Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02490194 2004-12-15
METHOD AND SYSTEM FOR PRODUCING
A DEHYDRATED WHOLE FOOD PRODUCT
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is in the field of food products and, more particularly,
directed
to a method and system for producing a dehydrated food product, including
whole
cooked bean (and other such similar) products in such a way as to preserve the
structural integrity of the bean which, in turn, helps provide a food product
having
significantly enhanced texture and quality.
2. Back rg o
The prevalence of fast-food style establishments in recent years has been
accompanied by an increased demand for reconstitutable food products, such as,
for
example, dehydrated refried beans. From an economic point of view, such
products
have several advantages. For example, each establishment can buy and store the
product in bulk quantities without the risk of spoilage. Also, since the
product is
normally reconstituted in a matter of minutes by adding only water, there are
savings
in time, energy, and labor associated with the use of these products. Finally,
since
there is no need to continually prepare the food product in the conventional
manner
(i.e., to make the food fresh, and on a daily basis), there is also no need
for each
establishment to keep extra equipment (e.g., cookware, etc.) on the premises.
As
such, methods have been devised to produce reconstitutable food products that,
ideally, could be prepared very quickly, and would have the taste, texture,
and
appearance of their conventionally-prepared counterparts.
Current methods and apparati for producing such food products and, more
specifically, refried bean products, require that one consider various
factors. For
example, to satisfy the requirement that the raw beans be mixed as they are
hydrated
and, also, as they are cooked, a number of the methods presently known employ
rotating vessels. Vessels that rotate are used so that the beans can be
contacted with a
small amount of water that is diminishing as the water is absorbed by the
beans.
Controlled amounts of water are used during the cooking process in hopes that
at the
end, little or no water remains - only the cooked, hydrated beans. This is
difficult to
achieve, and the art has searched for various methods, as excess water can
result in
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yield loss (some of the beans will dissolve into the water) and/or a pasty
product that
is difficult to further process and dry.
Merely placing the beans in water has other shortcomings. For example, such
a method can result in some beans becoming too soft, while others do not
become
properly hydrated. Further, prior art vessels are generally quite bulky, which
not only
translates into added and more-frequent maintenance requirements, but also
makes it
more difficult to achieve economies of scale. Further still, generally, in
many prior
art vessels only a small amount of beans can be treated. In other words, to
achieve the
benefit of a small water-to-bean ratio, rotating vessels of particular
configurations and
having limited capacities were used. Even then, it is difficult to control the
water
absorption into the beans.
Yet other shortcomings relate to the starting materials that are used. In a
typical prior art process for preparing refried beans, dry, raw beans are
placed into the
vessel, and a small quantity of water is added. Unless the vessel rotates, the
beans on
the top of the pile could absorb a different amount of water as compared to
the beans
at a position lower down. Further, as the water level in the vessel decreases,
yet
further non-uniform water absorption throughout the beans could result. It is
known
that raw beans typically have an initial moisture content in the range 6% -
14%.
However, current methods have difficulty using a batch of raw material that
spans this
entire range because the disparity in initial moisture levels exacerbates the
variations
in water absorption during hydration with small amounts of water, which would,
in
turn, result in a non-uniform final product. As such, in order to use many
prior art
methods and apparatuses, the practitioner is limited to using rotating vessels
and to
batches of raw materials, each of which falls within a small sub-group of
initial
moisture-content ranges (e.g., those in the 6-8% range, or those in the 10-12%
range,
etc.).
An additional phenomenon, which is addressed only partially by current
methods and apparati, is the existence of a proportion of "hard" beans in a
given batch
of raw beans. In this regard, the relevant literature has identified two types
of bean
"hardness". In the first, a condition of the cotyledon prevents absorption of
water by
the bean seed. Thus, studies have found that certain beans fail to absorb
water even
though the seed wall was scarified or removed. These studies further suggest
that this
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condition may be caused by enzymic changes during the storage of seeds in damp
atmospheres at high temperatures.
The second, more-frequently encountered type of "hard" bean is one in which
the "hardness" is due to hardshell, i.e., an impermeable seed wall. As has
been
recognized in the art, because untreated hard-shell beans do not soften
properly during
cooking, when such beans are processed for food, the resulting food product
may
exhibit poor textural quality. More specifically, in preparing a cooked bean
product,
the hard-shell bean portion of the initial raw materials will generally remain
hard
through the soaking and cooking processes. As such, when the hard-shell beans
are
left untreated, the final (cooked) product will have an inconsistent quality.
On the
other hand, over-soaking and/or over-cooking of the entire bean batch in order
to
render the untreated hard-shell beans palatable may cause the remaining (non-
hard
shell) beans to disintegrate, resulting in a final product that has a mushy
consistency.
Irrespective of the source of the "hardness" in beans, it is well known that
lower moisture beans (i.e., those with a moisture content of less than about
10%) have
a greater tendency to be classified as "hard". Since beans are only harvested
once a
year, the beans that have been stored for more than about 6 months tend to dry
out and
suffer more from the "hard bean" phenomenon, causing major product quality
variation.
In light of the above, the prior art has suggested various means of addressing
the "hard bean" phenomenon. One such means involves heat treatment, whereby
the
beans are steamed, or treating with hot water, prior to storage and/or
soaking.
However, such treatment does not guarantee elimination of hard-shell beans.
Alternatively, U.S. Patent No. 4,871,567 (the "567 patent") suggests
"tempering", whereby, once the beans have been washed and drained, they are
permitted to simply sit for a period of ''equilibrium" which lasts four or
more hours.
This procedure, however, introduces a relatively long period of downtime, thus
making the overall process of producing a dehydrated reconstitutable food
product
very time consuming. In addition, as is recognized in the '567 patent, sitting
food
products often lend themselves to deleterious effects, such as souring or
other
undesirable flavor changes. Such deleterious effects may only be dealt with by
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introducing additional processing steps, which makes the overall process even
more
complex and time consuming and, as a result, reduces overall processing
efficiency.
In the current state of the art, there are also disadvantages associated with
the
end product itself (e.g., with the dehydrated bean product). For example, even
though
one goal of dehydrated food products is to allow for rapid water take-up at
reconstitution, this goal is only partially met in current dehydrated bean
products. As
is known in the art, most current methods produce products that are either in
the shape
of small pellets or in the shape of flakes or in the shape of fine powder. In
the case of
pellets, because of the way in which the final product is prepared, typically
only a
small portion of the surface area of each pellet (i.e., typically, the two
ends of each
pellet) provides areas through which water can easily be absorbed; the
remainder of
the pellet's outer surface is inefficient in absorbing water. Flakes, on the
other hand,
due to their method of manufacture, have a harder outer surface and are
generally
treated with oil on their surface, which is a water repellent, so that water
take-up upon
reconstitution is actually slower than it may be otherwise. Therefore, in both
cases,
water absorption rates are not optimal.
Moreover, upon reconstitution, many of the dehydrated products currently
available turn into paste-like, or other similar, uniform compositions, where
there is
generally a lack of texture in the food. This is especially true with methods
and
apparatuses that produce a granular, rather than a pelletized, or flake-like,
dehydrated
product. In addition, regardless of the actual shape and form of the final
product,
there is no simple provision in existing methods and apparatuses for varying
(i.e.,
custom making) the texture of the final product as desired.
Reference is made to U.S. Patent Nos. 4,676,990, 4,735,816, and 4,871,567 as
further examples of the prior art. These references illustrate various bean-
making
processes, but all have a number of shortcomings. For example, in the '990
patent, a
pelletized product is produced by particularized processing steps and related
apparatus. In the '816 and '567 patents, a thin, flake-like product is
produced by
means of yet other particularized processing steps and apparatus. These
processes are
complicated and the final products are only marginally close to refried beans
made to
have a pleasant texture with a desired amount of bean particulates.
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To address some of the issues relating to the lack of adequate texture in the
reconstituted food, attempts have been made in the prior art to add dehydrated
whole
beans to the aforementioned products. However, such attempts have been met
with
difficulties as dehydration of cooked whole beans has generally been
accompanied by
a considerable amount of "bird mouthing".
