Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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POTATO S~7AC~C PRODUCT
Background of the Invention
This invention relates to food snack products, and more
particularly to a method for making a novel expanded potato
snack having a texture and flavor closely resembling that of
fresh potato chips. ;
Potato chips are well known snack products prepared by
frying thin slices of raw, fresh potatoes. Several reasons
for the commercial success of potato chips are their crisp
texture and fresh potato flavor, and their suitability for `
mass production techniques.
Since the time potato chips fi~st became a commercial
success, food processors in this country and abroad have
attempted to produce a prefabricated potato-based snack
product which captures the flavor and ~exture of frash potato
chips, and which also has an appearancà or structure similar
to potato chips, and which can be manufactured in high volume ~;
at a relative low cost. Generally speaking, most prior art
"expanded" potato snacks ti.e. snacks produced from a potato-
based dough which is expanded to a porous condition by
immersion in hot cooking oil) have not been successful
commercially because they do not have the combined flavor and
crisp texture resembling that of potato chips, together with
the capabili~y of being mass produced at a relatively low cost.
The prior art prefabricated potato snacks generally can
be grouped in four categories which include (1) the dry collet
process, (2) extrusion of dry potatoes, (3) forming a high
solids content dough into a thin sheet, cutting, and frying,
and (4) forming and frying potato snacks directly from a `
relatively moist dough.
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(1) In the dry collet process, a dry, thin portion of a
starch-based gel, commonly termed a "collet", is expanded by a
short immersion in hot fat. Typically, mixtures of potato
solids and various starches are cooked to completely gelatinize
all the starch molecules. The starch gels typically have a
relatively high solids content, i.e. usually over 60% by weight.
The products are held or cool~d to reduce the stickiness of the
gel, and are later sliced or cut into desired shapes and dried
to form a hard pellet. The products are expanded to about
three to six times their original thickness when immersed in
hot fat. The entrapment of steam bubbles in the heated starch
gel creates a uniformly porous structure when the snack is
viewed in cross-section.
The processes disclosed in U.S.Patent No. 2,863,720 to
Speiser and U.S. Patent No. 3,131,063 to Gerkens are typical dry -
collet processes in which dehydrated potatoes and starch at
about 65% solids are gelatinized at high temperatures and
pressures during extrusion, and then cut and dried to form dry
stable collets.
Control of the dried collet processes, such as that
of Speiser, is difficult and expensive in continuous operation
primarily because of the interruptions required to allow the
gels to become firm and less sticky so they can be cut or
sliced and d~ied. The final puffed product is extremely soft
in texture, there is little initial bite, and it tends to lack
the flavor of fresh fried potato chips. ~-
The potato snack product produced in accordance with
the method of this invention has novel structural aspects ` -
which will be described in detail below. The structure of~the
present snack product will be understood best by comparing it
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with the structures of the prior art snacks by referring to the
accompanying drawings which are described in detail below.
FIG lA is a cross-sectional elevation view showing the internal
structure typical of the snacks described here in category (1).
(2) In the dry extrusion process, dry starch-containing
granular materials such as potato solids and corn meal are used.
The moisture content of the material is normally between 12% to
1~ by weight. The granular solids are fed into a single screw
extruder operated at high speed and close tolerance to increase
the temperature and work the granular material, thereby
gelatiniæing the starch in it. The material is finally forced
at very high pressure through a series of die openings at the
end of the screw. At this point the material expands greatly
into a fluffy structured snack product due to the rapid e~pansion
of the entrapped steam. The product is then dried to remove
residual moisture and is often coated with fat. These snacks
have a rather uniform porous structure with larger inner voids,
and a flavor quite untypical of potato chips.
FIG lB is a cross-sectional elevation view showing
the internal structure typical of this group of potato snack
products.
(3) Several processes which have duplicated the
appearance of fresh potato chips generally form a thin sheet of
dough comprised chiefly of dehydrated potato solids and water.
The dough is cut or rolled into desired shapes, normally at
least partially dried, and then fried in a continuous operation ;
to produce an expanded snack product. The dough generally has a
solids range of about 60% to 70% by weight, and all the starch
in the dough is completely gelatinized before it is fried. The
pieces of partially dried dough material are generally more
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than 85% solids at the time they enter the frying medium.
