Note: Descriptions are shown in the official language in which they were submitted.
10493Z0
The art of preparing a ready-to-eat pufed cereal
product has advanced significantly from its inception in the
early part of the 20th century. This cereal form has now
assumed the prominence of being a standard in the industry
having certain characterizing structural and eating features
which may be stated as follows; the flake is uniformly blist-
ered as well as uniformly colored and has the appearance of
substantially uniform thickness as a consequence of such
blistering, the edges of the flake being preferably scalloped
or irregular and the flake itself being generally curled if not
cupped. Good manufacturing practice requires that such a flake
be produced by a process which is sanitary, easily controlled
and continuous.
Processes have been described which enable the con-
tinuous cooking of a ready-to-ea-t breakfast cereal product,
i.e., United States No. 3,062,657 issued November 6, 1962 to
Vollink for Process for Producing Breakfast Cereal Flakes.
This process describes means whereby a farinaceous cereal
material may be advanced in a continuous, high-temperature
extrusion path that eventuates into a low-temperature termina-
tion point, whereupon the cooked mass is pelletized and con-
verted into flakes. The cooked material is typically extruded
through a cooling zone and a die plate whereby the dough mass
does not undergo expansion but rather substantially retains its
doughy plastic cooked condition in an unexpanded condition.
The art involved in providing a highly blistered surface after
rolling the flakes to a condition wherein they may be toasted
at elevated temperatures using radiant heat or forced hot air
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still leaves something to be desired in achieving the foregoing
objective of breakfast cereal flake crispness and uniformly
blistered and colored appearance.
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Uniformity of cooking coupled with control of toasting are
important considerations to achieving a uniformly blistered
structure and yet there remains a need to ad~ance the art of
achie~ing such uniformity in a continuous cooXing system.
More recently invented processes described in U.S.
No. 3,453,115 issued July 1, 1969 to Clausi et al. for prepara-
tion of Ready-to-Eat Puffed Cereals provide means whereby the
cooked pellets may be flaked and fluidized in a hot air stream
and thereafter toasted to achieve a golden puffed corn flake
product.
The merging of these arts would pro~ide a significant
advance in ready-to-eat puffed cereal flake manufacture, and yet
improvements remained prior to the present invention in respect
of a need for a uniformly puffed flake structure as aforementioned.
In accordance with this invention, a blistered uniform
preferred eating texture is afforded a cornflake by converting a
mid-sized cereal meal that is comprised predominantly of corn
meal substantially free of free starch and grits into a coo~ed
cereal dough wherein fla~oring syrup is infused. The cooked
dough is pelletized after being cooled to below 210F., the
pellets are dried to less than 20~ but above 13% moisture, and
the dried pellets are then tempered to be plastic preparatory to
flaking. The flakes are then subjected to fluidized bed blister-
ing in a first zone wherein water vapor is caused to be uniformly
flashed from the surfaces thereof in less than one minute with a
collateral 25% - 75~ moisture reduction, the blistered fla~e
being thereafter toasted to a stable moisture content, preferably
in a second fluidizing toasting zone.
The foregoing narrative statement of the key steps in
the process merges some arts that are known ~o skilled art work-
ers including those of continuous cooking, p~lleting and flaking:
accordingly, a detailed description of such arts is unnecessary
`~` ` : ` : ' .
10493Z0
and may be drawn from the operative best mode described herein-
after, the practices of coo~ing, pelleting and flaking not being
critical to this invention except as disclosed.
One necessary feature that is uncommon and is not fully
understood is the requirement that farinaceous cornmeal flour ~e
of a size which is substantially free of very fine flour and
coarse grit particles. The most preferred blistered flake has
only been pxoduced when such a particle size distribution in the
starting material is employed, although less than 15% by weight
of said very fine and coarse particles in combination as speci-
fied in the operative example can be present in the starting
meal. By selecting the mid-sized corn meal, as specified herein,
combined with syrup and 25~ - 35% added moisture and cooking it
in a continuous reactfon vessel such as positively and consist-
ently advances the dough undergoing gelatinization, there is a
uniform cooking and infusion of flavoring in the farinaceous
particles. This is significant since it is important not only to
cook the dough uniformly but also to avoid overcooking it,
whereby the eventual toasted puffed flake retains a texture
which causes the rehydrated flake to disintegrate through
fracture of flake structure per se rather than conversion to a
mush. This rehydration characteristic -~s afforded by pressure
cooking the hydrated corn dough mass with a minimum of mechanical
shear intermediate continuously rotating blades and a circum-
jacent heating barrel. A minimum of fine flour particles avoids
overgelatinization such as detracts from this intended flake
struc'cure; a minimum of oversized grit particles likewise assures
intended flake disintegration and uniform gelatinization.
