Note: Descriptions are shown in the official language in which they were submitted.
r~
PROCESS FOR MAKING SHREDDED CEREALS AND
PRODUCTS OBTAINED THEREBY
8ACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the production of ready-to-eat
shredded cereal products and to shredded cereal products.
2. De cription of the Prior Art
Several processes are known for the production of
ready-to-eat breakfast cereals which are in shredded form.
Tempering of the cooked grains prior to shredding has be~n
considered necessary for obtaining strong continuous shreds. In
U.5. Patents l~548,086 and 1,159,045, cooked wheat or similar
grains are subjected to tempering times of over 12 hours before
shredding. As described in U.S. Patent 4,179,527, in the
manufacture of a whole wheat food product such as shredded wheat,
whole wheat is cooked sufficiently to gelatinize the starch.
Gelatinization is a function of water penetration into the
whole berry, temperature, and time, for a given type of grain.
According to U.S. Patent 4,179,527, the gelatinization of wheat
starch involves a destruction of bonds in the crystalline regions
of starch granules. Retrogradation is the return of the starch
molecules to a crystalline structure, which is different from the
original crystalline structure, upon cooling. Tempering permits
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~ ~LZO~1967
the gelatinized wheat starch to slowly cool and permits water
migration through the wheat particles to achieve a uniform water
distribution within the particles. Retrogradation occurs during
tempering. As reported in U.S. Patent 4,179,527, if shredding is
attempted shortly after cooking, the insufficient degree of
retrogradation or tempering results in at best, short
non-continuous strands and/or strands which are tough, curly, or
suffer from other physical or textural disadvantage. In U.S.
Paten~ 4,179,527, the time required for the tempering of cooked
whole wheat is substantially reduced by chilling the wheat at a
temperature o from 1C to about 12C.
Processes wherein tempering is not specifically mentioned or
is indicated as belng optional in the production of cereals from
wheat or other grains, are disclosed in U.S. Patents 1,189,130,
1,210,589, 2,008,024, 1,946,803, and 502,378. In U.S. Patent
1,189,130, bran, such as wheat bran, is mixed with up to 50% of
whole wheat or other gelatinous cereal flour, and is cooked in
pans in a steam retort. The cooked product is dried ~o form
lumps and the lumps are then fed through shredding mills. In
U.S. Patent 1,210,589, a composite cereal product is formed by
mixing bran, shredded wheat, and syrup, moIding the mixture and
then baking it. In U.S. Patent 2,008,024, a cereal biscuit is
prepared by steaming or boiling wheat~ surface drying the cooked
product, and then converting it into a thin ribbed sheet. The
shredding rolls are spaced sufficiently apart so that a sheeted
material with ribs is obtained instead of a shredded product. Tn
U.S. Patent 1,946,803, rice, alone or in combination with bran,
is s~eam cooked, dried and cooled to a rubbery consistency and
~z~æ~967
optionally held for tempering to effect a uniform water
distribution. This product is ~hen passed between grooved
rollers to form long flat ribbons. These rlbbons are dried to
produce a brittle product which is broken and then puffed by
toasting. In U.S. Patent 502,37~, a cereal grain is prepared for
shredding by boiling, steaming/ steeping or soaking. Depending
upon the spacing between the rollers, a product in the f orm o f
threads, lace, or ribbons, or sheets, and the like, is obtained.
Processes for the production of shredded oat cereals wherein
considerable tempering is used, as in the conventional process
f or the production o~ shredded wheat, are disclosed in U.~.
Patents 1,170,162, 1,197,297, and 4,004,035. Tempering of cooked
oa~s is also disclosed in U.S. Patent 3,733,206. However, in the
process of the latter patent, the biscuits contain flaked
compacted cereal grains as opposed to shreds. In U.S. Patent
1,170,162 and in U.S. Patent 1,197,297, the whole berry is
pulverized so as to permit flavoring ingredients to be
incorporated in the final product. A dough is formed from flour,
flavoring, and water. The dough is then-cooked, rolled into
slabs and then atmospherically dried for a period of 24 to 40
hours. The dried product is toasted, broken into pea size pieces
and then shredded. In U.S. Patent 4,004,035, it is disclosed
that during the`continuous production of shredded biscuits using
a press type cutter or ~otating contact cutter, to sever the web
across the shreds~ the tensile strength and stickiness of the
shredded material limits the ability of these cutting devices to
perform satisfactorily. The shredded material, it is disclosed,
tends to adhere to the blade or the blade will not completely
Si9Çi7~
sever it. In U.S. Pa~ent 4,004,035, the shredded biscuits are
formed by depositing a layer of shredded cereal in zig-zag
configuration on a moving bel~ and then severing the material.
