser line mixture 34 may be comprised of
fresh hot water Which comes from hot water line 18, or
may be comprised of recirculated water from recirculated
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water line 30. Depending upon the type of food granules
processed, and the processing conditions required, it may
be possible to provide recirculated, or recycle water,
from recirculated water line 30, which has already been
processed, back into buckets Z7 for reabsorption by food
granules, thereby minimizing the amount of water used in
the overall processing system, and reducing the amount of
waste water in the overall processing of the food
granules.
The amount of water introduced into each bucket 27
is typically the amount of water needed to provide a
ratio of about 1:1 between the amount of food granules
introduced into the bucket, and the amount of water
introduced into the bucket, on a weight basis. In
particular, the amount of water introduced is regulated
such that it may be completely absorbed, or nearly
completely absorbed, by the food granules before they are
deposited into the steam cooker 90. T'he steeping water
provided into buckets 27 is preferabhy about 80'~C,
although the water temperature will vary for different
processing conditions and different food granules.
Further, in the processing of rice, different varieties
of rice may require a different water temperature for
steeping. Each 50 pound charge of food granules which is
deposited into bucket 27, and then supplied with water,
then proceeds iw:, s epwi~ae fashion towards the steam
cooker 90. Preferably the rice will remain in its
associated bucket and hot water for approximately 5-30
minutes (depending upon processing conditions and variety
30 of food product). The preferred time for milled white
rice is about 10 minutes for appropriate steeping and-
absorption of the water into the rice granules. Upon
reaching the steam cooker, the contents in each bucket
are emptied into the steam cooker, and each bucket is
returned back to the deposit station along the
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undercarriage of the conveyor line 50. A bucket cleaning
station may be included if needed:-'
After proceeding through the steam cooker 90,
which will. be described in more detail in the description
that follows, the cooked ric~ and'water slurry emerges
along conveyor lire 38°, where it advances to a vibratory
drainer:,~00, and then to a rotary dryer 32However, one
or more optional taps. may occur between the staaia
cooker and the rotary.dryer, including the application of
microwaves, radiowaves, or other. electromagnetic
radiation-td tha,food granules at microwave heater 44.
As ;another option,- the food granules may be° subjected to
a gaseous substance, such as carbon dioxide 'at gas
injection station.~2. As- another ~ption, depending upon
the type o! food . granules processed°,- a= pneumatic conveyor
heater.4A~ may be provided to flash off' excess water prior
to entry of the food granules into the rotary dryer 32.
Further, chemical treatments of the rice may be
desirable in some cases: The food granules may be
conditioned by the addition of~- lecithin, rice oil, sugar,
phosphoric acid, adipic acid or other acids. In the
processing of rice, for examples such~che~ical additives
are useful in improving the quality of the'final product.
It should be noted"that the gas injection and the
microwave heating may serve several functions, including
drying the-sur~ace~of the food particles to facilitate
the entry of water into the particle, thereby softening
the food granule. In the case of rice, for example,
microwave heating of the grain produces small fissures in
the exterior'of the grain, allowing for moisture
entrapment within the grain during cooking,- providing a
- highly desirable rice product: carbon dioxide gas may be
provided to cereal grains in order to improve the texture
and to aid gelatinization of the starch within the grain
for a more consistent cereal grails product that is more
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evenly cooked and more desirable to consumers. Due to the
nature of the functions provided by these steps, they
might be performed, either individually or in
combination, or at other additional or different points 5
in the overall process.
Upon arriving at rotary dryer 32, the food product
is exposed to hot air in a manner to be described in
greater detail below. An alternate type dryer might also
utilize sonic energy to aid drying. The food granules
proceed through the rotary dryer, and optionally may
proceed into a bed dryer 14. Whether or not a bed dryer
is required will depend upon the typ~a of food granule
processed, and the degree of drying desired. After drying
in the bed dryer, food granules may optionally proceed to
a vertical dryer 15. Vertical dryer 15 is adapted for
reducing the moisture content of food granules to a
greatly reduced level. Both the bed dryer and vertical
dryer are of conventional design.
Various aspects of the overall process will now be
examined in greater detail.
The Preferred Embodiment
of the Steam Cooker
Steam cooker 90, the preferred embodiment for
steam cooking in the present invention, is shown in FIG.
25 2A. The food granules, which have absorbed water just
prior to entry into the sham s:..ooker, proceed along
conveyor line 50 as seen at the top of FIG. 2A. The food
granules, with absorbed water, are deposited from bucket
27 into the top portion of the steam cooker 90. Further,
hot water line 18 provides hot water to hot water line 99
to the lower section of the steam cooker 90, and this
water may be used to flush the food granule slurry out of
the steam cooker, and to provide an aqueous medium of
transport of the slurry to the rotary dryer. (See FIGS.
3'S) .
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Flow direction arrow 95 shows the direction of
flow of the uncooked food granule.. into the steam cooker.
A hot water line 18 provides hot water for cleaning jet
nozzles 91 which are located in the top portion of the
steam cooker 90. The food granules are deposited onto
drain screen 93, where they are vibrated, and moisture is
allowed to drain from the food granules prior to their
passage through steam chamber aperture 312 seen at the
top and eenter portion of FIG. 2A. The circular
retention bowl 92 receives the food granules, and directs
them downward into the steam chamber aperture 312 with
the vibrational action of the drain screen 93.
The food granules proceed through steam chamber
aperture 312 into the lower portion of the steamer as
seen in FIG. 2A. A plurality of steam lines, for example
steam line 318 and 310, are seen entering the steamer
wall 306, where they provide steam to the food granules
on the interior of the steamer 90. Rotating shutters 308
are seen in cut-away view and in phantom lines at the
middle and lower portion of FIG. 2A. The rotating
shutters 308 are rectangular in shape, and extend between
the side walls of the steamer, and contain steam ports
320 upon their upper surface. Food granules proceed
through the various stages, or layers, of rotating
shutters in stepwise fashion, where they eventually are
released into hopper 314, seen at the lower portion of
FIG. 2A. The hopper is typically a water filled bath
which cools the food granules, and provides a slurry
medium in which food granules proceed prior to
advancement through exit chute 316 out of the steam
cooker 90. Water lines, gas lines or vacuum lines may be
provided in the region of the exit chute 316 to
. facilitate the discharge of food products from the
cooker. Such equipment is more fully discussed in
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connection with the embodiment of FIGS. 3-5, but could
preferably be employed in this embodiment as well.
FIG. 2B shows a cross-section of the lower portion
of the steam cooker previously described in FIG. 2A. ~t
the top of FIG. 2E, the steamer wall 306 is seen on
either side of the figure, with four vertically spaced
layers, or rows, of rotating shutters 308 extending
laterally between steamer walls 306. FIG. 28 shows the
preferred embodiment of the invention, that is, a series
of rotating shutters 308 to advance the food granules
from one stage to the next in sequence. Further, it may
be seen that the lower portion of the cooking apparatus
seen in FIG. 28 is somewhat wider than the upper portion,
allowing for greater throughput of the food granules,
with maximum cooking effectiveness and minimum adverse
"gluing" effects, and also to allow for swelling of the
food product, such as rice, due to the absorption of
water. Perforated steam lines 324 are seen in cross-
section in FIG. 2~, where they proceed laterally beneath
rotating shutters 308. The perforated steam lines serve
two functions. First, they provide steam for the cooking
of the food granules. Second, they provides axes or
hinges of rotation for the rotating shutters 308.
Shutter gap space 338 is the operating gap between
rotating shutters 308, and it facilitates free rotation
of the shutters, while still retaining food granules
within each layer of the steam cooker. FIG. 2C, which is
discussed in more detail below, shows the rotated
position of the shutter 30g seen in phantom lines in FIG.
2C. Each of the shutters seen in FIG. 28 functions by
rotating as shown in FIG. 2C.