Some of the products made by processes in this category
are described in U.S. Paten-t No. 3,539,356 to Benson, U.S.Patent
No. 3,297,~50 to Loska, U.S.Patent No. 3,~51,822 to Fast et al,
and U.S.Patent No. 3,59~,187 and Canadian Patent No. 871,648 to
Liepa~ Generally speaking, control of the processes in this
category in continuous operation is difficult and expensive,
because of the requirement for complex extrusion, die cutting,
and dehydration. The finished product is usually puffed to about
four times its original thickness upon frying, and is character-
ized by uniform structure through the product when the product
is viewed in cross-section. The texture and flavor of the fried
product are generally not typical of freshly fried potato chips,
and the products are difficult to store without breakage.
FIGS. lFthroughlI show cross-sectional elevation ~-;
views of the internal structure typical of this group of potato
snack products.
(4) In contrast to the large number of prior art snacks
produced by the methods in the preceding categories, attempts to
make a natural tasting potato snack by forming and directly
frying a relatively moist potato-based dough generally have been
unsuccessful. One product formerly sold in the Western United -
States under the trademark Viko Chips was made by combining -
dehydrated potatoes and wheat flour with minor amounts of rice
flour and corn flour to form a dough having a solids content of ;`
about 52% to 55~. The dough was extruded under high pressure
through a piston extruder and fried. The texture of the fried
product is relatively hard. There are no internal voids, as
there is relatively little expansion during frying. ~FIG. lD
is a cross-sectional elevation view showing the internal structure
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typical of this product.) Moreover, the flavor of the product
did not resemble potato chips due to the overpowering flavor of
the wheat flour.
In a si~ilar process disclosed in British Patent No.
1,109,930 owned by J.Bibby and Sons Ltd., potato solids are
mixed with potato starch to form a dough containing 30% to 40~
solids. The dough is extruded through a round opening and fried.
When viewed in cross-section, as shown in FIG 1~, the fried
product is seen to contain small voids filled with fat surrounded
by a very thin surface skin. Essentially no expansion occurs
when the product is fried. Moreover, considerable care must be
exercised in frying the product because the pieces tend to stick
together in the fryer.
SUMMARY OF THE INVENTION
: .
This invention provides an expanded potato snack having
a novel appearance or structure distinct from that of potato chips,
and which has a crisp texture and a potato flavour resembling that
of potato chips. An important advantage of the potato snack is
its capability of being manufactured in conventional equipment
~0 in a continuous mass production process at a relatively low cost.
Briefly, the potato snack is prepared by mixing cooked
potato solids with water and ungelatinized starch to form a dough
having between about 40% and about 50% solids by weight. The
dough is formed into pieces which are then fried immediately in
cooking oil to produce an expanded potato product. The potato ~`
dough at the time of frying contains a combination of ungelatin-
ized starch, preferably raw potato starch, potato solids,
including a quantity of intact potato cells, and a quantity of
free available gelatinized starch solids. Best results are
obtained when the ungelatinized starch i5 present in the range
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between about 30% to about 70% by weight of the total solids
present in the dou~h. ~he amount of free available gelatinized
starch in the dough is controlled so that the dough pieces
expand at least about 1.6 times their original dimension upon
S frying to ~orm a snack product having a cellular internal
structure encased in a dense exterior layer of substantially
reduced porosity.
In accordance with the present invention there is
provided a method for making a potato-based food snack product
from a dough comprlsing the steps of:
mixing the dough and extruding a piece from the dough
through an extruder die opening in preparation for frying the
dough piece, the mixing and extruding steps resulting in
essentially no gelatinization of the ungelatinlzed starch in
the dough, and the extruded dough being immediately thereafter
cut into a dough piece and then immediately immersed in hot ,-:
cooking oil so that at the time the dough is immersed in the ;. ;
cooking oil it comprises a mixture of (a) solids comprising
ungelatinized starch and gelatinized starch containing solids
provided essentially by cooked potato solids; (b) water; (c) in
which the solids are more than 40% and up to about 50% by
weight of the dough; and (d) in which the solids contain
between about 30% to about 70% ungelatinized starch by weight, :
with the balance being said gelatinized starch solids . ~ .:
containing sufficient available free gelatinized starch to ; .:
caUse the dough piece to expa~d between about 1.6 to 3.0
times when fried; ;~.