However, tempering for a considerable amount of time as in these
processes, is undesirable from the standpoint of equipment costs,
plant efficiency, and excessive microbial growth. Furthermore,
it has been found that when cooked whole oat groats are tempered
prior to shredding, shreddability decreases. The deleterious
effect of long tempering times upon the shreddability of oats is
unexpected in view of the art~taught need to temper wheat to
enable its shredding.
Processes for the production of cereal products made from
oats without any apparent tempering step, are disclosed in U.S.
Patents 897,181, 3,062,657, 3,462,277, 3,732,109, and Canadian
Patent 674rO46. In U.S. Paten~ 897,181, the oats are wetted but
not cooked and then passed repeatedly be~ween grooved rollers and
then baked. The boiling or steaming of th~ grain, it lS
disclosed, produces considerable change in the chemical quality
of the grain an~ a number of the nutritious soluble elements
escapes from the grain to the water. In the processes of the
remaining patents, a shredded product is not produced by means of
shredding rollsO In U.S. Patent 3,062,657, ~lour and water are
mixed to form a dough in an extruder. The dough is cooked in the
extruder and then tempered in the extruder at a lower
temperature. The extrudates are cut into pellets to simulate
cooked and dried grains such as corn grits, whole wheat berries,
oa~ groats, rice and the like. The extrudates, it is disclosed,
have a moisture content ideal for flaking. It is generally on
the order of 18 to 24% by weight, the moisture being uniformly
distributed throughout so that the necessity for tempering is
entirely eliminated and the extrudate can be immediately
transferred to a flaking operation. It is disclosed that it is
preferable to further cool the extrudate before it enters the
flaking device to optimize flaking properties.
In U.S. Patent 3,462,277, a mixture of flour and water is
passed through an extruder to gelatinize the starch while the
dough is cooked and transformed into a rubber-like mass. The
moisture content of the mixture is 13 to 35%. The continuous
U-shaped extrudate is pinched off into segments by cutting rolls
to form canoe-shaped cereal products. The separated canoe-shaped
pieces are then dried to below 15% moisture.
U.S. Patent 3,732,109, discloses the production of a
ready-to-eat oat cereal biscuit by subjecting an oat flour-water
mixture to a water boiling temperature and superatmospheric
pressure to gelatinize a portion of the starch in the oat flour.
The mixture then passes through an orifice and the extruded
product is cut into small pieces. The flake-shaped pieces which
are formed are dried to a moisture content of from about 2~ to
about 6% by weight water. The dried flakes are then subdivided,
admixed with a syrup, and compacted into the form of a biscuit.
The formed biscuits are then dried to a moisture content of from
about 4 to 5% by weight.
In Canadian Patent 674,046, a shredded dry oat cereal
product is produced without the use of shredding rolls. A dough
is cooked in a screw extruder, extruded through orifices to form
a strand bundle, and the strand bundle is cut into pieces by a
gl2~ 7
cutting device which may be a pair of rolls.
In the production of a shredded oat cereal by means o
shredding rolls, obtaining the cooked oats in a form which
will produce continuous shreds is only one of several problems
which are encountered. When oats are cooked atmospherically in
water, an oatmeal-type product is obtained which sticks
excessively to material handling equipment, such as conveyor
belts and hoppers, as well as to the shredding rolls. Drying of
the cooked product prior to shredding does not so]ve this
problem. Stickiness is experienced upon transport to the dryer.
Moreover, when water cooking is limited in time to reduce
stickiness, shreds produced from the oats contain white streaks.
Oat groats, as well as oat flour, contain oat gum. The gum,
as reported by Shukla, T., "Chemistry o~ Oats: Protein Foods and
Other Industrial Products", Critical Reviews in Foods Science and
Nutrition, pps. 383~424 (Oc~ober 1975), is soluble in water at
ambient temperature and is believed to be responsible for the
gelatinous property of oatmeal. The cooking of oat groats
atmospherically in water results in excessive extraction of the
gums from the interior of the oat groat to the surface. The
presence of the oat gums at the surace impedes ~he penetration
of water into the oat groat for gelatiniza-tion of the oat starch.
Additionally, white streaks are also produced by overcooking
the oat groats. It is believed that overcooking either results
in bursting of the starch granules to expose white materials or
results in a reaction product which is white. It has also been
found that pressure cooking the oat groats with steam so as to
provide a moisture content in the cooked groats which is
6~
sufficiently high to obtain a shreddable product also results in
the development of white streaks.
Cooking to eliminate white centers in grains is taugh~ in
U.S. Patent 2,421,216. Particles of cereal grains such as corn~
rye, wheat, bran, rice, or oat groats are composited with
particles of de-fatted soya beans in the form of grits, flakes,
or meal to enhance the protein content of the cereal by use of a
two-stage pressure cooking step.