Bird mouthing, also referred to as "butterflying", is a phenomenon wherein the
whole bean splits along its two halves and opens during the dehydration
process. It is
believed that bird mouthing is caused by a differential rate of drying between
the bean
skin and cotyledon, such that, during the dehydration process, the bean skin
dries
more rapidly than the cotyledon, and thus, contracts (a condition which is
referred to
as "case hardening"). As dehydration continues, the slower-drying cotyledon
develops internal vapor pressure to an extent where the pressure ruptures the
skin and
causes bird mouthing.
Reference is made to U.S. Patent Nos. 3,290,159 and 4,871,567 as examples
of the prior art's attempts to reduce the amount of bird mouthing in
dehydration of
whole beans. For example, the ' 159 patent discloses a two-stage dehydration
process,
wherein the first stage involves a slower moisture-removal process, and the
second
stage involves a more rapid dehydration process. Both stages of the disclosed
methodology are directed to drying using conventional air dryers. Similarly,
the '567
patent discloses a dehydration process comprising two or more "stages".
However, in
contrast to the '159 patent, the '567 patent teaches a method involving
incremental
decreases, rather than increases, in the amount of heat supplied during the
dehydration
process. Nevertheless, neither methodology seems to have resolved, to an
appreciable
degree, the problem of bird mouthing.
An additional drawback associated with the process disclosed in the '159
patent is that, in order to be effective, the process calls for slow drying
rates. Such
slow drying rates translate into relatively long drying times (e.g., on the
order of 4 - 6
hours) which, in turn, result in low levels of throughput per unit time.
Similarly, the
process disclosed in the '567 patent calls for an initial period of high-
humidity drying
which, again, results in longer drying times. This is especially true when
convective
heating is utilized to dry the beans since convective dehydration efficiency
drops off
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drastically during the latter stages of drying particulate material when
moisture
diffusion from the center of the particle controls the drying rate.
Food manufacturers have also used equipment andlor forms of energy other
than conventional air dryers to produce dehydrated food products. In this
regard,
reference is made to U.S. Patent Nos. 4,073,952 and 6,197,358. The '952 patent
discloses a method of making dehydrated potatoes, wherein the method includes
drying pieces of potato by exposing them simultaneously to microwave energy
and to
hot air. The hot air is enriched with moisture to maintain an average humidity
of at
least 83% in the oven during most of the drying period. In addition, about 10-
50% of
the energy used for drying is provided by moisture-enriched air that is heated
to
between 75 and 255 °F and, typically, to 100-150 °F.
However, being unrelated to the production of dehydrated bean products, the
'952 patent does not address bird mouthing at all. Rather, it teaches a
combination
microwave/hot air drying process in order to minimize discoloration and loss
of flavor
for potato pieces. Similarly, the '358 patent is related to a process in which
microwave energy may be used during the production of dehydrated potato
products,
but not during the drying step.
The features and advantages of the present invention will become more
apparent through the following description. It should be understood, however,
that
the detailed description and specific examples, while indicating particular
embodiments of the invention, are given by way of illustration only and
various
modifications may naturally be performed without deviating from the spirit of
the
present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows an illustration of a hydration/cooking vessel and rotatable
member of an
apparatus that may be used in the practice of an embodiment of the invention.
FIG. 2 shows a cross-sectional view of the vessel and rotating member of FIG.
1,
taken along line II - II.
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FIG. 3 shows an illustration of a shaft and rotatable member of an embodiment
of the
cooking vessel shown in FIG. I.
FIG. 4 shows an illustration of a channel and forming conduit of an apparatus
that
may be used in the practice of an embodiment of the invention.
FIG. 5 shows a cross-sectional view of the channel and forming conduit of FIG.
4,
taken along line V - V.
FIG. 6 shows a condensed flow-chart format of an embodiment of the invention.
FIG. 7 shows a condensed flow-chart format of an alternative embodiment of the
invention.
FIGS. 8A - 8C show various cross-sections of a sheet of textured material
according
to an embodiment of the invention.
FIG. 9 shows an illustration of a hydration vessel that may be used in the
practice of
an embodiment of the invention.
DETAILED DESCRIPTION
An embodiment of the present invention is related to a method or process for
producing a reconstitutable, dehydrated food product, which may be practiced
by the
use of apparatus comprising a stationary hydration vessel, a stationary
cooking vessel,
a chopping system, a forming mechanism, and a drying system.
It is well known that food products, such as beans, soften and become fragile
as they are hydrated and cooked, making their subsequent processing difficult
and the
dehydrated product variable in quality. As such, embodiments of the present
invention are directed towards stationary processes that minimize (or
completely
eliminate) movement of the beans.
In order to cook raw beans (with an initial moisture content in the range 6% -
14%, e.g.), they have to be uniformly hydrated either prior to, or
simultaneously with,
cooking. Unfortunately, uniform hydration is difficult due to the variable
presence of
"hard" beans that are difficult to hydrate.
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Surprisingly, it has been discovered that these "hard" beans tend to float in
water at temperatures of about 200 °F. Thus, contacting beans with hot
water, as is
frequently done to accelerate their hydration, actually makes the hydration
more
difficult and variable since the "harder" beans float to the water/air
interface.
However, if the raw beans are maintained below the water/air interface by, for
example, a restraining screen, then much more uniform and rapid hydration
occurs.
Of course, it is well known to hydrate beans at low temperatures, in which
case the
issue of floating "hard'' beans is eliminated. However, such low-temperature
hydration methods require that the beans be sedentary in water for prolonged
periods
of time (e.g., 10 - 12 hours), which renders such traditional hydration
methods
commercially unfeasible.
In order to hydrate variable-quality (i.e., with respect to "hardness") beans
in
as gentle a way as possible, a stationary hydration vessel is used that may be
generally
vertically elongated and includes means for maintaining the beans below a
waterlair
interface, as well as means (e.g., standard pump, tubing, and inlet valve) for
introducing and circulating a wetting liquid through the vessel and the beans.
At the beginning of the hydration step, raw cleaned beans are placed within
the vessel; the beans are maintained below the water/air interface (i.e.,
below the
water, or wetting liquid, level) throughout a predetermined hydration period.
Upon
termination of the hydration period, beans that have been adequately hydrated
generally sink to the bottom of the vessel and are removed. "Harder" beans,
however,
that tend to buoy up towards the upper portion of the hydration vessel are
captured
(e.g., by means of a mesh screen) during hydration, and if still "hard",
removed at the
end of the hydration period and optionally returned to the vessel for
additional
hydration with a subsequent batch of raw beans. In addition, after each
hydration
period, a "broth", comprising the unabsorbed portion of the wetting liquid and
a
proportion of bean solids is removed from the vessel. Optionally, the broth
may be
further processed to separate the bean solids therefrom, and some or all of
these bean
solids may be returned to the beans at a later stage in the process.
The stationary cooking vessel is equipped with a perforated, rotatable
internal
baffle which may be rotated periodically to ensure contacting, if necessary,
of all
beans or other foods with a small and continuous diminishing quantity of
water; the
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baffle holes ensure that fluids within the vessel are exchanged freely between
the two
chambers of the vessel as defined by the baffle. Once cooked, the beans are
transferred to the chopping system, wherein they are urged through a channel,
comprising a rotating blade that chops, and a perforated plate that re-sizes,
the beans
into a texturized composition. The blade speed and the size of the holes in
the
perforated plate can be changed in order to achieve different textures within
the
composition. The latter is then treated in a forming mechanism, comprising a
shaped
conduit, wherein the composition is formed into a generally flat sheet, which
is then
treated so as to produce an improved reconstitutable dehydrated bean product.
In
certain embodiments, the generally flat sheet may be ribbed, or ridged, on
either, or
both, of its top and bottom surfaces.
The stationary cooking vessel of the present invention has significant
processing advantages. First, since the vessel is stationary, it is relatively
simple to
construct large units which result in substantial economies of scale. Second,
by using
a horizontal cooking vessel with a perforated internal baffle having a length
and width
that are substantially the same as the vessel, it is easy to assure that, when
needed
during processing, all of the beans are gently and continuously contacted with
a small,
and diminishing quantity of liquid.
