Note: Descriptions are shown in the official language in which they were submitted.
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FRENCH FRYABLE FROZEN POTATO STRIPS
AND METHOD OF MAKING THE SAME
The present invention relates to frozen potato
strips which are French fryable and to a method of
preparing French fryable potato strips for freezing.
For producing quick-service French ~ried
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potatoes, it is important that a stock of French fryable
potato strips be available to meet varying demands.
Customers prefer to have French fried potatoes that have
the texture, flavor and odor of freshly deep fat fried
raw potatoes, but they do not want to wait to have such
potatoes cooked. Consequently, it is desirable to be -`
able to subject the potato strips to a very brief final
heating or finish cooking while producing an attractive
and palatable productO
The demand for French fried potato strips is
not particularly seasonal, yet the growing of the potatoes
from which they are made is seasonal. Consequently, it
is necessary to utilize a practical method of preserving
potatoes, or French fryable potato strips, for a con-
siderable period of time, up to a year, and it is
customary to accomplish such preservation of French
fryable potato strips by freezing. A stock of frozen
French fryable potato strips thus can be accumulated
immediately following the potato growing season and the
stock can be distributed as needed to meet the sub-
stantially constant demand for French fryable potato
strips throughout the following year.
Frozen potato strips have been used for making
quick-service French fried potatoes, but such French
fried potatoes have generally not been of the best
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quality, having one or more of the characteristics of
sogginess, pale color, lack of crispness, poor flavor, a
leathery shell and an interior that is undercooked or
pasty instead of being mealy throughout.
In some instances, prior to being frozen,
potato strips have been blanched, as in Strong United
; States patent 3,397,993 issued August 20, 1968, and
Wilder United States patent 3l649,305 issued March 14,
- 1972, or partially cooked in water, or partially deep
fat fried, or partially dehydrated, or subjected to some
combination of such process steps. Such French fryable
~ strips often have not been of good quality.
; The Katucki et al. United States patent 3,359,123
issued December 19, 1967, proposes to use heated air for
partially cooking whole unpeeled potatoes prior to being
frozen, but the potatoes are dehydrated after being
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frozen rather than prior to being frozen.
The potato strips of the Barskey et al. United
States patent 2,565l942 issued August 28, 1951, are
partially dried or cooked in water prior to being frozen.
` The Kaehler United States patent 3,244,538
issued Aprll 5, 1966, proposes to subject potato strips
~' to a preliminary drying step using dry heat or superheated
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~` steam prior to the potatoes being frozen, but any cooking
effect which occurs extends only to the exterior of the
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i~ potato, leaving the intexior substantially uncooked or
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raw.
It is an object of the present invention to
;-` provide a procedure ~or enabling Fxench fryable po-tato
Ii strips to be prepared quickly and effectively for frozen
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~ storage while maintaining a high quality of such strips.
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Moreoever such frozen French fryable potato
strips can be finally deep fat fried quickly for
consumption.
A further object is to provide a method of
preparing French fryable frozen potato strips which
conserves energy by minimizing heat required to cook
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; and/or dry such strips.
Despite the advantages of the process of
preparing French fryable frozen potato strips according
to the present invention, such strips when finally fried
even without being thawed first have an appearance,
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~ texture, flavor and odor comparable to raw potato strips
: which have been French fried without having been frozen.
~: The foregoing objects can be accomplished by
a process for producing frozen potato strips for French
frying, which comprises dividing raw, unblanched potatoes
~ into strips, circulating humid hot air over the surfaces ;
;~ of such strips in unblanched, substantially raw condition
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until the strips are partially dehydrated and partially
gelatinized substantially throughout, weigh about 85% to
90% of their weight when raw and have a finely granular
cell structure, circulating substantially dry hot air
over the surfaces of the strips until -the strips are
further partially dehydrated and their weight is about
75% to 80% of their weight when raw, and thereafter
freezing the strips without the strips having been
blanched.
Such objects can also be accomplished by a
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process for producing French fried potatoes which comprises
dividing raw, unblanched potatoes into strips, heating
` the strips until they are partially gelatinized substan-
tially throughout, partially dehydrating the strips
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until the partially gelatini~ed and partially dehydrated
strips weigh about 75~ to 80~ of their weight when raw
and the cell structure i5 finely granular, parfrying
the partially gelatinized and partially dehydrated
strips, freezing the parfried strips, and thereafter
finish frying the strips without the strips having been
blanched.
Potatoes of a variety known to be suitable
for French frying and in suitable condition are sorted,
peeled and trimmed in accordance with conventional
practice and are then cut into strips of a size customarily
used for French frying, such as of a width and thickness
1/4 inch (6.35 mm) to 1/2 inch (12.7 mm) and several
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inches (more than 10 cm) in length. After such strips
are cut, they can be washed to remove surface starch.
; French fryable potato strips thus prepared can
be treated by dipping or briefly soaking them in an
antioxidant solution, or spraying them with such a
solution, to inhibit discoloration of the potato strips
by oxidation on exposure to air for a prolonged period.
~` The solution may be a 1/2% to 1% by weiyht aqueous
solution of sodium pyrophosphate (Na2H2P2O7), sodium
; 10 bisulfite (NaIlSO3), citric acid or other known discolora-
tion inhibitor. The treating solution also may include
reducing sugar, if desired, to facilitate browning of
the potato strips when being finally deep fat ~ried
ready for consumption. The treating solution may be
heated to a temperature of 130 F. to 180 F. (56 C. to ;~
82 C.) and the potatoes may be subjected to the action
of such a solution for a brief period within the range
of 10 seconds to 25 seconds.