Mid-si~e corn meal fraction also assure that the cooled
extrudate can be col}ected and handled without excessive subse-
quent clustering of the pellets. To explain, it's important that
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10493Z0
the pellets of cooked material remain essentially discrete so
that they can be pneumatically conveyed or otherwise trans~erred
to the next primary station where they are partially dried.
Sticky pellets can adhere to one another and clog a system; in
like manner, sticky moisture-laden pellets of overgelatinized
material can cluster and dry as such. A uniformly cooked pellet
is important to insure smooth and consistent downstream proces-
sing. Thus, it is important to pr~vide a discrete partially
dried pellet which can be individually flaked and will toast
pneumatically as such.
In this regard it will also be advantageous to employ
0.1 to 1.0~ of mono- and or a mono- and diglyceride emulsifier
in the starting meal; the cooked cooled pellets are less sticky
and will dry discretely, permitting facility in recovery from
drying screens and a discrete condition for later flaking and
fluidized bed toasting. It appears that the mono-glycerides
comple~es the free starch sufficiently to result in such smooth
cooking as will minimize any tendency in the pellets to stick by
reason of overgelatinization of the starch.
The screen fractions of a typical corn meal used for
pelletized corn flakes in accordance with this invention, will
~e as follows:
SCREEN FRACTIONS OF CORN MEAL USED FOR
PELLETIZED CORN FLAKES
on USS 16 mesh 11.0%
" " 18 " 30.0%
" " 20 " 17.0%
" " 25 " 31.0%
" " 30 " 10.0%
thru " 30 " ~.D~
These fractions are determined by conventional Rotap
sieve procedure using a 5 minute tap.
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~049320
In general, at least 85% by weight of the ~eal will
pass a USS 16 mesh screen and essentially at least 5~% by weight
of the meal used will be retained on a USS 25 mesh screen after
passing a USS 16 mesh screen. Thus, as seen from the foregoing
typical screen analysis, a major weight percent of the corn meal
particles will not only be free of very fine essentially endo-
sperm starch-containing granules, but also a large majority of
the granules will be distributed uni~ormly in a particle size
distribution pattern, despite the coarseness of the meal. While
it is difficult to establish and only a theoretical ~bser~ation,
it is believed that in a continuous cooking operation where sus-
tained processing to achieve the ultimate cook is required absent
a sticky condition, such uniform corn meal particle size granula-
tions will assure even distribution of the chemical and
corresponding physical properties of the particles providing
ideal pelleting, flaking, toasting and incidental handling
properties.
Also, as indicated herein, it will be desired that a
majority of the uniformly cooked starch granules will have been
gelatinized to the point that they will lose their birefringence
as viewed under polarized light: on the other hand, avoidance of
excessive mechanical shear is believed important to avoid the
presence of high order of free starch that has been overgelatin-
ized.
The cooked dough, produced by continuously heating the
meal and syrup is converted into a pelletized mass that should be
cooled ~o well below 210F (e.g. 100 - 185F) preparatory to
issuance from an extrusion nozzle or shaping die whereby the
extrudate does not undergo su~stantial puffing or moisture loss;
for this purpose, therefore, the cooled dough will be at a
temperature well below that point at which the water vapor of
the dough mass will flash; ideally the dough will be cooled to
104~3Z0
about 150F as it is admitted to atmospheric conditions it has
been observed that at product temperatures above 185F there is
a noticeable tendency of the pellets to stick with the afore-
mentioned processing difficulties resulting.
The cooked pellets should be dried in as discrete a
physical state as possible to between 13~ - 20~ H2O. A distilled
monoglyceride in a level of about 0.75% of the meal aids in pro-
cessing to permit such ideal drying conditions.
An important refinement will be the tempering of the
pelletized dough over a sustained period under ambient conditions
wherein the product will have a uniform plasticity rendering it
flakable to a point where the cooked dough moisture is uniformly
distributed; generally, this is evidenced by a scalloped appear-
ance at the edge of flaked, tempered pellets and by a uniform
flaked pellet surface free of breaks. In this context, the
phrase "ambient conditions" is intended to connote that no
external heat of any consequence is applied, it being a preferred
embodiment of this invention that the pellets be flaked at a
temperature about 90 - 150F whereat they exhibit sufficient
plasticity incident to rolling to uniformly respond to the rol-
ling pressures of the fla~ing rolls after tempering for one to
three hours.