Perforated steam lines 322 and 324 in FIG. 2E
provide steam to cook food granules. Further, steam bet
326 extends downwardly and somewhat laterally from the
perforated steam lines, and steam ports 320 are evident
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on the top side or upper side of each rotating shutter
' 308, to provide steam upward into the food granules. In
this way, each charge of food granules is steamed from
above and below as it proceeds in stepwise fashion 5
through the steam cooker.
FIG. 2C shows a closeup view of one rotating
shutter 308 and its associated perforated steam line 322.
In particular, it may be seen that steam ports 320 exist
upon the upper side of the rotating shutter 308, and
steam is allowed to exit these ports. Steam conduit 334
carries steam through the center of the perforated steam
line 322. Outer steam line wall 336 serves as a pivot
point, or hinge, upon which the rotating shutter 308 may
turn on its axis approximately 90'. The rotated position
of the shutter 309 is seen in the phantom lines extending
from the top to the bottom of FIG. 2C;. Steam conduit 334
carries the steam from the exterior of the steam cooker
to the steam jet nozzle 332 and the steam ports 320.
Steam jet 326 is seen as it exits from the steam jet
nozzle 332. The axis of rotation of rotating shutter 308
is shown by arrows at axis 328 and axis 330.
In the operation of the steamer seen at FIGS. 2A-
2C, rice falls through aperture 312 and comes to rest on
top of the uppermost row of closed shutters 308. While in
this position, steam is provided to t:he rice for an
appropriate duration of time from steam pr,:rt:~ '~20 a.nd
steam jet nozzle 332. The shutters will then be rotated
to cause the rice to fall and be col7:ected on the
immediately adjacent vertically spaced row of closed
shutters, where the rice will be subjected to further
steam and cooking. The rice will then proceed through the
cooker onto each immediately adjacent row of shutters for
being subjected to further steam, until the rice has
achieved the appropriate degree of cookinq and moisture
absorption.
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The preferred operation is t~ rotate the rotating
shutters by external activation approximately once per
minute to minute and a half is the case of white rice.
Other types of rice would use other processing
conditions, and might require a longer or shorter period
of time between actuation of the rotating shutters. Once
actuated, the rotating shutters would rotate from a few
degrees to as much as 90°, as necessary to facilitate the
movement of the food granules from one stage (zone) down
to the next zone. In actual practice,'the steamer
preferably would have approximately'10 zones, upon which
food granules would proceed in stegwise fashion through
rotating shutters. .For illustrative purposes only
approximately four or five zones are shown in FIGS. 2A-
2C.Different types of food granules and-thfferent
varieties of rice might require a different number of
zones, and as few as two or three zones, or less', might
be required for certain applications, while as many as 30
zones might be desirable in other apgl cations.~
The actuating method for the rc~thting shutters may
be accomplished by using'a motor,'hydraulic equipment, or
perhaps pneumatic air equipmhnt~ Thevtotal residence
time of rice in the steamer is approximately S to 30
minutes, in the case of long grain white"rice . It is
less or more for other varieties of rice, and for other
varieties of food granules. The residence time for' short
grain rice (i..e:, faster hydrating ricas) is likely to be
less, while. the residence tfme for slower hydrating
ricer, such as parboiled and brown, and wild rice is
likely to be greater. In the'case of lhng grain white
rice, the weight of rice to be held by mach rotating
shutter in each stage (preferably is approximately 2.8
kilograms. Further; the thickness of the'rice layer, in
the case of long grain white rice, would preferably be
approximately five centimeters. In order to secure the
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dropping of rice by turning the rotating shutters, the
thickness of the rice upon the top of each rotating
shutter would preferably be smaller 'than the rotating
radius of the rotating shutter 308, to facilitate the
movement of rice from one zone down 'to the next zone. In
some applications, it may be desirable to feed rice or
food granules out of the steam cooker and directly into a
rotary dryer. However, in the preferred embodiment, and
as seen in FIG. 1, it is believed that pumping the rice
from the steam cooker in the form of a slurry, into a
vibratory drainer 300, and then into the rotary dryer is
the most efficient method for the processing of rice.
The processing of food granules, and different varieties
of rice, may occur by different methods.
In the preferred operation, the pressure within
the cooker will be kept below 15 psi in order to avoid
high pressure regulations which are imposed upon such
high pressure vessels. As the rice exits the cooker, its
water content will be approximately 50%-65% water. These
general conditions will apply not only to this preferred
embodiment, but else the other embodiments of cookers as
well.
Alternative ~abodiments of the Steam
c'~ooker Using a Central Rotating Mechanism
FIG. 3 shows an alternate embodiment for the steam
cooker of the present invention. In FIG. 3, steam cooker
87 is shown, and the food granules, which have absorbed
water just prior to entry into the steam cooker, proceed
along-conveyor line 50 as seen at-the-top of-FIG~ 3-.- In
this alternate embodiment, the food granules, with
absorbed Water, are dumped from bucket 27 into the top
portion of the steam cooker 87. Flow direction arrow 95
again shows the direction of flow of the uncooked food
granules into the steam cooker. A hot Water line 18
provides hot water for cleaning jet nozzles 91 which are
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located in the top portion of the steam cooker 87, and
also provides hot water to hot water line 99. The food
granules are deposited onto drain screen 93, where they
are vibrated, and moisture is allowed to drain from the
food granules prior to their passage through food granule
inlet 94, which is seen at the top and center portion of
FIG. 3. The large circular retention bowl 92 receives
the food granule:, and it directs them downward into the
food granule inlet 94 with the vibrational action of the
drain screen 93.
Different processing conditions and different
types of food granules will determine what type of steam
cooker is most desirable for each application. For
example, the preferred embodiment of the present
invention is the steam cooker shown in FIGS. 2A-2C, and
it is preferred for long grain white rice. Nevertheless,
short grain rice or other varieties of rice, such as
parboiled rice, may be more advantageously cooked using
the rotating mechanism of the steam cooker shown in FIGS.
3-5, or perhaps in the alternate embodiments seen in
FIGS. 6-12. Each of the steam cookers shown in this
specification is contemplated as part of this invention,
and different varieties of food granules will preferably
use different variations of the steam cooker.
Food granules are deposited into the housing 89
which contains the propeller assembly 97 (the cylindrical
dotted portion seen at the center of FIG. 3). The
propeller assembly 9? comprises several parts, which will
be seen in the exploded and detailed view of FIG. 4.
Steam lines 49 provide steam to the exterior wall
of housing 89 as seen in FIG. 3. Further, rotary blades
98 are seen in phantom lines at the center of FIG. 3, as
part of the propeller assembly 97. Hot water line 99
provides hot water to the hopper 80, which may be used to
flush the food granule slurry from the hopper, and to
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a
provide a water transport means to ths: rotary dryer.
Recirculated water line 30 also extends into the housing
89.
At the Iower portion of FIG. 3, steam line 49 is
seen entering the housing, and hot water line 99 provides
hot water to the lower portion of the steam cooker
comprising the hopper 80. At the lower. portion of FIG. 3,
in phantom, can be seen the rotating crank shaft 103. The
rotating crank shaft 103 is connected to the propeller
assembly 97, and it rotates, causing the rotation of the
rotary blades 98.
During operation of the steam cooker, the rotary
blades 98 act to propel the food gramules from the top of
the cooker down to the bottom of the cooker. The blades
also support the food granules, and provide a uniform
mixture of food granules while the granules are being
steamed in the steam cooker. Further, the rotating action
provided by rotating crank shaft 103 assists in
preventing the gluing and sticking together of the food
2o granules, which may otherwise occur.
Support frame 112 supports the steam cooker, and
power is provided to the rotating crank shaft 103 by way
of motor 102, which is connected to a. belt 100 wrapped
around a pulley 101.
In FIG. 4, an exploded and detailed view of
~Eahepropeller assembly 97 is provided. The central axis
109 of the propeller assembly is seen as dotted lines.