The cereal grain is first cooked with ~lavoring solution in
a rotary steam cooker. The cooker is maintained at from about 15
to about 20 lbs. steam pressure. Means are provided for the
admission and discharge of steam, so as to permit the cooking to
be carried out at a temperature of from about 250~F to about
260F. The flavoring solution is an aqueous solution containing
about 8% sugar, 3.5% salt, and a small percentage of malt
extract. The amount of the flavoring solution which is added to
the cereal grain particles is in proportion to the original
moisture content of the cereal grain. It is added in an amount
so that the amount of moisture in the particles on leaving the
cooker is from about 30 to about 45%~ The de-fatted soya is
separately tempered with about one part by weight of flavoring
solution to about 3 parts by weight of de-~atted soya bean
particles so that all of the solution becomes absorbed by the
de-fatted soya bean particles. The cooking of the cereal is
interrupted for the addition o~ the tempered soya. The cereal
and the tempered soya are then cooked under substantially the
same conditions of steam pressure to which the cereal was
subjected during the initial cooking period.
67
The total cooking period to which the cereal component is
subjected to should, according to U.S. Patent 2,421,216, be such
that the starches are hydrolyzed and highly dextrinized and the
particles superficially gelatinized with no free starch or white
center. The cereal particles, it is taught, should also have a
light adhesive action on the intermediately added soya bean
particles. The mixed mass of cereal and soya which is removed
from the cooker, has a moisture content from about 30 to about
45%. This mass is then dried to a moisture content of from about
24 to about 32% using air at about 130F. The dried mass is then
tempered for about 15 to 30 minutes before shredding in a
shredding mill wherein the particles of soya become substantially
uniformly spread out over and mixed with the cereal particles and
adhered thereto by pressure through the shredding rolls. The
shredded product is cut on a rotary cutter, dried on a rotary
drier to about 20 to 28~ moisture, dried in an oven to about 7 to
15~ moisture content, and toasted to a moisture content of about
2.5%-. From about 15% to as high as about 40~ of de-fatted soya
bean par~icles, based upon the weight of soya bean and cereal is
used.
According to U.S. Patent 2,421,216, the soya must be
de-fatted 30 as to permit proper proce~sing or good shredding in
the mills. The de-fatted soya, which adheres to particles of the
cereal, is believed to provide strength to the shredded product
thereby enabling continuous ~hredding. In the case of oat
groats~ in Example V, the oat groats are first tempered, steamed
and bumped or deformed pcior to cooking them in the pressure
cooker. This pretreatment would increase surface stickiness,
:~208~
which is desired for adhesion of the soya particles to the oat
particles. It is believed that the soya particles, in adhering
to the particles of cereal, tie up the sticky gums and starches
on the cereal thereby reducing adhesion of the cereal particles
to the material handling equipment.
The two-stage cookina o cereal grains is also disclosed in
U.S. Patents 3,512,990 and 3,787,584. In the process of the
former patent, the dough, made from farinaceous materials such as
wheat, corn, oats, rice potatoes, or legum~s, is optionally
par~ially or completely cooked with added moisture, to an
approximate moisture content of about 30%. After this cooking
step, the mixture is rendered homogeneous by passing it through
an extruder, for example. The extruded product is dried to an
approximate moisture content of 22 to 24~. The dried dough is
then compacted between two rolls to provide a shredding effect
and produce a sheet of dough having diamond-like regularly spaced
perforations. The sheet of dough is then se~ered into strips,
folded to ~orm small biscuits which are closed on three sides and
then deep fried.
In U.S. Patent 3,787,584 an emulsifier free instant-tyQe
corn grits food product is produced by heating a mixture of corn
grits, water and polysaccharide gum in a critical temperature
range for a critical time period. The heated mlxture is then
heated in a second heating step which consists o~ a critical
temperature range. The mixture is dried as a thin sheet on a
drum dryer and then the cooked, drled sheet is comminuted. The
first heating step is conducted at a temperature of rom 60C to
80C so that the starch does not "set" or does not substantial~y
67
gelatinize. In the second heating step, the mixture is heated to
a temperature of from 90C to 100C. The heated mixture is dried
within 2 minutes oE the t.Lme that the second heating step i~
accomplished. Polysaccharlde gums, it is disclosed, are also
used in the production of instant oatmeal.
In U.S. Patents 9~7,088, 1,019,831, and 1,021,473, corn or
another grain is ground and immersed in an amount of water which
is limited to that which will be taken up by the grain during
cooking. The purpose of this is to preserve in the cooked
article the aroma and other properties of the grain which might
otherwise be carried off or dissipated by the evolution of steam
or vapor. In these processes, the cooked dough is extruded
through a perforated plate to obtain filaments. However, in the
production of a shredded oat product, if the moisture content of
the oats is too low, either because of cooking in an insufficient
amount of water or because of drying after the cooking step,
consistent production of continuous shreds on shredding rolls
canno~ be achieved.