Indeed, under certain embodiments of the present invention, the perforated
internal baffle can be completely eliminated provided that the beans have been
adequately hydrated prior to cooking. In this manner, movement of the beans
during
cooking is essentially eliminated.
Embodiments of the present invention are directed to a method of preparing a
reconstitutable, dehydrated food product by means of hydrating and cooking raw
beans, so that all of the cooked beans achieve a similar moisture content,
chopping the
cooked beans and forming the chopped beans into a flat sheet of texturized
composition, drying the sheet, and breaking the sheet into smaller pieces.
The above-described process results in a dehydrated bean product that absorbs
water faster and more uniformly upon reconstitution. Also, after the raw beans
have
been hydrated, the broth can be partially, if desired, removed from the
hydration
vessel, thus eliminating some flatulent sugars from, and improving the
digestibility of,
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the final bean product. Moreover, salt, oil, colorant, and other flavoring may
be
added during the chopping, or other steps, of the above-described process.
Finally, depending on the desired texture and chunkiness of the final product,
a portion of hydrated and cooked whole beans may be removed before the
chopping
step, and then added to the beans in a subsequent step, or after drying to the
final
product upon reconstitution. Alternatively, whole beans may be independently
hydrated, cooked, flavored, and dried, and then mixed with dehydrated small
pieces of
chopped beans produced separately. In yet another alternative embodiment, a
portion
of hydrated whole beans may be separately cooked, flavored, and dried, and
then
mixed with dehydrated small pieces of chopped beans produced separately from
the
remainder of the hydrated beans. In yet another alternative embodiment, the
hydrated
whole beans may be cooked, flavored and dried. Such product can then be used
where quickly reconstitutable whole beans are desired as needed.
Figures 1 and 4 show one embodiment of the apparati which may be used to
practice the invention. As shown in these figures, a stationary vessel 10
comprises a
vessel shell 12, and a central shaft 30. Although the figures show that the
vessel 10
has a substantially circular cross-section, this is done for purposes of
demonstration
only, and it is intended that the invention encompass other vessel
configurations as
well.
The vessel 10 is also equipped with a solid-blade baffle 20, which is attached
to, and is rotatable around, shaft 30. In one embodiment, baffle 20 has a
length and
width that are substantially as long as the length and width, respectively, of
the vessel
10. Therefore, in the embodiment of Figures 1 and 2, the width of the baffle
20 is
substantially commensurate with the diameter of a cross-section of the vessel
10. To
ensure proper operation, a clearance of less than 3/16 inch is maintained
between the
inner surface 18 of the shell 12 and an edge 24 of the baffle 20, as well as
between an
end 28 of the baffle 20 and an end 11 of the vessel 10.
As is shown in Figure 2, at any point in time, the baffle 20 divides the inner
space of the vessel 10 into two chambers, 14 and 16, where each chamber is
defined
substantially by the space between the inner surface 18 of the vessel shell
12, and a
wall 26 of the baffle 20. The solid-blade baffle 20 has transverse holes 22
(shown in
CA 02490194 2004-12-15
Figure 1, and by dashed lines in Figure 2) which, while large enough to allow
fluids
within the vessel 10 to travel between the chambers 14 and 16, are small
enough to
keep the vessel contents 100 separated on each side of the baffle 20.
In one embodiment, the vessel 10 may be employed both to hydrate raw beans
and to cook the hydrated beans. As will be explained in detail below, when
used in
the latter capacity, the vessel 10 is transformed into a pressure cooker,
using steam to
cook the beans. To achieve uniform steam injection into the chambers 14 and
16,
steam is forced through the shaft 30, and enters each chamber 14, 16 through
steam
outlets 32 which are arranged along the length of the shaft 30 (Figure 3).
However,
steam can also be injected into the vessel through other suitably placed
entrances to
the vessel.
In a preferred embodiment, a separate, stationary hydration vessel 200 is used
to hydrate the beans, which are then transferred to vessel 10 in order to be
cooked (see
Figure 9). Hydration vessel 200 is generally vertically elongated, with a top
end 210
and a bottom end 220, and includes means (such as an inlet valve or similar
structure,
e.g., at its bottom end 220) for introducing a wetting liquid into the vessel
to establish
a liquid level 240 such that all of the beans are immersed into the liquid.
Thus, the
wetting liquid may be pumped into the hydration vessel 200 such that the
liquid is
circulated through the beans within the vessel 200 for a predetermined
hydration
period which, typically, may last between 40 and 150 minutes.
Below the liquid level 240, the hydration vessel 200 is equipped with means
for capturing harder beans that may not hydrate adequately during the allotted
hydration period and, as such, buoy up towards the upper end 212 of the vessel
200
(i.e., "floater" beans). The capturing means may include, for example, a mesh
screen
230, or similar structure. Below the capturing means 230, the hydration vessel
200
includes means, such as a release valve 250, for removing the floater beans
from the
vessel 200 upon termination of the hydration period.
On the other hand, upon termination of the hydration period, beans that have
been adequately hydrated and, as such, have generally sunk towards a lower
portion
222 of the vessel 200 may be removed through outlet means (e.g., an outlet
valve or
similar structure) which may be placed at the bottom 220 of the vessel 200. In
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addition, after each hydration period, a "broth", comprising the unabsorbed
portion of
the wetting liquid and a proportion of bean solids may also be removed from
the
vessel 200 through the same, or an additional, outlet means (not shown), which
may
also be placed at the bottom 220 of the vessel 200.
Experimental results surprisingly indicate that "hard" beans tend to float in
water with temperatures in excess of about 200 °F. As such, using the
above-
described hydration vessel and carrying out the above-described hydration
process,
especially at temperatures within the range 180 - 210 °F, is
advantageous as it ensures
that: ( 1 ) all of the beans are immersed in water throughout the hydration
period; (2)
"hard" beans can be identified and recycled until suitable for cooking, thus
allowing
efficient use of all of the beans and substantially eliminating hard beans
from the final
bean product upon reconstitution; and (3) hydration of the beans can be
accomplished
in a quick and gentle fashion, thus minimizing any damage to the beans.
In one embodiment, the hydration vessel 200 may have a circular cylindrical
configuration, with a height of about 10 feet, and a circular base having an
inner
diameter of about 3 feet. However, other configurations and dimensions may
also be
used in practicing the invention.
In addition, bean solids that are dissolved in the broth that remains at the
end
of the hydration period can be recovered (e.g., by evaporation, filtration,
spray drying,
etc.) and added back to the cooked beans either in concentrated or dried form.
Alternatively, the broth itself (or the unabsorbed portion of the wetting
liquid therein)
may be added to water and introduced into the hydration vessel for hydration
of a
subsequent batch of beans, or flavors can be recovered (e.g., by steam
stripping) from
the broth for back addition to the cooked and chopped beans (see below).
It is also mentioned that, although, in principle, the beans could be hydrated
by
just allowing them to soak in the water for a period of time, experience has
shown that
this practice results in non-uniform water absorption by the beans. That is,
over time,
as the beans on the top of the pile absorb water, the water level in the
vessel
decreases, which causes non-uniform water absorption throughout the pile of
beans.
On the other hand, it is known that raw beans typically have an initial
moisture
content in the range 6% - 14%. However, given their non-uniform hydration
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procedures, prior-art methods cannot use a batch of raw materials that
includes beans
and legumes from this entire range because the disparity in initial moisture
levels may
exacerbate the variations in water absorption during hydration, so that the
result
would be a highly non-uniform final product. As such, for every batch of raw
materials, the prior art is limited to using raw beans that fall within a
small range of
initial moisture content, e.g., 6-8%, or 12-14%. The present invention,
however, is
not so limited.
In a preferred embodiment, the hydrated beans can then be cooked in a
stationary cooking vessel 10 by simply placing them on the upper side of the
baffle 20
when the latter is in the horizontal position. Since there is no need to have
any further
water in the vessel 10 while the beans are being cooked, it is not necessary
to rotate
baffle 20 during the cooking step. The hydrated beans are cooked using direct
steam
injection. Alternatively, the separately hydrated beans can be pressure cooked
in a
vessel with no rotatable baffle, provided the beans are sufficiently elevated
off the
bottom of the cooker to prevent the steam condensate from contacting the lower
beans.