FIG. 4 also shows a rotating scraper cap 105 upon which
is mounted an optional scraper connecting unit 107, only
part of which is shown in FIG. 3. The: scraper connecting
unit 107 is connected to two separate scraper arms 106,
which in turn are connected to scrapers 104. The rotating
scraper cap 105 is fixedly connected to the rotating
crank shaft 103 which extends up through the35 entire
assembly as shown in FIG. 4. The scrapers rotate
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to effect a uniform distribution of the food granules as
' they enter the interior of the steam cooker 90.
At the center and left portion of FIG. 4, the
housing 89 is seen in cut-away view whereby the
stationary blades 108 may be seen on the interior wall of
the housing 89. Twelve stationary blades are shown on the
cut-away section, which comprises approximately onehalf
of the entire housing 89. Steam chamber 110 may be seen
on the exterior periphery, and it is within the steam
chamber 110 that steam is injected by way of steam lines
49 and then distributed inward through porous wall 123.
Porous wall 123 may be formed, for example, by a
cylindrically shaped portion of steel or aluminum mesh.
Further, in FIG. 4, the rotating cylinder 111,
which is connected to the rotating crank shaft 103 is
seen at the top right portion of FIG. 4. It rotates
within the housing 89, and comprises a plurality of
rotary blades 98 which are arranged an three distinct
zones along the longitudinal length of the rotating
cylinder 111. The rotary blades 98 assist in advancing
the food granules through the cooking apparatus, and also
provide a platform upon which the food granule slurry may
rest, to prevent the pressure of the slurry from becoming
so great that large globules are formed within the
chamber. Thus, rotary blades 98 and stationary blades 108
h~:~.~; '~.o keep tha food granule slurry both supported and
mixed, to prevent globular portions from forming within
the steam cooker 90.
The rotating cylinder 111 is m~unted upon the
rotating crank shaft 103 which extends along the central
axis 109 up through the rotating cylinder 111 where it
engages the rotating scraper cap 105.
Mist 114 extends up through the interior of the
rotating crank shaft 103 to provide a mixture of steam
and water mist to the food granule
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slurry. Further, steam line 49 is provided with a
plurality of steam nozzles 113 which are located along
the interior of rotating cylinder 111, and provide jets
of steam from the interior through the wall of the
rotating cylinder-111 and out into the chamber where the
food granules are contained. Like e~cterior wall 123,
rotating cylinder iii is porous to permit the passage of
steam. Thus,:the food granules-receive steam from two
directions,':from steam chamber 110~from the outside, and
-from the inside by way of steam nozzles 113,- in'order to
achi~ve more uniforia cooking and water absorption:
At .tee lower right portion of rFIG. 4;' one can see
housing 89 which is shown-in a-cut-away view, and hot
water line 99 extends out fr~~n the housing. Recirculated
water line 30 drains exeess water=from the interior of
the steam chamber and, as seen in FIG: 1, provides
recirculated water for reabsorptio~n:;~along dispenser line
mixture 34 back into'-buckets 27: Iri this way, less"water
is utilized in cooking, and more w~at~ar is retained within
the processing system.
Spoke 115 provides a structural member supporting
the steam cooker, and a hopper 80 essentially comprises a
water bath near the lower portion of the~~ team cooker
upon. which the rice falls after-it is cooked: Steam line
49 enters the steam chamber through the~wall of hopper
80. Iiot~. water line 99 also provides hot water, if
needed, to the hopper 80. In soma cases, a hot water
flush may. be desirable- to flush-globules--of-food-granules-
out of the hopper 80, and unto conveyor line 38 for
transfer to the rotary dryer 32~ Power is provided to'
the rotating crank shaft 10 by way of motor 102, which~is
conn~cted to belt 100, wrragped around pulley 101:
F'IG: 5 depicts a cross-section of the steam cooker
shown in FIGS. 3 and 4. At the top of FiG:5, uncooked
food granules 62 are dumped into the retention bowl 92,
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where they are vibrated upon drain screen 93. Hot water
line 18 is seen at the top of the retention bowl 92,
where it provides a plurality of cleaning jet nozzles 91
that may be used to clean the screen or to provide a hot
water spray upon the food granules if desired.
Vibration of the drain screen 93 is provided by
vibratory motor 117, which provides vibrating action for
the entire drain screen. Water is drained into drain
.space 118 around the periphery of the food granule inlet
94, and the water is collected and drained away through
streamer drain line 37. As seen in FIG. 1, the contents
of steamer drain line 37 is later filtered, and some
portion of that water may be reused and reabsorbed along
the dispenser line mixture 34 into bucket 27 Csee Fig. 15
1). Also, some portion of this recirculated water may be
drained at drain 29 as seen in FIG. 1.
FIG. 5 illustrates the manner in which the food
granules proceed through the food granule inlet 94 as
indicated by the arrow at the top. The granules are
dispersed, and fall upon the rotary scraper cap 105,
wherein scrapers 104 rotate in distributing the food
granules, and helping to feed them into the steam cooker.
Scraper connecting unit 107 is seen as it forms its
connection between rotating scraper cap 105 and scrapers
i04.
The food ~~~°.ara~? d e.s t~~,en proceed into the steam
cooker in a continuous batch, and they are mixed and
distributed with the assistance of stationary blades 108,
which do not move, and rotary blades 98, which are
rotated in three discrete zones as seen in FiG. 5, around
the periphery of the rotating cylinder 111. The rotary
blades contain on their underside a steam line 122, from
which steam nozzles 124 provide steam to the food
granules within the chamber. These steam lines 122 line
114.
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Rotating crank shaft 103 rotates the rotating
blades 98 at a relatively low rate of speed, in the range
of 1 rpm to 10 rpm and preferably about 5 rpm. Care
should be taken not to agitate the granules to any
significant degree, so as to avoid breakage of the
individual kernels. As a result, the :rice proceeds
through the cooking chamber, being steamed from the
exterior by a plurality of steam jets around the
circumference of the cooker, which are contained within
10 steam chamber 110. Steam lines 49 are seen as they
enter from the exterior of the steam cooker into the
interior space of steam chamber 110.
Hot water line 99 is seen on the right side of
FIG. 5, and level sensor 116 is slightly below hot water
line 99. Below that can be seen recirculated water line
30, which may drain off excess water from the hopper 80
and provide it to be recirculated and perhaps reabsorbed
in buckets 27 as seen in FIG. 1. Sensor 125 is seen below
recirculated water line 30, and it operates to sense the
temperature of the water to prevent the water temperature
from becoming too great. This sensor may assist in
minimizing starch damage and gluing effects.
As shown in FIG. 5, hopper 80 is seen as the
portion of the steam cooker wherein the rice falls after
it is thoroughly mixed and cooked. Scream line 49 is seen
at the lower left portion of F:~'~'.. 5,, and dot water line
99 is provided in the region of the hopper 80 to
facilitate a hot water flush, if desired.
Motor 102 provides power generated by way of belt
100, which drives pulley 101, thus turning the rotating
crank shaft 103. Steam line 49 and hot water line 18 are
seen at the very bottom of FIG. 5, where they enter the
region of the crank shaft 103 and proceed upward as seen
in the dotted phantom lines along the interior of the
crank shaft 103. Mist line 114, which
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' g provides a steam and water mist to the food granules
within the chamber, may be adjusted to provide the
desired mixture of water and steam which is necessary for
cooking the particular variety of food granule. Some food
granules may require more water and less steam, while
others require more steam and less water to fully cook
the granules prior to exit from the steam chamber.
In the preferred operation, rice will remain
within the cooker 90 for approximately 10 to 15 minutes,
approximately the same amount of residence time as in the
steeping operation. Thus, the steeping and cooking
operations may be coordinated. While the rice is in the
cooker, it will continue to absorb water in an optimal
manner, i.e., in an amount roughly equivalent to the
amount of water that can be absorbed by the granules at
that paint in the process, and the starches are
gelatinized. The temperature and pressure within the
cooker will be coordinated to achieve optimal results for
cooking the rice while avoiding undesirable "gluing" or
sticking.
Further Alternate Embodiments
of the Steam Cooker
In general, it should be noted that numerous
embodiments of steam cookers may be used in the present
invention. Different arrangements of the cooker wall be
preferred for different types of food granui.~s, and
different varieties of cereal grains or different
varieties of rice may require variations in the design of
the steam cooker to maximize cooking effectiveness.