The present invention provides a process for the production
of ready-to-eat shredded oat cereals made from whole groat oa~s
alone or in combination with other cereal grains which have the
shredded appearance and texture of shredded whole wheat. The
cooked and cooled oats are in the ~orm Oe discrete, individual or
non-interconnected particles, which have good flowabillty through
material handling equipment, do not exhibit a "tunnel.ing effect"
when flowing through hoppers, are readily ~hreddable into strong
continuous shreds on a consistent basis using shredding rolls,
and the baked product is free o white streaks or white spots,
~2~ 67
The process can be conducted continuously without a tempering
step which reduces operating and equipment costs. Additionally,
material handling equipment, shre~ding equipment, and baking
equipment conventionally used in the production of shredded wheat
can be used in the process of the present invention.
Accordingly, existing plants for the production of shredded whole
wheat can readily be adapted to the production of shredded oats
without substantial equipment modification.
SUMMARY OF THE INVENTION
The present invention relates to a process for the
production of shredded oat food products, such as ready-to-eat
breakfast cereals having the shredded appearance and texture of
shredded whole wheat. White streaks or spots in the final
product, which result from uncooked grain or overcooked grain,
are-eliminated by pressure cooking the oats in at least two
stages, the amount of water used in the first pressure cooking
stage being limited to partially gelatinize the starch without
substantial extraction of water soluble starches and gums -to the
surface of the oat particles. The amount Oe water used in the
remaining pressure cooking stage or stages should be sufficient
to eliminate at least substantially all of the white portions in
the oat particles and to provide a water content in the oat
particles which is sueficiently high to enable continuous
shredding on shredding roller3. Additionally, the amount of
water in each of the remaining stages should be limited to avoid
11
~2~J8~i7
substantial extraction of the gums and water soluble starches to
the surface of the partially cooked oat particle.
The multi-stage pressure cooking step is eollowed by a
cooling step which stops further cooking, partially dehydrates
the cooked grain, and produces a non-sticky surface on the cooked
grain. The non-sticky surface permits movement of the cooked,
non-interconnected oat particles through material handling
equipment such as screw conveyors, flow tubes and hoppers. No
tempering of the cooked oats is required before shredding.
Accordingly, the process can be carried out in a continuous
manner without the need for multiple tempering vessels. The
cooled, surface-dried product is shredded using shredding rolls,
and baked in conventional equipment used for the production of
shredded whole wheat. Whole oat groats are the preferred form of
oat particles for use in the multi-stage pressure cooking step of
the present invention. Shredded cereals made from mixtures of
oats with other grains, can be made in the process of the present
invention by admixing the cooled, sur~ace dried oats with at
least one other cooked, shreddable grain prior to shredding.
DETAILED DESCRIPTION OF THE INVENTION
The process for producing the shredded oat food products of
the present invention comprises subjecting oat particles to a
pressure cooking step in at least two stages to eliminate at
least substantially all of the whiteness of the oat particles,
cooling and surface drying the cooked oat particles to obtain
12
i
1208967
discrete, individual or non-interconnected free-flowing oat
particles, shredding the surface-dried oats, forming the shredded
product into pieces, such as biscuits, and baking the pieces.
The oat particles (also referred to as oats) which are
subjected to the multi-stage cooking step of the present
invention are preferably whole oat groats. Commercialy available
whole oat groats, either steamed or unsteamed, can be used.
Steamed oats are preferred because the steaming reduces enzymatic
activity which increases storage life of the raw material.
~umping of whole oat groats tends to increase extraction of gums
and starches during cooking which increase stickiness and is,
therefore, not desirable. Commercially available steel cut or
fine ground oats are not desirable because they tend to become
too sticky upon cooking. Other oat products in pellet form,
approximately the size of uncooked oat groats, such as pelletized
ground or steel cut oats however, are suitable. Pelletization
can be accomplished on conventional pelletizing equipment.
However, pelletization adds steps, making pellets more costly to
use, than whole oat groats.
~0 The amount of water used in each pressure cooking stage, and
the duration and temperature of the cooking should provide for
sufficient migration of the water into the oat particles to
gelatinize it. However, these parameters should be limited so as
to prevent substantial outward migration or extraction of the
water soluble starches and gums. Higher amounts of water are
used in the second and any subsequent pressure cooking stages, ~o
eliminate whiteness in the oat particles. Howe~er, substantial
extraction or miqration of the water soluble starches and gums is
13
'I
~;7
still avoided in the second and subsequent s~ages. It is
believed that in the first stage, gelatinization occurs
predominantly in the outer layer Oe the oat particle. This
gelatinized outer layer then presents a greater barrier to
outward migration of the gums and water soluble starches than to
the inward migration of water for further gelatinization of
starch in the inner layers.