An option, at this point, is to add salt or other flavoring, colorant, oil
and/or
similar additives to the cooking vessel 10. Also, either as a substitute for,
or a
supplement to, this option, oil, colorant, salt, and/or other flavoring may be
added at
various other steps within the process (e.g., after cooking or during the
chopping
step).
In order to cook the beans, steam is directly injected into the vessel 10 and
chambers 14 and 16, such that the vessel 10 is pressurized above atmospheric
pressure, and the beans are cooked at a temperature in the range 228 °F
- 270 °F and
pressure in the range 5 psig - 25 prig for a predetermined cooking period.
During the
cooking step, the cooking vessel 10 remains stationary, and the baffle 20 may
either
remain stationary, or rotate around the central shaft 30 for a minimal number
of times.
However, if the baffle 20 rotates, it is possible to drain any water
condensate off the
bottom of the cooker prior to rotation, so as to further minimize any contact
of
cooking beans with water.
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It has been found that, when the baffle 20 is held stationary during at least
a
majority of the cooking period, there are no beans that are always in contact
with
water from condensed cooking steam that may gather at the bottom of the
cooking
vessel 10. This, in turn, results in beans that are uniformly cooked. In
addition,
reducing bean movement, or agitation, such as the kind that may be caused by
frequent rotation of the baffle 20, allows whole cooked beans to be produced
with
minimal crushing.
At the end of the cooking step, the beans are removed and transferred to a
channel 40 having a proximal end 41 and a distal end 42 (see Figures 4 and 5).
Within channel 40, the cooked beans are urged towards the distal end 42 via a
piston
or other suitable mechanism, such as a rotating shaft with advancing frights.
As the
beans are urged forward, they are chopped by a rotating blade 50, which
rotates at an
angular velocity cu. The beans are then pushed through the holes 62 of a
perforated
plate 60, which is located distal to the rotating blade 50 and re-sizes the
chopped
beans as they travel past the plate. In this way, a texturized composition is
created,
wherein the texture, or chunkiness, of the composition (and of the final bean
product)
is determined by the angular velocity w of the blade 50 and the hole sizes of
the plate
60. Therefore, the present invention offers the capability of varying the
texture of the
final bean product to a desired consistency by changing the blade angular
velocity ca,
the size of the plate holes 62, or both.
The chopped beans are next fed through a forming conduit 70. As shown in
Figure 4, in a preferred embodiment, the inlet 72 of the forming conduit ?0 is
connected to the distal end 42 of the channel 40. However, this is not
required, as
long as the conduit 70 and the channel 40 are in flow communication, so that
chopped
beans exiting the channel from its distal end 42 flow into the forming conduit
through
its inlet 72. For example, the inlet 72 may comprise a hopper, or other inlet
configuration, that is situated within close proximity of; but not necessarily
connected
to, the channel 40. Regardless, once the chopped beans are in the conduit 70,
they are
urged towards the conduit outlet 74. The outlet 74 has a generally rectangular
cross-
section which may have ridges on its top and/or bottom surface(s), a thickness
T, and
a width that is considerably larger than T. Therefore, as the texturized
composition
exits the conduit outlet 74, it is formed into a generally flat, continuous
elongated
14
CA 02490194 2004-12-15
sheet of rectangular cross-section that may have ridges 99 on its top and/or
bottom
surface(s). Additives, such as salt, oil, flavorings, and/or colorants may be
added to
the beans during the chopping and/or forming steps so as to result in a
uniform
dispersion of these additives.
Figures 8A - 8C show various cross-sections of the sheet of textured material.
For example, where the outlet 74 of the forming conduit 70 has a rectangular
cross-
section of thickness T (see Fig. 4), a generally flat sheet of textured
composition is
produced that also has a generally rectangular cross-section, with thickness
T~ (see
Fig. 8A), where the magnitude of T~ may be slightly less than the magnitude of
T.
On the other hand, the outlet 74 may have ridges, or ribs, on its top and/or
bottom
surface(s). As shown in Figures 8B and 8C, this will result in a sheet of
texturized
composition that also has ridges (or ribs) 99 running longitudinally on its
top and/or
bottom surface(s).
It is noted that the cross-sectional configuration of the sheet of texturized
composition is generally determined by striking a balance between throughput
and
drying efficiency. That is, on the one hand, the thicker the sheet of
texturized
composition, the higher the amount of beans that can be processed for a given
speed
through the forming conduit 70. On the other hand, the thicker the sheet of
texturized
composition, the higher the required amount of time for exposure to heat (or
other
drying mechanism) which, in turn, translates into a slower processing speed--
or, put
another way, if the speed is kept constant, then a thicker sheet of
composition may not
be sufficiently dried. In this regard, experimental results indicate that, in
a preferred
embodiment, all sections of the sheet are typically less than about 1 /4 inch
thick.
The elongated sheet of texturized composition is next dried and then broken
up, or formed, into chunks, where each chunk may be approximately 0.25 to 0.50
inch
in size. In a preferred embodiment, the drying step is accomplished by drying
the
elongated sheet of texturized composition in a combination
microwave/convection
dryer, where the sheet is dried to a final moisture content of less than about
9-10%.
This drying arrangement provides for control over the characteristics (e.g.,
flavor) of
the final product, as well as a higher level of efficiency and throughput by
the overall
process. Thus, for example, during the drying step, the sheet of texturized
composition may be toasted (to enhance flavor) by adjusting the convection air
IS
CA 02490194 2004-12-15
temperature. On the other hand, the microwave-energy mode allows drying of
ribbed
sheets of texturized composition of a thickness greater than 1/2 - 5/8 inch in
relatively
short time periods.
Processing the beans as described above produces chunks of dehydrated bean
product that have rough, uneven, and porous edges. Moreover, each chunk has a
larger surface area containing these rough edges than do bean products
prepared
according to prior-art methods. This translates into pieces with porous edges
that take
up and absorb water much more easily and quickly upon rehydration than is
available
in the prior art. Generally, pieces having a thickness of 1/8 inch or greater
are within
the scope of the present invention, although the invention is not so limited
and other
thicknesses may also be employed in practicing the invention.
Figure 6 shows, in condensed flow-chart format, an embodiment of a method
of the invention. As shown in Figure 7, in a preferred embodiment, separate
portions
of beans, e.g., those destined to be chopped and those that are maintained
whole, are
processed separately and under different processing conditions (e.g., using
different
hydration times, different cooking temperatures, etc. to make the chopped
beans more
tender than the whole beans). Thus, in one preferred embodiment, while the
beans
destined to be chopped are processed as described above, the beans destined to
remain
whole are processed separately, and then mixed with the chunks. In an
alternative
embodiment, the chunks and whole beans can be kept separate and used as
desired in
that form.
In this regard, aspects of embodiments of the present invention are directed
to
a method of preparing a reconstitutable, dehydrated whole bean product in such
a way
as to preserve the structural integrity of the whole beans which, in turn,
would
significantly enhance the texture and quality of the final bean product
containing the
whole beans. As has been set forth above, such a method must address, and
significantly decrease, the amount of bird mouthing that is prevalent in
methods
currently existing in the art, without adversely affecting productivity levels
(i.e.,
throughput).
16
CA 02490194 2004-12-15
In one aspect, the above-mentioned goals are achieved by a method of
preparing dehydrated whole beans so as to preserve the beans' structural
integrity,
wherein the method comprises:
cleaning, washing, hydrating, and cooking raw beans; and
S drying the cooked beans in a combination microwave-convection heating
process, wherein the beans are dried by exposure to both microwave
energy and convective heating energy.
The above-mentioned goals are also achieved by a method of preparing
dehydrated whole beans so as to preserve the structural integrity of
substantially all of
the beans (i.e., less than about 25% by weight incidence of bird mouthing in
the
dehydrated product), wherein the method comprises:
providing a heating chamber for drying of cooked beans, wherein said
chamber includes means for continuously advancing the cooked beans
through said chamber; and
drying the cooked beans in said chamber by exposing said beans to both
microwave energy and convective heating energy.