FIGS. 6-8 illustrate an alternate embodiment of
the present invention; which also may provide -
advantageous results for steaming certain types of food
granules such as certain varieties of rice. Bucket 27 is
seen at the tog of FIG. 6 where it proceeds along
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conveyor line 50, dumping a load o:~ uncooked food
granules 62 into the top portion of the steam Booker.
The granules are deposited into a funnel segment
64 at the upper end of the steam cooker. The uncooked
food granules 62 preferably will free-fall upon cone
spreader 78 where the food granules are distributed in an
even fashion around the periphery ~of cone spreader 78.
Further, funnel segment 64 may be selectively rotated to
assist in the even distribution of food granules around
its periphery, thus assisting in the uniform and complete
cooking of food granules. The rotation could be
clockwise or counter-clockwise, and in the preferred
embodiment, the rotation of the funnel segment 64 would
be in the same direction (i.e., clockwise or counter-
clockwise) as the rotation of the discharge segment 68.
In the steam cooker 46, cylindrical housing 74 is
comprised of a plurality of segments, including funnel
segment 64, middle segment 66, and discharge segment 68.
Pipe entry segment 148 is located between the middle
segment 66 and the discharge segment 68 in the preferred
embodiment as seen in FIG. 6. Through~segment 148, hot
water line 18 and steam line 49 enter the cylindrical
housing 74, as seen in FIG. 6. The food granules proceed
through the segments, and they are picked up by the
rotating discharge segment 68 as it turns on its central
axis. The food granules proceed into hopper 80, and then
fall into venturi segment 84.
The flow rate of food grarniles through the steam
cooker may be inhibited, especially near the discharge
end of the steam cooker at hopper 80: To encourage free
flow of food granules through the hopper, and especially
in the case of cereal grains or rice products, which may
exhibit a gluing effect which prohibits advancement of
the rice grains through the steam cooker, the venturi
segment 84 may be provided with an air or gas feed line
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82 (which could alternatively provide a vacuum] that
provides air or gas pressure (or a vacuum) to assist in
the advancement of the food granules from the butterfly
valve 86 to exit the steam cooker through butterfly valve
88.
The rotation of various segments of the
cylindrical housing in the alternate embodiment, as seen
in FIGS. 6 and 7, provides for greater uniformity of
cooking and distribution of food granule flow through the
steam cooker. In the case of cereal grains, once the
cereal grains pass into the steam cooker, the goal is to
cook the grains at the lowest possible moisture content
to reduce the amount of time required in the steam
cooker. A reduction in the moisture level and the time
required for cooking is advantageous, but the reduction
in moisture level must not be so great as to cause
undesirable gluing effects within the cavity of the steam
chamber. This principle applies not only to this
embodiment, but to all in this disclosure.
Typically, only a small amount of pressure is
achieved within the steam chamber of FIGS. 6-12, as in
the preferred embodiment shown in FIGS. 2A-2C, and the
alternate embodiment seen in FIGS. 3-5; the pressure is
preferably maintained below 15 psi to avoid the necessity
for complying with governmental regulations and local
codes for pressurized vessels. This, of course, is only
preferable and may be modified as desired or needed. The
pressure is maintained by the downward force of the rice
within the vessel and by the introduction of steam under
pressure into cooking chambers.
A small opening 75 at the top of conical section
78, as seen in FIG. 6, permits steam to escape from
within the cooking vessel, but the opening is sized to
restrict the escape of steam in order to achieve the
desired interior pressure.
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The vessel is typically operated at a pressure of
approximately 5 psi, but htis may be warried as desired.
A greater pressure within the steam chamber will increase
the temperature of the chamber, without a corresponding
addition of moisture. Thus, the primary variables in the
cooking of food granules are the pressure, the
temperature, and the moisture content of the food granule
slurry.
In the embodiment shown in FIG. 6, there is
synchronized rotation between the discharge segment 68
and the funnel segment 64. Hot water is provided through
hot water line 18 at a temperature of between 90°C and
100°C. It is preferred that the cooker be arranged
vertically, so that the flow of food granules through the
cooker is assisted by gravity. The average time a
particular food granule resides in the steam cooker
itself is preferably about 10 to 15 minutes, although
cooking times will vary widely for different types of
food granules. A synchronized rotation between segments
64 and 68 of about 5 revolutions per minute is the
maximum typically used; the minimum rpm of the rotating
segments is 0.2 rpm.
In FIG. 7, an exploded view of the cooker of FIG.
' 6 is shown. Steam jet 76 emerges from the top of cone
spreader 78 in the funnel segment 64. Funnel segment 64
rotates, preferably in synchronous rotation with
discharge segment 68. Along the central axis of the
steam cooker is central hot water line 138 and central
steam line 140. These lines provide hot water and steam
to the cooking chambers 142 which are arranged around the
periphery of middle segment 66.
The cooking chambers are preferably separated by
partitions 143, although it is not required that the
chambers be separated in such a way" Pipe entry segment
148 is located between middle segment 66 and discharge
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WO 95106416 ~ ~ PCTNS9~ .98
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segment 68, and it provides for entry of the hot water
line 18 and steam line 49 from t:he exterior of the steam
cooker into the plenum chamber 144, which is the chamber
running along the center of the steam cooker from which
steam and hot water emanates into the cooking chambers
radially outwardly. Discharge siegment 68 is provided
with a spreader window 154 which, when the discharge
segment 68 is rotated, provides a uniform distribution
and spreads the food granules in an even manner as they
i0 emerge from the various Booking chambers 142.
Spreading of the food granules in this way
provides for more uniform cooking, and a more
advantageous distribution as the food granule slurry
proceeds through the processing of the present invention.
Hopper 80 collects food granules and they are discharged
through venturi segment 84, which comprises butterfly
valve 86 and butterfly valve 88. Air or gas may be
provided along air or gas feed line 82, and a vacuum may
be pulled to provide a venturi effect which may advance
2o food granules out of the steam chamber more efficiently.
In FIG. 8, a pie-shaped section of a cooking
chamber 142 is seen in expanded view, which shows two
partitions 143, the exterior wall 146 and the
perforations 152 on the interior perforated wall 150.
Hot water and/or steam may be provided through
perforations 152 to the food granules residing in cooking
chamber 142. Additionally, openings may be provided in
the exterior wall 146 to receive hot water and/or steam
from a supply plenum tnot shown). In this manner, steam
is provided from two different directions in order to
provide more uniform cooking and to better regulate the
water supply and absorption.
In operation of the embodiment shown in FIG. 7,
rice is conveyed in buckets 27 by way of conveyor 50 to
the funnel segment 64, where it is deposited into the
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funnel segment. Food granules will accumulate in each
chamber and will be subjected to an internal pressure of
5-15 psi. A typical residence time of the food granules
within a chamber will be approximately 10 to l5 minutes,
although this can be varied as desired. Most preferably,
steam will be supplied both from the openings 152 (FIG.
8) and from openings in the exterior wall 146, in order
to achieve as much uniformity in the exposure of each
individual grain as is practical.
As indicated above, food granules will accumulate
in each cooking chamber by virtue of discharge segment
68. As will be appreciated, opening 154 in segment 68
permits only a limited amount of food granules to drop by
gravity from each cooking chamber. Surface 155 provides
a support surface on which the cooked food granules rest,
until opening 154 passes each chamber in turn to permit a
limited quantity of rice to drop.
In FIG. 9, still another alternate embodiment of
the steam cooker is disclosed. Food granules are
provided into input funnel 172 where they fall into entry
chamber 174 and upon the surface of cone spreader 78. In
this embodiment, the steaming chambers are provided in an
alternating arrangement, such that cooking chambers 142
alternate with plenum chambers 144 around the periphery
of a central chamber 184. Steam is provided through
steam line 72 from the exterior of the steam cooker and
it proceeds into the four plenum chambers where it is
provided through wire mesh or perforated walls into the
respective cooking chambers I42.