In the first stage of the cooking step, ~he oats are
pressure cooked to achieve a moisture content in the oat
particles generally in the range of about 15~ to about 25~ by
weight, preferably about 20% by weight, based upon the weight of
the oat particles at the end of the cooking stage. Thus, the~e
weight percent ranges take into account the initial moisture
content of the oat particles and the amount of water which is
absorbed or which migrates into the oat particles during the
cooking. Commercially available whole oat groats typically have
a moisture content of about 10 tv 12% by weight. The amount of
water which is added to the first stage cooker, for cooking the
oat particles is limited so as to achieve the above moisture
content range of about 15 to 25% by weight, preEerably about 20~
by weight, assuming that all of the water which is added is
absorbed by the oat particles. Generally, most of the water is
supplied to the cooker as hot water. The remaining portion Oe
this water, typically less than about 53 by weight, is produced
by condensation of some of the steam supplied to the cooker. If
larger amounts of water are used, the gums tend to be excessively
extracted to the surface and apparently prevent sufficient water
transfer to the center of the oats to enable cooking of the
1~
~o~
interior portions oE the oat particles.
The steam pressure in the first stage cooking should
typically be between about 10 p.s.i.g. to about 25 p.s.i.g.,
preferably from about 15 p.s.i.g~ to about Z0 p.s.i.g. The steam
supplied to the irst stage cooking can be superheated or almost
saturated so as to minimize steam condensation which results in
better control over the weight percentage of water used for
cooking the oat particles. The temperature within the cooker
during the first stage cooking should range from about 240F to
about 260F, preferably from about 250F to about 260F. At
; temperatures above about 260F the oats tend to become too mushy
and sticky, and tend to produce poor quality shreds. At
temperatures below about 240F the oats are drier but white spots
and weaker shreds tend to result. The cooking time in the first
stage should range from about 10 minutes to about 25 minutes,
preferably from about 15 minutes to about 20 minutes. If shortec
cooking times are used, shred strength deteriorates. Longer
cooking ti~es further extract the gums, and excessive stickiness,
a decrease in the flowability of the cooked oats and white spots
in the cooked product tend to result. In the first stage
pressure cooking, approximately 15% to about 33% by weight of the
starch, more preferably about 17% to about 25% by weight of the
starch, is gelatinized at the end of the first stage. Further
gelatinization in this stage tends to result in weaker shreds.
The weight percent of the starch which is gelatinized, or
the degree of gelatinizatlon, is determined spectrophoto-
metrically. First, the gelatinized starch is measured, then the
total starch is measured. The procedure is:
~2~967
A. Gelatinized Starch: 2.00 g of cooked oa~s are shredded
on a shredding roll and then blended with 95 ml H20 and 5
ml of 1~ NaOH in an Gsterizer jar at high speed for three
minutes. The blend is then transferred to a 200 ml
volumetric flask and water is added to the 200 ml mark.
The mixture is then centrifuged at 3000 rpm for 10
minutes. A 2 ml aliqUQt of supernatant li~uid is then
pipetted into a beaker containing 15 ml of water and 0.45
ml of lN NaOH. The pH is adjusted to 7.0 ~ 0.5 by
dropwise addition of 0.1 N HCl or 0.1 N NaOH as needed.
The resulting solution is then transferred to a 100 ml
volumetric flask, followed by addition oE 1 ml of iodine
reagent. The iodine reagent contains one part of iodine
(I2) per four parts of KI by weight. Addition of the
iodine reagent turns the solution blue. Water is added
to the solution to bring the volume up to the 100 ml
mark. After five minutes, the absorbance of the solution
at 600 nm is mea~ured on a spectrophotometer.
B. Total Starch: Another 2.00 g of the cooked oats are
shredded on a shredding roll and then blended with 50 ml
of boiling water at high speed for three minutes. The
blend is then cooled to room temperature. Then 50 ml lN
NaOH are added to the cooled blend followed by gentle
mixing for five minutes. The mixture is transferred to a
200 ml volumetric flask and diluted with water up to the
200 ml mark. The mixture is centrifuged and further
treated as in Step A except that the 0.45 ml NaOH is not
added.
16
~1,2~1S96~7
The degree of gelatinization is the absorbance measured in Step A
divided by the absorbance measured in Step 3 times 100.
In the second cooking staye, the weight percentage Oe water
is greater than the weight yercentage of water used in the first
cooking stage. Having accomplished the conversion o~ a
significant portion of the white in~erior of oat groats, for
example, to a light tan color in the first stage, further
gelatinization of the starch is accomplished in the second stage
to eliminate at least substantially all of the white portions in
the oat particles. At the end of the second stage approximately
37~ to 50~ by weight of the starch is generally gelatinized.
Higher degrees of gelatinization here also tends to result in
weaker shreds.