In yet another aspect, the above-mentioned goals are achieved by a method of
preparing dehydrated whole beans so as to preserve the beans' structural
integrity,
wherein the method comprises: cleaning, washing, hydrating, and cooking raw
beans;
arranging the cooked beans into multiple bean layers; and drying said layers
of
cooked beans using microwave energy, convective heating, or both microwave
energy
and convective heating energy.
In another aspect, a method of preparing dehydrated whole beans so as to
preserve the structural integrity of substantially all of the beans comprises:
providing
a heating chamber for drying of cooked beans, wherein said chamber includes
means
for continuously advancing the cooked beans through said chamber; arranging
the
cooked beans into multiple bean layers; and drying said layers of cooked beans
in said
chamber using either microwave energy, convective heating, or both microwave
energy and convective heating energy.
17
CA 02490194 2004-12-15
Thus, embodiments of the present invention utilize microwave energy and/or
convective energy to efficiently dry cooked whole beans and minimize "bird
mouthing". As indicated by data collected from experiments, in a "dual-mode"
drying process, use of the microwave mode will heat water from inside each
bean,
thus minimizing case hardening, and use of the convective mode will "blow"
away
evaporated water.
In light of the various means of addressing bird mouthing, and with reference
to Figure 7, embodiments of the present invention are also directed to a
method for
producing a reconstitutable dehydrated chunky bean product so as to
substantially
eliminate hard beans from the bean product, the method comprising:
separately hydrating first and second portions of raw beans by
maintaining the entirety of said first and second portions
submerged in a wetting liquid for respective hydration
periods so as to obtain respective first and second
portions of unchopped hydrated beans;
separately cooking each of said first and second portions of
hydrated beans to obtain respective first and second
portions of unchopped cooked beans;
chopping said first portion of the cooked beans to form a
composition of a desired texture;
forming the texturized composition into a generally flat sheet;
drying the flat sheet of texturized composition;
forming the sheet into chunks;
drying the second portion of unchopped cooked beans using
microwave energy, convective heating, or both
microwave energy and convective heating energy; and
adding the dried second portion of unchopped cooked beans to
said chunks.
18
CA 02490194 2004-12-15
In an alternative embodiment, the method for producing a reconstitutable
dehydrated chunky bean product so as to substantially eliminate hard beans
from the
bean product comprises arranging the second portion of unchopped cooked beans
into
a stack of multiple bean layers, and then drying the layers using microwave
energy,
connective heating, or both microwave energy and connective heating energy
prior to
adding the second portion of unchopped cooked beans to the chunks.
It is noted that, in the above description, the designations "first" and
"second"
are used for identification purposes only and do not necessarily indicate an
order of
carrying out an embodiment of the invention. In addition, in alternative
embodiments, each of the drying steps may by accomplished by using microwave
energy, connective heating or a combination thereof.
As mentioned above, in a preferred embodiment, the beans destined to be
chopped are processed as described previously, and the beans destined to
remain
whole are processed separately. More specifically, the beans destined to
remain
whole are washed, cleaned, hydrated, and cooked separately from, but in a
similar
fashion to, the beans destined to be chopped. Thus, for example, the beans
destined to
remain whole are hydrated and cooked in the apparati depicted in Figs. 9 and
l,
respectively, using substantially the same steps, but a different
temperature/pressure/time profile, than that used for the beans destined to be
chopped.
Once cooked, the whole beans are arranged into a stack having multiple bean
layers, and then dried using microwave energy, connective heating, or a
combination
of microwave and connective energy. In a preferred embodiment, the stack of
beans
is at least 13/g inches high (containing at least 4 layers) and is dried using
a
combination microwave/convection dryer. As was noted previously in connection
with drying the sheet of texturized composition, the microwave energy input
allows
the drying step to proceed at high throughput rates. As is discussed more
fully herein,
adjustment of the convection air temperature, on the other hand, allows a
significant
degree of control over the rate of incidence of bird mouthing in the whole
beans.
Once the whole beans have been dried, they are mixed with the chunks (from
the first portion) to produce a dried refried bean product with enhanced
textural,
eating, and operational characteristics (e.g., speed of reconstitution).
19
CA 02490194 2004-12-15
Examples set forth below further illustrate various aspects of the present
invention:
EXAMPLE 1:
12 liters of hot water were placed in a small (8 inch diameter by 24 inch
long)
horizontal cylindrical cooking vessel. The water was then further heated to
185°F by
passing steam through the shaft of the central baffle, while slowly rotating
the baffle
so as to agitate the water.
Approximately 4000 ml of the hot water was drained from the vessel, and 7 lb.
of dry pinto beans were then placed in the vessel - one half of these beans
being
distributed along one side of the baffle, and the remaining half on the other
side of the
baffle.
The vessel was then maintained at atmospheric pressure, and the baffle was
alternately and continuously slowly rotated for one (1) minute each in the
clockwise
and counterclockwise directions. Steam was added through the baffle shaft to
maintain the bean/water mixture temperature between approximately 180°F
and
190°F. The beans immediately started to absorb the hot water, and the
rotating baffle
served to mix and contact the beans with a continuously diminishing quantity
of
water. This hydration step was continued for 20 minutes, after which
approximately
6700 ml of broth was drained from the now partially-hydrated beans. 75 grams
of salt
was then dissolved in 600 ml of the drained broth and this salt solution was
returned
to the cooking vessel.
The hatch to the cooking vessel was now secured and the vessel pressurized
with steam and held at a pressure of 10 prig for 40 minutes in order to cook
the beans.
During this cooking period, the cooking vessel baffle continued to rotate
alternatively
and slowly for one (1) minute each in the clockwise and counterclockwise
directions.
In this manner, all the beans were contacted with the remaining and
continuously
reducing broth volume.
At the end of the cooking step, the vessel was depressurized and the cooked
beans with very little remaining liquid broth were discharged into a holding
vessel.
CA 02490194 2004-12-15
These cooked beans were then chopped and texturized by a small electrically
driven meat grinder, which had a front plate with '/4 inch holes and knife
cutters which
rotated against the inner side of the front plate.
The cooked beans were manually fed into the grinder and the textured bean
mass collected as it exited through the grinder front plate.
The textured bean mass was then placed in a cylindrical vessel, and was
shaped into a sheet approximately 1 /8 inch in thickness and 4 inches wide by
applying
pressure to the vessel so as to force the bean mass through a 1 /8 inch by 4
inch slot
situated at the base of the vessel.
As the textured bean mass exited the slot, it was continuously deposited on 6-
inch by 6-inch perforated metal squares.
These perforated metal squares, supporting the wet bean sheet, were
transferred and placed on a conveyor that passes through a convective dryer.
The bean sheet was initially dried for 3 minutes and 45 seconds using
400°F
hot air impinging on the top and bottom of the bean sheet.
The partially-dried beans were then broken into smaller pieces, placed on the
perforated metal supporting squares, and finally dried for 4 minutes in the
same
convective dryer using 350°F hot air.
After cooling, these dried, textured beans were stored for rapid
reconstitution
with water, and subsequent use in food items.
EXAMPLE 2:
A dehydrated refried bean product mix was prepared according to Figure 7.
First, the "texturized composition" portion of the mix was made by placing
200 lbs. of dry raw, cleaned pinto beans in a vertical hydration vessel. The
hydration
vessel was equipped with a screen and liquid outlet so that the beans would be
immersed in hydrating liquid throughout the hydration step. 600 lbs. of hot
water
were then continuously circulated through a heat exchanger and the bed of
hydrating
beans. For the first 30 minutes of the hydration, the recirculating hot water
was
21
CA 02490194 2004-12-15
maintained at approximately 190 °F, and then the hot water was heated
to
approximately 203 °F and maintained at this temperature for an
additional 85 minutes.
The hydration vessel was then first drained of broth. The beans were very
uniformly hydrated (moisture of 61.3%) maintaining their whole-bean integrity
and
thus easily flowed out of the vessel through a 4-inch tube into a holding
container.