3.0 Further, an arrangement whereby a spindle 182 is
aligned along the central axis of the steam cooker is
seen in FIG. 9. A discharge paddle 180 rotates discharge
paddle blades 176 to assist in the even spreading of food
granules and discharge of food granules from the bottom
of the steam cooker. In this way, food granules may be
SIIBS'f'INfE SHEf:T (RULE 26~
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evenly distributed and discharged through hopper 80 and
through discharge port 178.
FIG. 10 shows a cross-sectional view of the steam
cooker shown in FIG. 9, whereby the steam enters through
steam line 72 and is provided to cooking chambers 142 by
way of perforated walls which extend generally radially
and define the cooking chamber.
FIG. 11 shows an alternate apparatus and method
which may be utilized to assist in the advancement of
food granules out of the bottom of the cooking chamber.
In FIG. 1l, cooking chamber 142 is shown whereby rotating
distributor 188 rotates about the central axis of the
cooking chamber to allow cooked food granules 190 to be
evenly distributed and in their exit from the cooking
chamber. Rotating axle 194 is seen on the right side of
FIG. 11. Food granules proceed in a downward
progression. Upper frame support 192, lower frame
support 198, and frame support 196 provide the exterior
- surface of the cooking chamber. The housing floor 200
2o provides stability to the bottom of the cooking chamber.
In another embodiment of -he steam cooker of the
present invention, as seen in FIG. 12, steam may be
provided through steam line 206 into rotary valve 204 and
ultimately into central chamber 184 (see cross-sectional
view in FIG. 13). In this arrangement, the cooking
chamber is substantially the same as that of FIG. 9, with
the exception that steam is provided directly from steam
line 72 into the central chamber 184, where it is
distributed into cooking chamber 142 along the central
axis outward from the center...of_ he. chamber. In other
respects, the embodiment shown in FIGS. 12 and 13 is
substantially similar to that shown in FIGS. 9 and 10.
The preferred dimensions of the steam cooker of
the present invention would be with an outer dimension
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(measured across the cooker) of approximately 8 feet,
although other sizes could be utilized.
a D ina Apearatus and Methods
A rotary dryer is'used in the preferred embodiment
of this invention for drying the food granules. In some
cases, for certain types of food granule; a bed dryer
may also be used. In the drying of rice, for example, a
rotary dryer and a bed dryer typically az°e used.
Further, in making a highly dehydrated rice such as a
quick rehydrating variety of rice, a vertical dryer~also
is~used to reduce the moisture content of'the rice to a
low level.
Further, a vibratosy draineirseen in FIG. 1, is
preferably used in cases where~the'food granule slurry is
pumped in a water slurry form from the steam'cooker to
the rotary dryer. FIGS. lSA and 15H shown, respectively,
a cross-section and an end view of the vibratory drainer,
as-shown affixed to the entrance of the rotary dryer in
FIG. 1.
Of course there ara numerous methods of
transporting: the food 'granules front the 'ste$m cooker to
the rotary drying apparatus,' and transport by using a
water slurry is only one method: For example, a dry
transport method could use a combination of rice/air
transport by blowing the-rice through a'conduit, or rice
could be transferred on ~ conveyor belt, if sufficient
apparatus (such a breakers) are employed to prevent
lumping of tha food granules.
The primary purpose of the vibratory drainer as
seen in FIGS: 15A and 15H is to take water out of_ the_
rice early in the drying process, and to reduce the
moisture content of the rice so that the energy
consumption of the dryer will be reduced. Further, the
amount of maintenance required with regard to the drying
~g~TUT'E SHEET (~IlLE 26)
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_ ~..:~ _ 36
' ° apparatus may be reduced by avoiding entry of large of
' water into the dryer. Further, reducing water from the
food granule slurry in the vibratory drainer helps to
create a more uniform feedstock to the dryer.
FIGS. 15A and 15B show the details of the
vibratory drainer 300. The drainer preferably receives
the input food granule slurry 344 as seen in the top of
FIG. 15A. The slurry is deposited onto the vibrating
screen 346, where the food granules proceed down the food
10 slurry channel 348 towards the right side of the
drainer, as seen in FIG. 15A. The food slurry channel is
bounded on its upper surface by the top wall 350. Intake
port 352 is seen as the opening in the upper portion of
the food slurry channel, and water drain space 354
extends 15 along the underside of the vibrating screen
346. Water drains from the food granule slurry into the
water drain space, where it collects an water reservoir
356. Water then proceeds out water exit port 358 into
water return line 302 (shown in Fig. 1). The food
granules which have reduced water content, proceed out
the food 20 granule exit 362, and into the drying
apparatus. A support structure 360 forms the frame upon
which the vibrating drainer is mounted. A vibrating motor
364 is seen on the underside of the water drain space,
and a water level sensor 366 extends into the water
reserydø~.~.:~ to eatable the shut down of the vibratory
drainer if the water level should rise too high, for
example, in a case where the water exit port becomes
clogged. Right upper support strut 36.9 is seen in the
upper left gortion of FIG. 15A, and right lower support
strut 368 is seen on the left side of FIG. 15A.
FIG. 158 shows an end view of the vibratory
drainer 300. In this view, the intake: port 352 is seen at
the top of the figure, with the top wall 350 extending
below that level. The left upper support strut 370 and
the left lower support strut 371 may be seen at the right
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37
edge of FIG. 158. Further, the food granule exit 362 is
seen at the center of FIG. 15B, and the water reservoir
356 and water exit port 358 are .:een at the lower portion
of FIG. 15B. A support structurs~ 360 is seen on either
side of the vibratory drainer and supporting the
structure.
A remarkable drying effect may be achieved
pursuant to the present invention, and in an efficient
manner. ~In FIG. 14, the rotary dryer 32 is provided~with
a cooked slurry of food granules from vibratory drainer
300 (see FIG. 1 and FIGS. 15A and 15B). The food
granules from the vibratory drainer proceed into entry
station 226 (FIG. 14) where any remaining water is
drained from the slurry through drain line 36. This
excess water is recirculated in the recirculation cycle
of the invention.
The food granules are provided to the body of the
rotary dryer where they are dried as they proceed into
the various heat zones of the dryer. The heat zones that
may be seen in FIG. 14 are the first heat zone 268, the
second heat zone 270, the third heat zone 272, and the
fourth heat zone 274. The heat zones may be regulated to
various temperatures for various 'types of drying,
depending upon the food particle to be dried (whether it
is a cereal grain, a parboiled rice, a short grain rice,
etc.) and the temperature of each zone may be regulated
to achieve the maximum drying effect for the minimum
amount of energy consumption of the dryer. Four separate
burners 222 are provided, one to each heat zone, and
blower-fans 56 recirculate heated air fro~u the main
drying chamber through the baffle plate 234 into the
rotating barrel, and then into the recirculation duct 232
and then eventually back into the drying chamber see
FIG. 15). As cooked food granules 238 proceed through
the body of the dryer, (in the direction of the arrows
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seen in FIG. 14) their moisture content is reduced.
Exhaust fan 216 is provided at the upper end of the
rotary dryer to provide a positive air current floe _ong
the path of ~:.~e food particles being dried. Dried Jd
granules 218 emerge from the distal end of the rots I
dryer.
In FIG. 15, a cross-sectional view of the rotary
dryer is seen. Barrel 230 is rotated about central axle
224. Line 16A (FIG. 14) forms the central axis about
which the barrel 230 rotates (see FIG. 15). The food
granules proceed along the inner surface of the barrel
230. Air flows from the inner portion of the barrel in
drying zone 244 out through the damper 236 and into the
recirculation duct 232, where it is circulated back into
blower fan 56, and provided through baffle plate 234 back
into the drying zone 244. Thus, the air is provided in a
circular path about which drying of the food granules may
take place. Burner 222 is seen in FIG. 15 as providing a
heat source for heating the circulating air. A lower
housing 242 and lower damper 240 may be seen in FIG. 15.