The potato strips then are subjected to heat
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- 20 at a temperature, for a time and under conditions which
~` will partially cook and partially dehydrate the potato
strips, such that the metabolic functions are deactivated,
as evidenced by gelatinization of the starch. The
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affected potato material progresses toward a finely-
granular condition in which the granules are easily
separated. The potato strips are placed in an enclosure
and hot air is circulated over their surfaces. The
cooking and dehydrating operations can be performed as a
;~ batch process or as a continuous process, and the potato
strips can be stationary or moved on a belt through a
heated cha~er.
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The processing apparatus can be designated as
a heating enclosure. The heating oE the potato strips
can be effected entirely by high velocity currents of
air heated by a heat exchanger, or heating effected by
the air can be supplemented by auxiliary heat sources
such as infrared or microwave heaters. The degree and
penetration of cookiny will depend on the condition and
variety of potato, the cross-sectional size and shape of
the strips, the type or types of heat source or sources,
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the temperature, humidity and velocity of the heating
air and the length of time that the strips are subjected
to heating.
The first stage of heating is to xemove surface
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~ moisture from the potato strlps. The temperature of the
:' initial air blown onto the strips may be within the
` range of 190~ F. to 280 F. (88 C. to 138 C.), and
preferably within the range of 250 F. to 280 F. (122
`` C. to 138 C.). The moisture content of the air shouldbe less than 15% by weight so that the air currents will
scavenge moisture readily from the surfaces of the
~; potato strips in a period of 1 to 3 minutes. During
such treatment, no appreciable moisture will be evaporated
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from the interiors of the potato strips.
~i During a second stage of heating, the potato
strips are subjected to currents of hot humid air in the
temperature range of 200 F. to 250 F. (94 C. to 122
C.), preferably within the range of 230 F. to 250 F.
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(110 C. to 122 C.), for a period of time sufficient to
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partially cook or ~elatinize the strips and partially
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~ dehydrate them, in about three minutes to six minukes.
`~ The strips will be cooked to at least some degree close
~: to the center but the outex portions of the strips will
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be cooked to a greater exten-t. Moisture evaporated from
the potato strips tends to increase the humidity of the
air as it is circulated. It is preferred that the
moisture content o~ the air be within the range of 15%
to 40% by weight. The recirculating air humidity is
controlled so that the potato strips will be dehydrated
to the desired extent while simultaneously belng partially
cooked. Such humid air can penetrate more effectively
into the potato strips to cook them. The partial cooking
modifies the cell structure of the potato so that the
metabolic functions are deactivated and the starch is
gelatinized, resulting in a finely granular condition in
which the granules are so~t but not mushy and are easily
separated. Such a texture is designated as "mealy".
The air moisture content can be regulated by
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controlling the amount of dry air admitted to the heating
chamber and the amount of moist air discharged from the
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chamber. During the cooking-evaporating treatment, the
` moisture content of the potato strips will be reduced so
that the partially cooked and partially dehydrated
strips will have a weiyht of 85% to 90% of their original
weight.
During a third stage of heating the potato
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strips are subjected to heat which will dehydrate them
to a weight of 75% to 80% of their original weight.
- Such heating may be effected by comparatively dry hot
air, such as having a moisture content less than 10% by
weight, which may or may not be supplemented by infrared
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or microwave heating. During such dehydration step,
much of the heating air is exhausted or dried to main-tain
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the low moisture content specified. Such dehydrating
~` operation may be accomplished in two to four minutes.
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More moisture will be removed from the outer portions of
the potato strips than from the inner portions. The
surfaces of the potato strips will be dry to the touch,
and the edges and corners of the potato strips may be
almost totally dehydrated. Such dehydration procedure
will result in a shell or crust on final deep fat frying
which will be crisp but tender and not leathery.
The potato strips that are subjected to the
cooking dehydrating operation discussed above have not
previously been blanched with steam, have not previously
been soaked in water and have not pre~iously been cooked
in water. The antioxidant treatment by spraying or
dipping is of sufficiently short duration so that the
potato strips do not absorb any substantial amo~nt of
moisture during such initial treatment. Consequently,
it is not necessary for the heated air to remove from
the potato strips any substantial amount of artificial
moisture which they have acquired, but, on the contrary,
during the cooking-dehydrating operation, it is almost
entirely the natural moisture of the potato strips that
is evaporated. Consequently, the drying-cooking-
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dehydrating operation is performed more rapidly, and bysupplying less heat energy, than would be required if
the potato strips had picked up any substantial amount
- of artificial moisture prior to or during the cooking
operation.
: Following the drying-cooking-dehydrating
operation described above, the partially cooked and
partially dehydrated potato strips can be allowed to ..
cool briefly and then somewhat deep fat fried quickly,
such as for a period of 1/3 of a minute to 2 minutes,
depending on the temperature of the cooking oil and the
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size o~ the potato strips and the desired solids contents
~ of the strips. PreEerably the cooking oil is within the
; temperature range of 325 F. to 390 F. (163 C. to
199 C.). This preliminary deep fat frying operation
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removes additional moisture from the potato strips, the
amount removed depending on the size of the strips, the
temperature of the cooking oil and the duration of the
preliminary frying step.
~ The potato strips then are frozen in a conven
,, 10 tional manner and held in frozen condition until they
are ready to be prepared for consumption by being subjected
to the final deep fat frying operation. Such final
frying operation can be accomplished without first
thawing the pota-to strips and wi-thin a period of 1-1/2
: minutes to 3 minutes if the cooking oil is at a tempera-
ture within the range of 3~0 F. to 380 F. (171 Cn to
193 C.). The resulting French fried potato strips will
have a crisp exterior without being leathery, will have
a substantially homogeneous mealy interior and will be
of golden brown color. Their flavor and odor will be as
pleasant as those of raw potatoes which are French fried
without ever having been frozen.
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