The hydrated beans were transferred to a cooking vessel having a 4-ft.
diameter and equipped with a central rotating baffle that extended to within
3/ ~ inch of
the cooking vessel's walls.
The cooking vessel's baffle was placed in a horizontal position and the
hydrated beans were placed on the baffle within the cooking vessel.
After eliminating the majority of the air in the cooker, the beans were then
pressure cooked by direct steam injection for about 60 minutes, the first 10
minutes at
10 psig and the remaining time at 13 psig. The central rotating baffle was
stationary
during the entire cooking step so as to maintain the whole bean integrity.
After depressurizing the cooking vessel, the condensate (which was not in
contact with the cooking beans) was first drained from the cooking vessel. The
cooked soft whole pinto beans were then removed from the cooking vessel.
These cooked beans were then fed through a series of two cutter plates (the
first having rectangular holes and the second having circular holes). In front
of each
cutter plate there was a flat 3-knived cutter rotating at approximately 150
rpm. Prior
to the first cutter plate, vegetable oil was injected into the bean stream by
a small
piston pump.
The outlet from the second cutter was connected directly to a spreader horn,
so
that the texturized composition could immediately be shaped into a flat
profile, 2-ft.
wide, with a '/a inch thick central layer having '/4 inch high by '/4 inch
thick stripped
ridges on top and bottom of the central layer (as in, e.g., Fig. 8C). This
flat profile
was continuously fed via a conveyor through a microwave/convection oven.
The conveyor moved through the oven at approximately 9 inches per minute,
and about 2500 ft.3/min. air at about 340-350°F was recirculated
through the oven.
22
CA 02490194 2004-12-15
The microwave power was set at about 42 kW and the texturized composition
exiting the dryer was dried to a moisture of between 3% - 8%. This dried
composition was then broken into small pieces of between '/4 inch and '/z inch
in size.
A second portion of beans to be used as cooked whole beans in the final
refried bean mix was prepared as follows.
Once again, 200 lbs. of dry raw beans were hydrated in a vertical hydration
vessel for a total of about 110 minutes. These hydrated beans were then
pressure
cooked for 60 minutes, by placing them on the central baffle in the cooking
vessel,
which remained stationary throughout the cooking step. In this manner, the
whole
bean integrity of the soft cooked beans could be easily maintained.
After depressurization, the cooked whole beans were continuously fed by
conveyor into a convection/microwave dryer. The beans were stacked in a layer
18
inches wide by 13/g inches high on the feed conveyor and fed through the dryer
at
about 8 inches per minute.
About 2900-3000 ft.3/min. air at 230 °F - 205 °F was
recirculated through the
dryer, while the microwave power was set at between about 55 and 57 kW.
The dried whole beans exiting the dryer were largely whole with only a small
fraction "bird mouthed".
Beans from the broken-up texturized composition and those from the "whole"
portion were dry mixed in the ratio of 70/30 and approximately 3.5% salt was
added
to the dry mix.
This dry mix, rapidly rehydrated with hot water produced a very well liked
refried bean product.
Additional drying experiments conducted in connection with the present
invention may be summarized by the following examples. It is noted that, in
all the
following experiments, cooked beans having a moisture level of either about
70% by
weight (see Examples 3-17) or about 58% by weight (see Examples 18-22) were
used
as starting material. For the latter, raw whole beans were cleaned, washed,
and then
cooked using the apparatus depicted in Figures 1-3 herein.
23
CA 02490194 2004-12-15
A batch convection/microwave oven was used in Examples 3-22. When
operating in the convection/microwave mode, the oven is set up to provide
intermittent microwave power (of approximately 0.6 kilowatts for approximately
40%
of the time). The convection system, on the other hand, circulates hot air at
a defined
temperature, and is on "continuously", in the sense that, when the microwave
mode is
"off' (and the convection mode in "on"), energy is supplied to the heating
elements of
the convection oven, and fans (or blowers) blow the hot air through and around
the
mass of beans inside the chamber. However, when the microwave mode in "on",
energy is no longer supplied to the heating elements, but the fans continue to
operate,
so that hot air inside the chamber is still forced through (and around) the
mass of
beans. Thus, during dehydration, connective heating is supplied in such a way
as to
generate and circulate hot air when microwave heating is not applied, and to
circulate
existing hot air, without generation of further connective heat, when
microwave
heating is applied.
When the convection/microwave oven is operated solely in the convection
mode, the hot air at a defined temperature is simply recirculated around and
through
the product, and no microwave energy is applied.
EXAMPLE 3:
A square microwave dish (6 in. on each side, and 1'/2 in. deep) was
used to place about 244 grams of cooked whole beans inside a combination
microwave-convection heating oven. With this setup, the beans arranged
themselves in about 2 - 2'/2 layers within the dish.
The cooked beans had a moisture level of about 70%. The beans were
first exposed to full microwave energy for a period of 3'/2 minutes (to heat
them from room temperature to 212 °F). Next, the beans were dried using
both microwave and connective energy for a period of approximately 12
minutes with the connective air temperature set at 250 °F. During this
time
interval, microwave heating was supplied intermittently, for a total of
approximately 40% of the time. In addition, the convection mode was fully
"on" when the microwave mode was "off', and only partially "on" (i.e., fans
continued to operate, so that hot air inside the oven was forced through and
24
CA 02490194 2004-12-15
around the mass of beans) when the microwave mode was "on". At the end of
this 12-minute time interval, the cooked whole bean material remaining in the
dish weighed about 120 grams.
At this time, the beans were mixed, and then dried again in the oven
for an additional period of about 8 minutes. This latter drying process was
also carried out with the same combination microwave-convective heating
procedure (with air temperature set at 250 °F) as that which was
performed for
the above-described 12-minute time period. At the end of the 8-minute time
period, a total weight of about 82 grams of dried whole bean material
remained. This included about 6 grams, or about 7.3%, of dried beans that
were visually identified as being "bird mouthed".
EXAMPLE 4:
The experiment of Example 3 was repeated, with the difference that
the drying process was carried out using convective air set at 350 °F,
rather
than at 250 °F. Starting with 236 grams of cooked beans, the beans were
first
heated solely with microwave energy for 3 '/2 minutes, and then for successive
12-minute and 8-minute periods using both microwave and convective heating
as described in Example 3. This resulted in 76 grams of dried whole bean
material, of which 14 grams, or about 18.4%, were identified as being bird
mouthed.
EXAMPLE 5:
The experiment of Example 3 was repeated, with the difference that
only about one-half as much starting material was used, such that the beans
arranged themselves in a single layer. This resulted in a shorter heating
time,
as well as about double the amount of microwave energy per unit mass of
beans. Using the same dish as in Example 3, this resulted in only one layer of
beans.
Thus, about 112 grams of beans were exposed to microwave energy for
about 3 '/2 minutes. This was then followed by an 11-minute period of both
microwave and convective heating using air set at 250 °F. The 41 grams
of
CA 02490194 2004-12-15
bean material remaining at the end of this period contained about 11 grams, or
about 27%, of dried beans identified as being bird mouthed.
EXAMPLE 6:
The experiment of Example 3 was repeated, with the difference that
only microwave energy was used to dry the beans. Thus, 254 grams of cooked
beans were exposed to full microwave power for 3 '/Z minutes, followed by a
12-minute exposure to microwave energy with the power set at 40%. The
beans were then mixed and dried for an additional 12 minutes using only
microwave energy with the power similarly set at 40%. The 84 grams of dried
bean material remaining at the end of this period contained about 13 grams, or
about 15.5%, of visually-identified bird-mouthed beans.
EXAMPLE 7:
100 grams of cooked beans were placed on a perforated rotating plate
and exposed only to convection air heating set at 350 °F for successive
15-
minute and 20-minute time periods. No microwave energy was applied.
Thirty five minutes were needed to dry the beans. At the end of 35 minutes,
all 39 grams (i.e., 100%) of the dried beans were bird-mouthed.
The following observations may be made based on the results of the
experiments summarized in Examples 3-7 above. First, when convection is used
exclusively to dry the high initial-moisture (about 70%) beans, the incidence
of bird
mouthing is higher than when either microwave energy, or a combination of
connective heating and microwave energy are used. Thus, the pure convection
experiment of Example 7 resulted in almost 100% bird mouthing, whereas the
experiments of Examples 3, 4 and 6 resulted in only about 7.3% - 18.4% bird
mouthing. In addition, dehydration using microwave and convection heating
requires
less time than when pure convection is used.