Damper 236 and blower 56 and baffle plate 234 each array be
adjusted to provide appropriate air speed through the
rotary barrel.
The air speed at baffle plate 234 is typically
less than the air speed within the rotating barrel 230,
and the air speed is preferably in the range of 20~0 to '
3500 feet per minute within the rotary barrel. The speed
of the air is increased upon entry into the rotating
barrel due to its passage through perforations in the
rotating barrel..
FIG. 16 shows barrel assembly 276 which forms a
major component of the rotary dryer. Beginning at the
left of FIG. 16, motor 220 is seen attached to central
axle 224, and it provides rotational torque to the axle.
Front end housing 374 forms the reservoir into which the
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wet food granules proceed from the entry station 226.
Food granules proceed along the barrel. The barrel is
preferably comprised of wire mesh of sufficiently close
spacing such that the food particles will not pass
through the mesh, but air and water may freely pass
through such mesh. Dryer 32 may be positioned at a
slight downward incline from the entry end to its exit
end to facilitate the movement of rice.
A rear bearing 258 is held by support 264.
Central axle 224 is secured to the motor 220. The motor
220 provides rotational motion to central axle 224. A
housing 264 supports the motor assembly.
The rotary dryer is used for initial drying of the
product and the residence time of a rice grain in the
rotary dryer typically is in the range of approximately 2
to 7 minutes, preferably about 3 minutes. The air volume
used in the rotary dryer may be .as little as 3,000 or as
great as 7,000 cubic feet per minute. The temperature of
the air typically is in the range of between 250°F and
400°F, preferably about 350°F, although it will usually
vary in different zones.
FIGS. 16A and 168 show a closeup and detailed view
of the barrel assembly which forms the inner rotating
portion of the rotary dryer seen in FIG. 14. In FIG.
i6A, food granules which exit the vibratory drainer
proceed into the entry station 226 as seen at the left
side of FIG. 16A. Drain reservoir 412 receives excess
water from the food granules after they are deposited
into the rotary dryer, and excess water passes along to
drain l ne.36 as. seen. in the--lower left-portion of FIG:
16A. They are deposited into the body of the rotary
dryer, where a central axle 224 is turning, causing the
barrel 230 to rotate on the axis of the central axle 224.
Spiral flights 386 and 388 are seen at the left side of
FIG. 16A. Food granules, when they first enter the
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- 40
rotary dryer, are in the form of wet globules which must
be moved along within the rotary dryer by physical means
to flash off the water. This lateral movement from left
to right is provided by the spiral flights 386 and 388,
as seen in FIG. 16A. Meanwhile, blower ports 376, 378,
380, 382, and 384 provide hot air circulation input which
passes through the rotating barrel of the rotary dryer,
and then exits the rotary dryer by way of lower air
intakes-406, 407, 408, and 409.
As the hot air passes over the food granules
within the rotating barrel, water is removed from the
food granules. When the food granules have proceeded
approximately halfway down the rotating barrel, the
granules encounter mixing roller 392, which is fixedly
mounted near the exit point of the rotating barrel, at
the right side of FIG. 16A. The mixing roller 392 also
rotates, which provides a working action of fingers 390,
which are mounted upon the mixing roller 392. The
fingers 390 helg to loosen up and "fluff" the food
granules (particularly in the case of rice), and they
assist in the drying of the rice in the latter stage of
the rotary dryer.
Once the rice or other food granules are
sufficiently dry, they proceed to the fat right end of
the barrel 230, where they encounter adjustable lip plate
400. This plate may be seen at the far right portion of
16A, as a small projection which extends up from the
lower right edge of the rotating barrel. In the case of
rice, the preferred method of determining retention time
- 34 - of- the --r-ice--~.n the dryer --is--to- al-low-- the- rice to remain-
within the rotating barrel until the rice is dry enough,
and therefore light enough in weight, such that the
action of the rotating barrel will make the rice "hop"
over the adjustable lip plate 400. In this way, the
adjustable lig plate acts as a hurdle over which the rice
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will bounce once it has become light-enough, due to the
action of the rotating barrel 230: After the food
granules have passed from the barrel 230, they enter the
collection gone 403. Collection zone 403 is defined by
the end housing 394, which for~as its periphery, and the
food granules proceed down through the food'granule exit
vent 396.
FIG: 5.6H shows an end view of the rotating barrel
as seen-along lines 168 as seen at the right margin of
FIG. 16A. In FIG. 168, an inner bearing 398 may be seen
at the center of the rotating-ba~crel 230v: 'Upon this
bearing, is the rotating'central-axle 22~ which comprises
four spokes 404 extending at right angles'out from the
central axle. Adjustable lip plat~ 400 is seen
releasably mounted upon the end of the barrel 230. This
lip plate provides the "hurdle" over which food granules
may be required-to bounce- in order to exit the rotary
dryer: The iip'plate may be adjusted, by simply removing
it and replacing' it with a lip plate ~of a' different
internal diameter, which would pr~vide a slightly Lower
or higher "hurdle" for the food g=anules to bounce over
upon exit from the barrel: . . _
There are numerous variables in the drying of
rice: Variables include, first, the amount of hydration
of the rice as it enters the rotary dryer. Second,' the
velocity of the air in the rotary'dryer. Third, the
' temperature of the air within the rotary dryer. Fourth,
the rotation speed of the barrel 230. Fifth, the suction
of the air laterally from left to right. Sixth, the
size, shape-; and type of the food granule or rice product
being dried in the rotary dryer. .Seventh, ~e~adjustable
lip plate at the end of the barrel, which may be raised
os lowered to increase or decrease the residence time of
the food granules within the barrel. Each of these
variables may be adjusted for the most efficient drying
SUBSTITUTE SNEE'~ (RULE 26)
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operation pertaining to that particular type of food
granule, and the particular type of processing desired.
Rotational speeds of the barrel of Less than one
cycle per second are preferred. The rotary dryer of the
present invention provides the capability to partially
dry the surface of the wet food granules or grains, which
aids in maximizing the puffing of the final product.
Further, the rotational speed of the barrel is relatively
low, and the rice preferably is not subjected to large
amounts of g forces as in some prior art methods. In this
invention, rice is not "plastered" tea the inner wall of
the rotating barrel in a high speed spin, but instead is
subjected to less than one g of force radially directed
from the shaft towards the wall of the rotating barrel.
For some applications, it may be desirable to
provide variation in the temperature of the heat zones
268, 270, 272, 274 and 275 within the rotary dryer. For
example, in the first heat zone, seen as first heat zone
268 in FIG. 16A, the air throughput may be very high,
' 20 with a relatively high temperature to provide a more
desirable rice product. The temperature variations along
the barrel 230 will provide different degrees of product
uniformity, and different amounts of puffing to create
the type of product desired. _
In the drying of the food granules in the present
invention, a typ~,f~::da~. bid. d~~~yer and vertical dryer may be
used, both of which are known in the art for drying
cereal grains such as rice. In the drying of cereal
grains, such as rice, the object is to "set" the product,
that is, to give the rice grain a good characteristic for
the consumer. It is desirable to "freeze" the rice in a
swelled state, by drying it and providing a swelling
effect of the water within the rice grain during drying.
Further, a puffing effect is desirable whereby
water
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provides pockets of steam within each rice kernel,
expanding the grain of rice, to provide appropriate
texture and desirable qualities f or the consumer.
In a bed drying operation, as indicated by
reference numeral 14 in FIG. 1, t:he temperature is
typically between 275°F and 325°F, preferably about
300°F.
A bed dryer is a belt dryer whereby rice is provided
through the dryer on a bed or be7lt, and air is blown
either down onto the belt or up through the bottom of the
belt. In such bed drying operations, the air velocity is
much lower than the rotary drying operation, typically
about 300 feet per minute. In the bed drying operation,
a residence time of approximately 5 to 15 minutes,
preferably about 10 minutes is used.