Tempering of the pellets is quite consequential when
related to the blistering conditions that are employed to set the
flake structure upon introduction to the fluidized high tempera-
ture drying gas; this gas is typically air. The jets of
fluidizing medium are directed into a vibrating trough or similar
- vessel operative to reflect the high velocity gas jets and
redirect the volume of drying gas back upwardly in the direction
of the flake charge admitted over this fluidizing medium. The
flakes are preferably advanced through a plurality of such
fluidizing zones as described hereinafter and are sequentially
104913Z~
turned so that water vapor is uniformly generated within the
flake and is uniformly expanded as can be practiced in apparatus
for this function described in U.S. 3,060,590 to Wolverine
Equipment Co. for Method of Treating Discrete Particles issued
October 30, 1962. This treatment causes uniform discrete
blistering as specified herein. It is believed critical to this
fluidizing invention that fluidized blistering be caused to
transpire over a period less than a minute preferably less than
45 seconas, the minimum time for blistering being to some degree
a function of the limitations of the fluidizing gas temperature
which exceeds 300F and its velocity; generally at least 15
seconds is required for proper blistering of flakes to cause
moisture content reduction between 25% - 75%, typically about 50%,
and until a moisture co~tent of between 5% - 10% and typically
8% is achieved. The extent of blistering will be dependent upon
the initial moisture content of the flakes and its distribution
- through tempering: as indicated, the pellets are dried prepara-
tory to being tempered and the extent to which the pellets are
dried has a bearing on the degree to which the flakes should be
dehydrated incident to being blistered; it is believed that at
higher moisture contents a higher level of moisture reduction
and a higher rate of evaporation will produce preferred flake
blistering.
The flaXe temperatures reguired to achieve this uniform
blistering will be such that the blistered flake charge will
exhibit a sensible heat of at least 250F when measured by a
thermocouple inserted into a bed thereof after the zone of
fluidiæation has been rendered inoperative; generally, the blis-
tered flake at this point should not exceed 350F. Once the
fluidized and blistered flake is produced, it is ideally consecu-
tively rapidly toasted in a second like fluidizing toasting zone
wherein fluidizing gas temperatures are operative to carmelize
10493Z0
the product to a brown golden hue and result in terminal moisture
reduction to 2~ - 3~, the product blisters being thereby hardened
and flavor and color being uniformly developed. The preferred
fluidizing toasting zone may be dispensed with and in lieu
thereof a more conventional toasting oven employed. In all of
the toasting applications, product temperature will ~e elevated
to above 275~F and commonly in the neighborhood of 300 - 370F,
measured as before in the case of blister fluidization. In this
art product temperature is the ambient temperature of the fluid-
izing gaseous medium, which the product will substantiallyapproàch the term product temperature is thus reasonably under-
stood by workers to be the gas temperature in the plenum chamber
for entering fluidizing gas. Generally, toasting should
consecutively follow fluidized blistering with a minimum of
elapsed time such that blistered flakes are above ambient
temperatures as they are delivered from the fluidizing zone to
the toasting zone.
A corn flour meal having the aforementioned size
distribution wherein 90% is retained on a USS No. 30 mesh screen
and 85~ passes a USS ~o. 16 mesh screen is formulated as follows:
Formula - 80% corn flour, 8% sugar, 1~ salt, 1% malt
flavoring, 0.75~ distilled mono-glyceride and trace ~ coloring.
Processing - Sufficient water is added to the ingredi-
ents to form a mixture containing approximately 30% moisture.
The wetted mixture is fed into a screw type pressure lock wherein
the mixture form a continous pressure charge entering a contin-
uous cooker of the type described in U.S. Patent No. 3,062,657
cited hereinabove and generally comprising a rotating screw
within a steam jacketed complementary ~arrel serving to contin-
uously heat and gelatinize the syrup produced ~y dissolving thesugar-salt flavoring in the make-up water. This mass is heated
for approximately 15 minutes at 20 pound steam pressure and the
starch content will be substantially digestible and fully cooked.