Second, as evidenced by the results of Examples 3 and 4, dehydration of the
beans using a combination of convection heating (with the air set at 250
°F) and
26
CA 02490194 2004-12-15
microwave energy results in much less bird mouthing than when the same process
is
carried out at 350 °F. As such, it is more advantageous to use lower
initial
temperatures in the "dual mode" process in order to avoid over-heating the
beans.
Third, even when the "dual mode" process is carried out at 250 °F,
increasing
the amount of microwave energy to which the beans are exposed results in a
much
larger bird-mouthing percentage due to overheating of the beans. This can be
seen by
a comparison of the results of Examples 3 and 5.
The following experiments were conducted in order to explore the significance
of the thickness of the bean layer as the beans are being dried, as well as to
compare
the use of pure microwave energy, as opposed to a combination of convection
heating
and microwave energy, to dry the beans.
EXAMPLE 8:
Similar to the experiment of Example 6, only microwave energy was
used to dry 224 grams of cooked beans in an "open" dish (i.e., 6 in. on each
side, and having no walls). With this configuration, the beans arranged
themselves into approximately 1-2 layers. After the initial 3 '/2-minute (full
microwave power) period, the beans were dried for 12 minutes, then mixed
and dried for an additional 8 minutes with the microwave power set at 40%.
Of the 72 grams of bean material remaining at the end of this period, about 23
grams, or about 32%, of the dried beans were bird-mouthed.
EXAMPLE 9:
The experiment of Example 8 was repeated, except that a large bowl
having abase diameter of 6 inches, a top diameter of 7 inches, and a depth of
4 '/Z inches was used, which resulted in 2-2 '/z bean layers. After the 23 '/2-
minute dehydration period, about 32% of the dried beans were bird-mouthed.
EXAMPLE 10:
The experiment of Example 9 was repeated (i.e., deep bowl 2-2 '/2 bean
layers), except that a combination of both microwave energy and convection
heating with the air temperature set at 250 °F was used to dry the
beans. After
27
CA 02490194 2004-12-15
23 %z minutes (3 '/z + 12 + 8 minutes), the dried beans exhibited a bird-
mouthed rate of about 25%.
EXAMPLE 11:
The experiment of Example 8 was repeated (i.e., open dish, 1-2 layers),
except that the beans were dried using a combination of convection heating
(with the air set at 250 °F) and microwave energy. With the beans again
arranging themselves in about I-2 layers, after 23 '/z minutes (3 '/z + 12 + 8
minutes) and drying at about 250 °F, the dried beans exhibited a bird-
mouthed
rate of about 33%.
EXAMPLE 12:
Beans were placed in a small bowl (about 4 '/z inches in diameter and 3
'/z inches deep), where they arranged themselves in 4-5 layers. The beans
were dried using a combination of both convection heating (with the air set at
250 °F) and microwave energy. After 23 '/z minutes (3 '/z + 12 + 8
minutes),
the dried beans exhibited a bird-mouthed rate of about 11 %. This experiment
was repeated a second time, with a bird-mouthed rate of about 8%.
EXAMPLE 13:
The experiment of example 12 was repeated, except that only
microwave energy (at 40% power level) was applied. After 23 '/z minutes (3
'/z + 12 + 8 minutes), the dried beans exhibited a bird-mouthed rate of about
10%.
EXAMPLE 14:
In order to assess the impact of drying under high humidity conditions,
a large container having a diameter of 8 '/2 inches, a depth of 1 '/z inches,
and a
lid having 8 transverse 1/8-inch holes was used to dry beans with microwave
energy only. Beans were placed in the container and the lid used to cover the
container. The beans, which arranged themselves in only 1 layer, were first
dried for 3'/z minutes at full power, followed by a 12-minute period with the
microwave at about 40%. The beans were then mixed and dried for an
28
CA 02490194 2004-12-15
additional 11 minutes using the microwave at about 40%. The dried beans
exhibited about 14% bird mouthing.
EXAMPLE 15:
The experiment of Example 14 was repeated with the lid removed. At
the end of 26 '/2 minutes, the dried beans exhibited about 30% bird mouthing.
EXAMPLE 16:
A flat bowl (6 inches on each side, and 13/4 inches deep) was used to
place about 230 grams of cooked whole beans inside a combination
microwave-convection heating oven. With this setup, the beans arranged
themselves in about 2-2'/Z layers within the bowl.
The beans were first exposed to full microwave power for a period of
3'/z minutes. Next, the beans were dried for a period of approximately 12
minutes using both microwave energy (with power set at 40%) and convective
heating (with the air temperature set at 250 °F). The beans were then
mixed
and dried for an additional 8-minute period. Of the remaining 63 grams of
bean material about 9 grams, or about 14.3%, of the beans exhibited bird
mouthing.
EXAMPLE 17:
The experiment of Example 16 was repeated, with the difference that
only microwave energy was used to dry the beans. After 23 '/2 minutes (3 '/2 +
12 + 8 minutes), the dried beans exhibited a bird-mouthed rate of about 27%.
The following observations may be made based on the results of the
experiments summarized in Examples 8-17 above. First, when the beans are
arranged
in about 1-2 layers, dehydration with pure microwave energy as opposed to a
combination of convective heating and microwave energy yields similar results.
Thus, in Examples 8 and 11, 32% and 33%, respectively, of the beans were bird-
mouthed.
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CA 02490194 2004-12-15
Second, with 4-5 bean layers, dehydration with either pure microwave energy
or a combination of convective heating and microwave energy yields very
attractive
results. Thus, Examples 12 and 13 indicate that, with multiple layers,
especially in
the range of 4-5 layers, a bird-mouthed rate of 8%-11% may be achieved.
Third, when the beans are arranged in 2-2 '/2 layers in such a way that the
effect of convection heating is either minimized or eliminated, dehydration
using
either pure microwave energy or a combination of convective heating and
microwave
energy yields similarly high bird-mouthed rates. Thus, in Examples 9 and 10,
the
relatively deep bowl in which the beans were dried nullifies the effect of
convection
heating, such that bird mouthing in the range of 25% - 32% is observed.
Fourth, when the beans are arranged in 2-2 '/2 layers, and the effect of
convection heating is not minimized or eliminated, dehydration with a
combination of
convective heating and microwave energy yields more advantageous results than
dehydration with pure microwave energy. Thus, the experiment of Example 16
resulted in a bird-mouth rate (14.3%) that was about half as much as that
achieved in
the experiment of Example 17 (i.e., about 27%).
Finally, when the beans are arranged in a single layer, as in Examples 14 and
15, dehydration of the beans in the presence of a higher amount of humidity
provides
better results. Thus, in the experiment of Example 14, a 14% bird-mouthing
rate was
achieved, compared to about 30% in the experiment of Example 15.
For purposes of comparison with the results of the above experiments, the
following experiments were carried out using beans having a lower initial
moisture
content of about 58% that were cooked using the apparatus depicted in Figures
1-3
herein:
EXAMPLE 18:
A flat dish (6 in. on each side, and having no walls) was used to place
about 188 grams of cooked whole beans inside a combination microwave-
convection heating oven. With this setup, the beans arranged themselves in
about 1-2 layers within the dish.
CA 02490194 2004-12-15
The beans were first exposed to full microwave energy for a period of
3'/2 minutes. Next, the beans were dried for a period of approximately 12
minutes using both microwave and convective heating with the circulating air
temperature set at 250 °F. During this time interval, microwave heating
was
supplied intermittently, for a total of approximately 40% of the time. In
addition, the convection mode was fully "on" when the microwave mode was
"off', and only partially "on" (i.e., fans continued to operate, so that hot
air
inside the oven was forced through and around the mass of beans) when the
microwave mode was "on". At the end of this 12-minute time interval, the
cooked whole bean material remaining in the dish weighed about 82 grams.