The amount of water added in the second stage should b4
limited so as to achieve a moisture content of about 40% by
; weight to about 50% ~y weight, based upon the weight of the oat
particles at the end of the second stage cooking step, assuming
that-all of the water which is added is absorbed or migrates into
the oat particles. Generally, most of the added water is added
as hot water. The rema-ining portion of this water, typically
less than about 5~ by weight, is produced by condensation of some
of the steam supplied to the cooker. If larger amounts of water
are used, then the exterior of the oats tend to become
excessively sticky thereby hampering subsequent transport of the
cooked oats to and through the shredding equipment.
In each cooking stage the temperature of the water which is
added should preferably be relatively high so as to reduce
heat-up time and to avoid excessive cooling Oe the oats. Prior
17
67
to the start of any cooking, the water which is added can be at
about 50F to about 170F, ~or example. Water temperatures of
about 150F to about 190F are suitable in subsequent cooking
steps. Water addition should be done as quickly as possible to
avoid excessive extraction of water soluble s~arches and gums
which tends to occur under atmospheric conditions. It is
preferable to add all of the water in a subsequent cooking stage
within abo~t 3 minutes. This can be accomplished by means of a
pump, preferably without depressurizing the cooking vessel.
The steam pressure used in the second stage should also be
between about 10 p.s.i.g. to about 25 p.s.i.g., preferably from
about 15 p.s.i.g. to aboùt 20 p.sOi.g.. As with the first stage
cooking, the steam is preferably supplied as superheated steam or
as almost saturated steam. The cooking temperature should also
be from about 240F to about 260F, preferably from about 250F
to about 260F, for about 25 minutes down to about 10 minutes
preferably about 20 minutes down to about 15 minutes.
- The two cooking stages can be in the same cooking vessel or
in serially operated vessels. The former is preferred because it
requires less handling of the oats. At the end of the first
stage cooking, fresh water is added to the cooker to increase the
water content to the above-described range and the second stage
cooking is commenced. The time lapse between the first stage
cooking and the second stage cooking should be kept to a minimum
not only to reduce operating times, but also to avoid unnecessary
tempering.
If the oats are tempered before shredding, shred strength
decreases with increased tempering times. Continuous shreds
'L~
which are strong enough to be easily handled in shredding rol]
operations cannot be ob~ained with tempering times over about
four hours. This is surprising because it has been necessary to
temper wheat for longer periods of time to obtain proper shreds.
In the production of shredded oats according to the process of
the present invention, no tempering before shredding is
preferable so as to permit a continuous process and to increase
shred strength. However, if tempering is used, it is
accomplished by limiting tempering time to about less than four
hours.
A two-stage cooking step is preferred over three or more
cooking steps because it involves less material handling. Either
of the two cooking stages described above can each be performed
in more than one stage so as to prevent the substantial
extraction of gums and water soluble starches and to prevent the
buildup of a barrier on the oat particles to water penetration.
Cooking times, temperatures, steam pressures, and amounts of
water used in any additional stages should generally be within
the above-described ranges.
Pressure cooking in only one stage by continuous addition of
water during cooking would require contxolled water addition to
the oats such that the rate of absorption of water by the oats
does not result in excessive extraction of the water soluble gums
and starches. While such a one-stage pcessure cooking step can
be used, it is less preferred than a multi-stage pressure cooking
step because of difficulty in controlling the water addition.
First, the moisture absorption curve o~ the oats can vary
significantly from one batch to another. Moreover, addition of
19
~L2(~
the water on a continuous basis tends to cause condensation of
the steam in a substantially unpredictable manner which makes it
difficult to accurately control the total amount of moisture
absorption by the oat particles. Also, higher e~uipment costs
would be involved for continuously controlling the addition of
water into a pressurized vessel.
Afte~ cooking, the oat particles are cooled and surface
dried to stop further cooking of the oat particles and to produce
free flowing individual non-interconnected oat particles. The
non-sticky surface produced on the oat particles permits movement
of the cooked oat particles through material handling equipment
such as screw conveyors, hoppers, and flow tubes. Suitable
c~o/e~
temperatures to which the oat particles are aookod range from
abou-t 50F to about 80F, preferably from about 60F to about
C~7~/i~ q
70F. The oooking and surface drying should typically be
accomplished within about 5 minutes to about 10 minutes. The
cooling and surface drying are preferably performed
simultaneously. Approximately one percent to - four percent
moisture, based upon the weight o~ the wet cooked oats, should be
removed during surface drying.