For certain types of cereal grains, and in
particular for quickly rehydrating races, a vertical
dryer, as indicated by reference numeral 15 in FIG. 1,
may be used to greatly reduce the moisture content of
rice down to a level as low as 6 % water. For example, a
vertical dryer may be used to provide grain with a
residence time in the dryer of approximately two hours.
- The principles of bed and vertical drying ase known by
persons skilled in the art.
The Efficient Use of
!later in the Presgnt Invention
In the processing of the food granules, water is
recirculated and reused so that the amount of water used
in the processing of food granules is minimized, i.e.,
the_ amount of water used_ and/or ~:xcreted- per pound of
food processed is kept at a low level.
FIG. l7 shows the water pathways in the present
invention and, in particular, shows the recirculation of
water in the present invention in reducing the amount of
water consumed and excreted. As shown in both FIGS. 1
and 17, in the cooking of food granules, heat exchanger
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24 provides heat to and absorbs heat from the various hot
water and steam lines in the processing system. For
example, fresh water inlet 26 provides water into the
heat exchanger 24, and boiler 28 is provided Water from
inlet 52. Steam from the boiler may be provided to the
heat exchanger along steam line 49, and steam line 4?
extends between the heat exchanger and the boiler 28.
The water food granule slurry which proceeds along
conveyor~line 38 into the vibratory drainer 300 is
l0 drained. The drained "used" or recirculated water is
provided along drain line 36 to a point at which it is
mixed with steamer drain line 3?, which comprises "used"
water from the steamer. These two lines are mixed (as
seen in the upper left hand corner of FIG. 1?) into a
combined drain line 39. This combined drain line is
provided to filter 2?8 as.seen in FIG. 1?, and also as
seen in FIG. 1.
The filter essentially provides a macroscopic
filtering of foreign particles from the water, and the
Water is then provided to alternate routes. It may be
provided along exit line 120 where it may be valued to
one of two places. It can proceed along drain line 121,
or it may proceed along recirculated water line 30 to be
fed back into the steam cooker for reabsorption by the
food granules and used in the cooking of food granules at
steam cooker 90. If the recirculated water is fed along
drain line 121, it may be drained out of the system (into
the sewer) from drain 29. As another pathway, the
recirculated water may be sent through valuing along the
path of dispenser line mixture 34, where it may be
reinjected into a bucket 2? for reabsorption by uncooked
food granules as they proceed towards the steam cooker.
Furthermore, the water that drips from buckets 27
upon release of the food granules from the buckets along
the conveyor 50 is collected under the conveyer 50 and
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provided along drain line 41 to steamer drain line 37, in
a similar manner as the water which is drained along
drain line 36. Again, a portion of the "used" water may
be drained away from the system at drain 29, while some
of it is recirculated back into the buckets 27. Further,
hot water line 18 provides hot water from the heat
exchanger 24 to the steam cooker 90.
In FIG. 1, the amount of water provided to bucket
27 through dispenser line mixture 34 will depend upon the
steeping conditions of that particular batch. For
certain food granules, a greater mixture of fresh water
may be required to prevent gluing of food particles
together and to facilitate the free flow of food granules
through the system. For maximum water conservation,
however, the amount of water provided at hot water line
18 is kept to a minimum, while the recirculated water
line 30 is allowed to provide a maximum amount of
recycled water, thereby aiding in the overall
conservation of water.
Further, fresh hot water is provided from the heat
exchanger 24 through hot water line 18 to either the
steam cooker 90 or to the prewasher 12. Hot water line
18 provides hot water along hot water line 99 to the
steam cooker 90. The prewasher 12 may use water which is
warm, hot, or cold, but preferably using the Jiff-Wash
system described previously, a cold water rinse is used.
A cold water line is available to the prewasher 12, but
is not shown in FIG. 17.
If desired, hot water input 22 may provide hot
water-to--the-prewashers either for use in prewashing or
for cleaning the apparatus. Conveyor 16 transports food
granules through the presteamer 20, where they are
deposited into buckets 27, and there they receive the
dispenser line mixture 34. Hoiler 28 provides steam
SU$S7iTUTE SHEET (RULE 26)
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. 46 .
along steam line 49 to both the steam cooker 90 and tc
the heat exchanger 24.
Steam is provided from the boiler to the presteamer 2
along steam line 49 as seen in FIG. 17.
Further, steam cooker 90 may excrete "used"
recirculated water 37, which proceeds along steamer ~;irain
line 37, to be filtered and then ultimately either reused
or drained from the system. ~ne of the key features of
this invention relative to the abilities of reuse water
efficiently is the discovery of the water clarity that is
achievable for the water exiting the cooker at line 37.
It is believed that this is achieved as a result of two
things primarily; the use of the pre-steamer step and the
overall optimal supply of water in a proper temperature
and volume manner so as to avoid the leaching out of
loose starch molecules by providing water in quantities
that are coordinated to roughly the amount that the rice
can absorb at a particular point in the process. The
temperature maximum is important because if it is too
high, then starch damage (3.e., the release of free
starch and the undesirable gluing effect) may occur.
The food granule slurry departs the steam cooker -
90 along conveyor line 38, to the rotary dryer 32.
Vertical dryer 15 and bed dryer 14 are also seen in FIG.
17, with dashed lines to indicate that they are optional,
and not required in the present invention.
Using the recirculation in the present invention,
the amount of water used per pound of rice produced may
be greatly reduced. In the operations of the present
food- processing system, the water conten~of--rice as it
exits the steam cooker is typically between about 50 to
60% water. Rice is typically about ~0% to 50% water as
it comes out of the buckets 27 and proceeds to the steam
cooker. After cooking, and in the drying stage, the
percentage of water after the first stage of drying
suss~m sH~z t~u~~ 2~~
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(rotary drying) is about 20% water, but this percentage
will vary depending upon the product.
The present system resulits in the amount of water
applied or excreted being minimized, to a level of less
than about 3 to 1 by volume.
If the rice is provided ito a bed dryer following
rotary drying, the water content may be reduced to about
12%. If further drying is required or desirable, the
water content of the rice may be. reduced in a vertical
dryer to as little as about 6% water. Different rice
products will utilize different percentages of water and
it should be noted that the greater the amount of
moisture reduction achieved, the more expensive the
drying process will be in terms of energy consumption.
Obviously, numerous possibilities are available .
for the recirculated water in the present invention, and
the most efficient use of recirculated water will depend
upon the cooking conditions, the type of food granules
processed, and in the case of rice, will depend upon the
variety of rice, and whether it is short grain rice, long
grain rice, parboiled rice, etc.
For example, the examples below use only three
zones for drying (3.e., zone 1, zone 2 and zone 3;
wherein zone 1 is the closest to the entrance of the
dryer, zone 2 is next, and zone 3 is the furthest from
the dryer entry point). Additional drying zones might be
used in other embodiments. Also, the air velocities in
the drying zones are in the range of about 2500-3500 feet
per minute, preferably about 2500-2800 at the air blower
g0. 5~~ and 3000-3500 feet per minute within ~e..rotating
barrel.
Examble 1
The following example provides the preferred
processing conditions for practising the present
SUBSTTTUTE SHFEt (RiJLE 26)
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~ 48
invention using precooked, milled, parboiled, white long
grain rice as the food granule to be cooked. Of course,
these processing conditions may be varied for different
varieties of rice or for food granules which are not
cereal grains, such as vegetables or other food granules.
Further, the specifications below may be varied even for
milled white long grain rice if certain other
characteristics are desired in the final end product.
In the washing step, it is preferred in this
example that the washing occur for a period of about 30
seconds, with the ambient temperature of the washing
water at approximately 25°C. The moisture range of the
rice after washing is in the range of approximately 16%
to 18% water.
In the presteaming step, a 15 minute pre-steam is
provided to the rice, with ambient pressure, to achieve a
moisture range of the rice of approximately 22% to 25%
water.
The steeping step occurs for approximately 15
minutes as the rice moves along the conveyor in buckets
27, using water which is at a temperature of about 8~°C.