At this time, the beans were mixed, and then heated again in the oven
for an additional period of about 3 minutes. This latter heating process was
also carried out using circulating air temperature set at 250 °F, with
the same
combination microwave-convective heating procedure as that which was
performed for the above-described 12-minute time period. At the end of the 3-
minute time period, a total weight of about 77 grams of cooked whole bean
material remained. This included about 8 grams, or about 10%, of the dried
beans exhibiting a bird mouthed effect.
EXAMPLE 19:
The experiment of Example 18 was repeated, with the difference that
the successive 12- and 3-minute drying stages were carried out using
circulating air temperature set at 225 °F rather than at 250 °F.
The dried beans
exhibited a bird-mouthed rate of about 9%.
EXAMPLE 20:
190 grams of cooked whole beans were placed on a flat dish (6 in. on
each side, and having no walls), such that the beans arranged themselves in
about 1-2 layers within the dish. The beans were exposed only to microwave
energy at full power for an initial period of 3'/2 minutes, followed by 12
minutes of microwave energy at about 40% power (as explained above). The
beans were then dried for an additional period of 4 minutes, again using
solely
31
CA 02490194 2004-12-15
microwave energy at about 40% power. At the end of the 19 '/2-minute
process, the dried beans exhibited a bird-mouthing rate of about 16%.
EXAMPLE 21:
188 grams of beans were placed in a large container having a diameter
of 8 '/z inches and a depth of 1 '/z inches, and the container was closed with
a
lid having 8 transverse 1/8-inch holes. The beans, which arranged themselves
in only 1 layer, were dried using microwave energy only. The beans were first
dried for 3'/z minutes at full microwave power, followed by a 12-minute period
with the microwave at about 40%. The beans were then dried for an
additional period of 4 minutes, again using solely microwave energy at about
40% power. At the end of the 19 '/2-minute process, the dried beans exhibited
a bird-mouthing rate of about 5%.
EXAMPLE 22:
188 grams of beans were placed in a small bowl (about 4 '/2 inches in
diameter and 3 '/2 inches depth), where they arranged themselves in 4-5
layers.
Using microwave energy only, as in Examples 20 and 21, the beans were first
dried for 3'/2 minutes, followed by a 12-minute period with the microwave at
about 40%. At the end of the 15 '/2-minute process, the dried beans exhibited
almost no bird-mouthing at all.
The following observations may be made based on the results of the
experiments summarized in Examples 18-22 above. First, dehydration of cooked
beans having a higher initial moisture content results in a higher rate of
bird mouthing
in the dried bean product. Thus, for instance, the experiments of Examples 8
and 11,
in which beans having an initial moisture content of about 70% were used,
yielded
bird-mouthing rates of about 32-33%. In contrast, the experiments of Examples
18
and 20, in which beans having an initial moisture content of about 58% were
used,
yielded bird-mouthing rates of about 10-16%.
Second, with multiple bean layers, and in particular, with 4-5 bean layers,
bird
mouthing of the beans can be essentially eliminated. See, e.g., Example 22. In
addition, as evidenced by the results of the experiment of Example 22,
dehydration of
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CA 02490194 2004-12-15
the beans can be achieved in a shorter amount of time than would be possible
with
either pure convection heating or drying with 1-2 bean layers. In this regard,
the
experiment of Example 20, for instance, in which the beans arranged themselves
in 1-
2 layers, required 19'/z minutes to dry the beans using microwave energy. In
contrast,
the experiment of Example 22 required only about 151/z minutes to accomplish
the
same task.
Third, as shown by a comparison of the results of the experiments of
Examples 20, 21, and 22, the incidence of bird mouthing can also be reduced by
drying the beans in a higher-humidity environment. Thus, the experiment of
Example
21 resulted in only about 5% of the beans exhibiting bird mouthing, as opposed
to
about 16% in the experiment of Example 20. In addition, this reduction in bird
mouthing can be achieved in a shorter amount of time (i.e., in this case, 19%z
minutes)
than would be possible with pure convection heating. Nevertheless, the higher-
humidity dehydration process summarized in Example 21 is still slower than the
larger-bean-layer dehydration process summarized in Example 22. Thus, it
appears
that, although either higher humidity conditions or larger bean layers may be
used to
decrease bird-mouthing rates, the dehydration process is faster when multiple
bean
layers are used.
Finally, with 1-2 layers of beans, dehydration using a combination of
convective heating and microwave energy appears to be a slightly faster
process than
dehydration using pure microwave energy. Thus, the experiment of Example 18
took
about 18 '/z minutes to complete and resulted in a bird-mouthing rate of about
10%.
The experiment of Example 20, on the other hand, took about 19 '/z minutes to
complete and resulted in a bird-mouthing rate of about 16%.
In this regard, and for purposes of comparison, beans fiom both moisture
categories, i.e., those having an initial moisture content of about 58% (that
were
cooked using the apparatus depicted in Figures 1-3 herein) and those having an
initial
moisture content of about 70% were separately dried in a continuous
impingement
convection oven (e.g., Lincoln impingement oven) using convection only. In
both
cases, the beans were placed on a teflonized perforated plate (l2in. x 12
in.), where
they arranged themselves in about 1 - 1 '/z layers. The beans were then dried
for just
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CA 02490194 2004-12-15
over 10 minutes at 235 °F, followed by 8 %Z minutes at 265 °F,
and 9 '/4 minutes at 300
°F. Thus, the total drying time was about 28 minutes.
In several experiments carried out according to the above conditions, at the
end of the 28-minute period, the lower-moisture-content beans exhibited a bird-
s mouthing rate in the 21 % - 24% range. In contrast, the beans having a
higher
moisture content exhibited almost 100% bird mouthing. Comparison of these
results
with those of the above-described Examples indicates that, while drying the
lower-
moisture-content beans using solely convective heating may result in slightly
higher
drying times, it does, nevertheless, allow for bird-mouthing rates that are
below 25%,
i.e., where a substantial fraction of the dried whole beans preserve their
structural
integrity.
All in all, the above experiments point to an extremely attractive, and
surprising, result: dehydration of beans in larger layers using either pure
microwave
energy or a combination of convective heating and microwave energy provides
not
only lower bird-mouthing rates, but also higher throughput. Thus, embodiments
of
the present invention provide for an industrial solution whereby more beans
can be
produced in a shorter amount of time, with a substantial fraction of the beans
retaining
their structural integrity.
In this regard, embodiments of the invention may employ a heating chamber
allowing continuous product passage therethrough, rather than a traditional
convection/microwave oven. Thus, for example, a heating chamber capable of
providing convective heating and/or microwave energy may be equipped with a
conveyor or other similar means for continuously advancing the beans through
the
chamber. In this configuration, the speed of the conveyor will be determined
by the
number of bean layers, the exposure temperature, the required duration of
exposure,
the level of humidity within the chamber, etc.
Embodiments of the present invention are also directed to a method of
producing a reconstitutable dehydrated chunky bean product so as to
substantially
eliminate hard beans from the bean product, wherein dried whole beans produced
by
the methods described immediately above so as to be substantially free of bird-
mouthing effects can be added at various points within the process outlined in
Figure
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CA 02490194 2004-12-15
6. In this way, a reconstitutable dehydrated bean product may be produced that
has an
improved amount of chunkiness and home-made feel due to the existence of
actual,
structurally intact, whole beans in the final, reconstituted product. In
addition, as
shown in Figure 7 for illustrative purposes, additives such as salt, colorant,
flavor
ingredients, and/or oil may be added to either portion of beans at various
points (e.g.,
prior to cooking, prior to chopping, etc.).
It will be apparent to a person of ordinary skill in the art that embodiments
of
the present invention are not limited in their design or application to
specific
embodiments disclosed herein. For example, injection of steam into the
stationary
pressure vessel may be accomplished through ports in the vessel walls. In
addition,
while the steps of embodiments of the methodology lend themselves to dried
legumes,
other food-stuffs (e.g., carrots, celery, meats, chicken, fish and the like)
are also
within the scope of the present invention. Thus, the present invention is
intended to
encompass all of the embodiments disclosed and suggested herein as defined by
the
claims appended hereto and any equivalents thereof.