49 3 Z O
The cook-in~ mixture does not fully occupy the chamber
space intermediate the rotor blades a~d the chamber itself and
the bla~es serve to advance the mix~ure with a tumbling mixing
action to uniformly treat all of the particles and cause them
to merge with one another in producing the intended dough,
there being virtually no localized accumulations of flavoring
syrup and instead a rather uniform impregnation thereof in the
cooked dough mass. The dough mass is then gravity-discharged
with a free-fall to an extruder wherein the cooked dough under-
goes a gradual cooling between the screw and barrel surfaces asit advances to a die plate; the cooling of the dough serves to
assure that it will not expand subsequent to issuance from the
cooker to an extent greater than that which it has achieved
through the effects of hydration in the cooker per se.
Although the temperatures to which the dough mass is
elevated during cooking is not a critical aspect of the inven-
tion, a preferred upper temperature limit will be 300F gen-
erally whereat earmelization and other flavor reactions are
minimized and only that amount of heat treatment is provided to
gelatinize and develop intended flavor. The discharged cooked
mass that is cooled by the extruder issues therefrom at about
150F and has a moisture content of about 30%.
The cooked pellets, say 3/16 long and of li~e dia-
meter, are next pneumatically conveyed to a through-circulation
belt drier wherein they are dried in an oven to broadly 14% -
20%, preferaly 15% - 18% moisture and thereafter tempered for a
period of about two hours until the pellets have a uniform dis-
tribution of the moisture content herein and are uniformly
plastic and non-sticky. The pellets are thereby in a condition
~ g _
,.
~ 0493ZO
to be ~laked between a pair of oppositely rotating flaking
r~lls set at a gap thickness commensurate with producing a
flake having a thickness of about 0.018 inch and
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1049320
exerting a fla~ing pressure of about 36,000 psi at the nip; the
rolls may be adjusted to have variable rolls speeds where
accentuated curling is desired in the flake preparatory to
blistering and toasting. At this point the flaked dough sur-
face is uniform and free of surface breaks on the flattened
regions thereof whereas the perimeter of the flakes are essen-
tially shape-retaining and in a condition to be subjected to
the blistering and toasting practices of the invention.
A charge of the tempered flakes is introduced in a
first fluidizing zone wherein a plurality of high velocity air
jets are admitted proximate one another downwardly over in
proximate relation to a bed of the f la~es at an air temperature
of approximately 400F for about 30 seconds; in this zone the
flakes will be retained on a vibrating trough-conveyor adapted
to fluidize the flakes by deflection of the high velocity air
flow around and upwardly through the charge. The velocity of
the circulating air within the bed is such as to provide an
air pressure of about 2.0" to 2.7" of water as measured by a
magnihelic gauge connected to Pitot tubes inserted into the
plenum supplying the air to the aforesaid air jets; velocity
in relationship to the charge material will be such that
substantially all of the tempered flakes will be fluidized and
the flakes themselves will undergo uniform flashing of water
vapor therefrom, thereby resulting in a discrete yet uniform
blistered appearance while being only slightly changed in color.
The bed of flakes is more or less randomly poised above the
trough area, the suspensibility of the flakes being such that
they turn individually and independently of one another in
random manner to provide uniform surface blistering on both
surfaces thereof. In the trough flakes are advanced horizon-
tally and initially intercept a vertical series of fluidizing
nozzles which cause the fla~e to be elevated under influence of
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~04~13ZO
trough vibrations. Once the thrust of a series o~ vibration
causes the flakes to be fluidized, they are sequentially
exposed to alternating zones of fluidization defined by
staggered sequential rows of high air velocity iets poised
a~ove the trough and creating the fluidized condition just
described.
As a result of fluidized bed blistering as just
described, the product will undergo a flashing of approximately
S0~ of its moisture content and thus will be of a moisture
content of about 8~.
~pon completion of the 30 second blistering cycle,
the flakes will be transferred by a conveyor to a second zone,
a fluidized toasting oven like the first, operating at a
fluidizing air pressure of 1 to 1.5" of water wherein the flakes
will be toasted by hot air at 275F - 370F or approximately
310F for 30 seconds or until a uniformly golden hue results
and during which toasting virtually no further consequential
blistering may be observed. Proauct passing the toasting zone
undergoes a further moisture reduction to about 3%.
The toasted blisters per se are discrete and the walls
therefore relatively continuous in that they have a minimum of
visible broken areas, although some isolated instances of
blister rupture may be apparent on each flake.
The product when consumed in milk retains its
crispness for a reas~nable recipe period~ is quite flavorful
and has the preferred blistered corn flaXe texture described
in the preamble of this specification.
While the invention has been described by a detailed
depiction of the best mode for practicing it, variations will
occur to men skilled in the art.
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