Upon remoYal from the cooker, the oat particles are
considerably free flowing, but the cooling and surface drying
further reduces stickine~s to the point where at least
substantially all of the oat particles are discrete and will flow
individually through a hopper without exhibiting a tunneling
effect. Cooling and surface drying should be accomplished as
rapidily as possible, preferably within about 5 minutes, most
preferably within about 2 minutes, after the second stage cooking
~0
i
~21:~967
to minimize stickiness. Also, depending upon ambient conditions,
particularly temperature and humldity, cooling and/or sur3ce
drying can be carried out advantageously throuyhout, or at other
points during, transport of the oat particles to the shredding
rolls. Under hot, high humidity conditions, moisture will tend
to collect on the oat particles which could increase stickiness.
Cooling and simultaneous surface drying is preferably
accomplished using ambient air. However, other cooling and/or
surface drying processes such as refrigeration, vacuum cooling,
or combinations of processes, can also be used.
For optimum shreddability, the moisture content of the
cooked, cooled, surface dried oat particles should be about 39~
to about 43% preferably about 40~ to about 42% by weight based
upon the weight of the oat particles. These moisture contents
can be achieved in the cooling and surface drying step or by
additional dryingO Typically, the additional drying can be at
temperatures in the range of from about 60F to about 100F for
about 10 minutes down to about S minutes. At moisture contents
below about 28~, shreddability of the oat particles deteriorates
rapidly. The particles tend to crumble or shreds which are
produced are of low strength, thereby hampering the production of
long continuous shred layers on a shredding roll. Moisture
contents of Erom about 28% to about 493 based upon the weight of
the oat particles are suitable Eor shredding on shredding rolls.
The dried oat particles are then transferred, suitably by
means of belt conveyers, to a hopper which Eeeds a screw
conveyer. The latter transfers the oat particles to a series of
conventional shredding rolls or mills via flow tubes or hoppers
21
~2(1~7
The shreds, which can be produced in the form of net-like sheets
by each set of shredding rolls, are layered, cut, dried, baked,
toasted, and then the pieces ace packayed all in known manner as
for the production of shredded whole wheat biscuits. These
layered sheets can be cut to orm spoon-si~e rectangular biscuits
or other shapes typical of ready-to-eat breakfast cereals,
biscuits or crackers. Temperature profiles used in the oven for
drying, baking and toasting of the oats can generally be the same
as those used in producing shredded wheat biscuits. A suitable
temperature profile ranges from about 600F at the entrance to
the oven to about 150F at the exit of the oven. The total time
for drying, baking, and toasting ranges from about 6 minutes to
about 8 minutes.
Commercially available processing equipment can be used in
the present invention. The pressure cooker should be of the type
wherein steam can be passed in direct contact with the oats, and
removed while the vessel is agitated and/or rotated. Suitable
pre~sure cookers for use in the ~irst stage and second stage
cooking include a Lauhoff cooker, Buhler cooker or Baker Perkins
cooker. For transporting the cooked product after it is removed
from the second stage pressure cooker, a shaker conveyor, such as
a Rexnord carrier can be used. Suitable tempering equipment
includes a flat belt or bins.
Prior to cooling the cooked product, it is preferable tO
subject it to a lump-breaking operation in a rotar~ lump breaker
such as a Jacobsen lump breaker~ The cooked oats are preferably
cooled and simultaneously surface dried on a cooling reel, such
as one manufactured by LittleEord, in a Hess gcain-type dryer, in
22
~Z~6q
a vibrating screen cooler, in a Wolverine continuous cooler, or
combinations thereof. In the WolverineR cooler, jets of cool air
impinge on the vibrating oats from above to fluidize the oat
particles and thereby cool and surface dry them. Other suitable
cooling means include vacuum vessels and refrigerated conveyors.
Exemplary of the types of dryers which can be used o
additionally dry the cooled, surface dried oats are belt or
conveyor dryers, vacuum dryers and the like.
Shredding systems which can be used in the process of the
present invention may comprise conventional rolls and devices
such as those indicated in U.S. Patents 502,378, 2,008,02~,
2,013,003, 4,004,035, and Canadian Patent 674,046. A
conventional shredding mill for use in the process o~ the present
invention comprises a pair of closely spaced rolls that rotate in
opposite ~irections, with at least one of the rolls having
circum~erential groovesO Upon passing be~ween the rolls, the
wheat is deformed into long individual strings or shreds. The
circumferentially grooved roll can also be grooved transversely
to the circumferential grooves ~or the production of net-like
sheets. When the rollers are held to roll in mutual contact, the
shreds or filaments will be fairly separate from each other,
though more or less contacting, but when the rollers are sprung
slightly apart, under pressure, the adjacent filaments may be
united to each other by very thin translucent, almost
transparent, webs or fins between them.