The moisture range achieved during the steeping is a
range of approximately 56% to 58% water. The charge of
rice used in each container is agproximately 15
kilograms, using about 22 liters of water in each bucket
far the steeping step.
In the steam cooker 90 (see FIGS. 2A-2Cj, the rice
is cooked for approximately 15 minutes at ambient
pressure, achieving a moisture range of about 59% to 60%
water
After steaming, the rice is transported in an
aqueous environment for about 30 seconds using water of
ambient temperature (about 25°Cj, and achieves a moisture
content of about 62% to 63% water. The transport occurs
by pumping to a dewatering device (vibratory drainerj.
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The rice is transferred to the vibratory drainer, and
into the rotary dryer. The temperature of the first zone
is about 250°C, while the temperature in the second and
third zones is about 195°C. The air velocity is a
variable that may affect drying temperature. The
retention time of the rice within the barrel of the
rotary dryer is about 2-1/2 minutes. This is the time
which elapses between the time the rice enters the barrel
and the rice exits the barrel by bouncing over the
adjustable lip plate 400 at the distal end of the barrel
within the rotary dryer. The moisture range of the rice
as it exits the rotary dryer is at a level of about 20%
to 22% water.
After the rice exits the rotary dryer, it proceeds
to a bed dryer for a drying time of about 5-7 minutes.
This drying occurs at a temperature of abaut 100°C, and
the rice achieves a moisture range, after drying, of
about 9% to 1l% water. The end groduct is a precooked
rice requiring about 5 minutes to prepare.
The conditions in these examples are provided as
examples only, and they should not be construed to limit
the invention in any way.
Examg,le 22
In a second example, a five minute, precooked,
milled, white, long grain rice is used as the product to
be cooked. In order to prepare the rice, the
temperature, time, and moisture ranges provided by below
are believed to be preferable. Nevertheless, different
varieties of rice, and different processing conditions
may be employed to achieve a product with different
characteristics.
First, parboiled rice is provided, and is
prewashed for approximately 30 seconds using water Which
is ambient temperature, to achieve a moisture range of
~sr~tur~ sNE~~r tRU~ zs~
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rice which is approximately 16% to 18% water. The rice
is then presteamed far about 10 minutes. This achieves a
rice with a moisture content of about 22% to 23% wate:.
Tb~;::.a rice is then steeped in buckets, as disclosed he~~ n,
5 fog about 10 minutes, at approximately 80°C. The
moisture range achieved after steeping is approximately
50% to 52%. The rice is then stem cooked for about 10
minutes in the preferred steam cooker of the present
invention. In this case, the steam cooker would be the
10 preferred steam cooker as seen in FIGS. 2A-2C. The rice
is then steam cooked at 150°C, and achieves a moisture
level of about 53% to 55% water. The rice is then
transported in a water slurry, which requires about 15
seconds, at ambient temperature, achieving a moisture
15 level of about 58% to 59%~
The rice is then provided to a rotary dryer for
two to three minutes at an air temperature which varies
between 195°C and 250°C. In the rotary dryer, zone 1 is
operated at 250°C (the zone nearest-the dryer entrance ,
20 and zones 2 and 3 are operated at 295°C, with total
retention time in the dryer of about 2.5 minutes. The
rice is then at a moisture level ranging from 22% to 25%~
The rice is then provided to a bed dryer for 5 to
minutes, at a temperature of about 100°C. The moisture
25 level achieved after drying in the bed dryer is about 9%
to 11%. As a final product, a 5 minute, precooked, white
instant rice is produced which is capable of a five
minute simmer cook by the consumer.
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Examgle 3
In a third example, a starting material of milled,
white, long grain rice is provided for processing. It
may be processed in the following example to produce an
instant, white, long grain rice with a preparation time
of about 7 minutes, and with a firmer cooked texture
which is characteristic of European-style marketed rices.
First, milled, white, long grain rice is prewashed, as
described previously, for 30 seconds using water which is
at ambient temperature (about 25°C). The rice then
achieves a moisture range between about 16% and 18%
water. The rice is then steam cooked for approximately
10 minutes at ambient pressure, which results in a
moisture range between 22% and 23% water. That step is
followed by steeping of the rice for 10 minutes using
water of 80°C (176°F). A moisture level of between 50%
and 52% is achieved. The temperature should be
coritroiled during the steeping, and a 15 kilogram charge
of rice is utilized with a 22.5 liter quantity of water.
The rice is then steam cooked for 10 minutes at ambient
pressure to achieve a moisture range of between 53% and
55% water.
The rice is then transported from the steam cooker
towards the drying apparatus for' a period of time which
is about 3A seconds, using ambient water temperature of
about 20°C to 25°C. The moisture range of the rice at
this point in the processing is between about 58% and 59%
water.
__._ _.__ _ __ In this- embodiment, . a--glow cTrying -process is
preferred, to produce a cooked texture which is
characteristic of European-type ;rices. The drying
proceeds for about 30 minutes at approximately 75°C, to
achieve a moisture level of between 9% and 11%. The
rotary dryer is used, but is not required for this end
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product. The texture produced by this method requires a
low drying temperature, as for example, 75°C as provided
in this particular example. The product produced is an
instant, white, long grain rice with a preparation time
of about 7 minutes and with a firmer cooked texture.
Example 4
In the fourth example, the rice cooked is a brown,
long grain rice, and it produces an end product which
comprises an instant, brown, long grain rice, with a
preparation time of about 10 to 12 minutes. Further, if
softer texture is desired, a 12 minute preparation time
is recommended, however, this example provides a rice
with a preparation time that is preferably about 10
minutes.
First, the rice is prewashed for 30 seconds with
an ambient water temperature, to produce a moisture
content of the rice between 14% and 16%. The rice is
then presteamed for 18 minutes at ambient pressure.
moisture level of about 18% to 20% is achieved.
The rice is then steeped for 18 minutes at 80°C
(176°F). A moisture range of between 42% and 45% is
achieved after the steeping step. The rice is then steam
cooked for 18 minutes at ambient pressure, to achieve a
moisture range of 50% to 55% water.
The rice is then transported, by way of water, for
about 30 seconds out of the steam cooker and to the
drying apparatus. The moisture range at this point is
58% to 59% water.
The rice i~ then dried in the rotary dryer, using
dryer temperatures in zone 1 (the zone closest to the
inlet of the dryer) of 230°C. Zone 2 is at a temperature
of about 195°C, and zone 3 is also at a temperature of
about 195°C. The moisture level of the rice after rotary
drying is about 15% to 18% water.
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The rice is then provided to a beef dryer for a
drying time of between 5 and 7 minutes at 100°C (212°F).
The moisture content of the rice after bed drying is
between 9% and 11%. The product of this particular
example is an instant, brown, long grain rice with a
preparation time by the consumer of about 10 to 12
minutes.
Modifications of the apparatus and methods
disclosed in this patent application could be conceived
by a person skilled in the art, without departing from
the spirit or scope of the invention. For example, it is
contemplated that the present invention could be utilized
whereby a different number of heating sections in the
rotary dryer or a different configuration of the cooking
segments in steam cooker 90 may be established.
It is anticipated that different types of steam
cookers could be established which utilize either
vertical means of feeding food granules by way of gravity _
inducement, or a horizontal method might be established
whereby food granules may be cooked and fed through in a
horizontal manner. Further, it is obvious that
variations could occur in the method and apparatus of
recirculating water in the present invention to most
advantageously and efficiently utilize the least amount
of input water and excrete the least amount of waste
water. The present invention is not limited to the
disclosure in this regard, and other arrangements could
be easily conceived. Further, tl'e temperatures,
pressures, and cooking conditions disclosed herein are
disclosed as the-preferred and alternate embodiments, but
cooking could occur using temperatures, pressures, and/or
methods that ate not disclosed in the present
specification, but still fall within the scope of this
invention. Additionally, although the disclosed
apparatus and methods have been described primarily for
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use with rice, these apparatus and processes are suitable
for use with other food products, as well. The present
disclosure is intended to cover all such modifications as
fall within the scope of the appended claims, including
equivalents.
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