The shredding mill.s are typically arranged in a linear
series along a common conveyor, with the shreds running
longitudinally or in parallel with the direction o movement oE
23
~2~ q
the conveyor. The sheets or layers of filaments are deposited on
the conveyor in super-position, with their eilaments running ln
the same direction. A typical biscuit, for example, may contain
up to 21 individual layers of shreds. Upon obtaining the
requisite thickness, the multiple layer web can be cut
transversely and lonqitudinally into multiple lines of biscuits
in known ~anner. The cutting can be completely through the
laminate to form the individual biscuit shapes prior to baking~
Cutting partially through the laminate to form biscuit shapes,
10followed by baking, and separating the baked partially cut
laminate into individual biscuits in known manner is preferred
for easier control of the orientation of the cut product as it
passes through the baking oven.
Suitable ovens for drying, baking and toasting the shredded
product include Proctor & Schwartz, Werner Lahara and Spooner
ovens con~aining forced air and gas fired burners and a conveyor.
Many grains requir2 different cooking times, different
tempering times and differen~ temperatures to obtain optimal
flo~ability properties, shred strength, appearance, and the like.
20Accordingly, to produce-a cereal product having a mixture of
different types of cereal grains in each biscuit, it is
preferable to separately process each type of grain and to then
co-shred the grains. It is al50 possible to combine the separate
grains by separately shredding the grains and then layering the
shreds of the different grains.
The other grains can be prepared for shredding by
conventional methods or by the process of the present invention.
Exemplary of the other grains are harley, rye, corn, wheat,
2~
967
combinations thereof, and the like. Use Oe the multi-stage
pressure cooking step of the present invention has been found to
eliminate the need for or reduce the amount of tempering oE these
grains. Steam pressures, cooking times, and temperatures,
cooling conditions, drying and baking conditions can generally be
the same as those described above for the peoduction of shredded
oats Adjustments, however, can be made to achieve optimum
flowability and shreddability by slight changes in moisture
content, steam pressure, and cooking time.
The oats can be cooked with one or more other food
ingredients at the usual levels of concentration, which do not
interconnect the oat particles or otherwise interfere with the
attainment of individual, discrete, free-flowing oat particles,
for the continuous production of shreds. Thus, for example, the
oats can be cooked with a sugar such as sucrose, salt, malt,
flavoring, food colorant, emulsifier such as MyvatexR (a blend of
distilled monoglycerides manufactured by Eastman Kodak), vitamins
and~or minerals. ~owever, products made from only whole oat
groats and/or only other grains are preferred because of their
appeal as a 100% natural ~roduct.
The present invention is further illustrated in the
following examples. All percentages, parts, and proportions are
by weight and all temperatures are in F unless otherwise
indicated:
EXAMPLE l
In this example, both stages of the cooking step are
conducted in the same pressure cooker. To a Johnson cooker is
~12~ E;7
added l,000 lbs. of whole oat groats (commercially available from
Con Agra) having a moisture content of about 10 percent by weight
(O'Haus). Then 130 lbs. of water, at a temperature of about 55F
is added to the cooker. The cooker is closed and steam at 15
p.s.i.g. and lO0~ saturation is passed through the cooker in
direct contact with the oats for 15 minutes. The steam is shut
off and the cooker is opened for the addition of 425 lbs of
water. The water which was added was at a tempecature of 150 to
170F. All of the water was added in less than three minutes.
The cooker was then closed, steam was supplied at 15 p.s.i.g. and
100% saturation for an additional 15 minutes as in the first
stage. The steam was then shut off and the cooker opened. The
cooked oats were dumped onto a shaker conveyor, passed through
two lump breakers and then fed to a Littleford cooling reel.
Cooling, accompanied by surface drying, was conducted to reduce
the temperature of the oats to about 90F.
The product discharged from the cooling and drying reel was
collected in a drying bin equipped with its own fan and
perforated screen bottom. The temperature of the air used to
further cool and surface dry the product was about 70F. Drying
was conducted for about five minutes to obtain a product having a
temperature of about 80F and a moisture content of about 423 by
weight. The dried product was transported to a shredding line
hopper and shredded in a conventional shredder having a five-inch
chain conveyor. A shred layer about 4 l/2 to about 5 inches wide
was obtained. A laminate of the shred layers is formed and cut
to obtain spoon-sized pieces. These pieces wece then baked in a
Spooner oven for about 7 minutes at a temperature of about 600F
26
~a~6q
to produce baked spoon-sized 100% whole oat biscuits having a
moisture content of about 5~ based upon the weight of the final
biscuit product.
The shred quality was strong and the shred layer pattern was
the same as the shred pattern of shredded wheat.
EXAMPLE 2
This example is carried out in a similar manner as Example 1
except that the cooked oats are fed to a Wolverine~ continuous
cooler instead of to the Littleford cooling reel and drying bin.
The oat particles are cooled and surface dried to a temperature
of about 80F and a moisture content of about 42% by weight,
respectively, by the continuous cooler. The shred quality and
shred pattern are the same as obtained in Example 1.
27