cooking the dough piece in hot cooking oil at a . ~::
sufficiently h.igh temperature and for a long enough period of
time to cause the dough piece to expand to a thickness of
between about 1.6 and about 3.0 times that of the extruder
die opening to form a finiShed fried snack product; and
thereafter removing the fried potato snack from the o.il.
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Products such as those manufactured by the processes
grouped as categories (1), (2~, and (33 above expand more than
about three times their original thickness. They generally have
a lighter bulk density than the products of this invention, and
are generally characterized by a softer, less crunchy texture.
This invention is grouped with the processes of category
(4) above. The dough prepared in accordance with this invention
has a potato solids content which is generally lower than the
dough mixtures characteristic of the prior art in this and the
other categories, yet it is capable of producing a snack
product having a typical potato chip flavor, wi~hout excessive
coloration or fat absorption, by directly frying the sub-divided -~
pieces of dough. By operating in the range of 40% to 50%
solids, the dough can be handled in many types of standard snack
forming equipment readily available and well known in the
industry. This simplifies the production so that the product
can be mass produced at a relatively low cost.
In addition to the above advantages, the process of
this invention produce~ a fried product having a particular
structure and texture. The finished product has a relatively
porous internal structure ~ncased in a continuous relatively
dense exterior surface layer of fried potato solids. The
structure of the outer surface layer of the finished product
is very similar to the s~ructure of a fresh potato chip. Thus,
the product closely resembles two overlying thin potato chips
joined by a porous internal structure of expanded potato solids.
The exterior laysr of the product shatters when chewed to provide
a crunchy sensation which is unlike any expanded potato product
produced by the prior art~ Thé release of pota*o flavour from
,the snack when chewed is similar to that o fresh potato chips
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because of the similarity between potato chips and the outer t
layer of the present snack. The inner porous structure can
be controlled to modify the texture of the product. For
example, a completely dense product (produced by a solids
content outside the 40% to 50g range) is hard and horny, and
its interior is characterized by overbrowning. Conversely,
the dense outer layer of the present snack product separates
slightly when fried, and entraps water vapor which produces the
porous inner structure which does not become overcooked by the ..
10. hot cooking oil. Thus, overbrowning does not occur, and the snack
maintains the desired fresh potato chip flavor. ~ -
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. lA through lI are cross-sectional elevation view~
showing the internal structure of typical prior art potato :~
snack products;
FIG. 2 is a cross-sectional elevation view showing ~ : .
the internal structure of a fried po~ato snack made by the .
process of this invention from a cylindrical shaped dough
piece; : .-
FIGS. 3 and 4 are cross-sectional elevation views of
fried potato snacks made by the process of this invention from
different strip-like dough pieces; : -:
FIG. 5 is a cross-sectional elevation view showing a ~ .
fried potato snack made by the process of this invention from
a relatively narrow strip-like dough piece;
FIGS. 6A through 6E are cross-sectional elevation
views illustrating the effect on the internal structure of the
fried potato snack of this invention when the solids content
of the dough varies from 35~, 40~, 43%, 50~, to 55%
respectively; and
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FIG. 7 is a schematic block diagram illustrating a
method of using recovered potato starch in the process of this
invention.
D~TAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
This invention provides a snack product prepared by
mixing cooked potato solids with raw ungelatinized potato
starch, adding water to form a dough, extruding pieces from
the dough, and frying the pieces to form an expanded fried
potato snack. The composition of the potato-based dough at
the time of extrusion into the fryer is adjusted to control the
expansion of the dough during frying. In this manner, an
expanded potato snack having a distinct structure can be formed,
while concurrently insuring that the finished product has a
flavor and crisp texture resembling that of freshly fried
potato chips.
The degree of expansion of the potato-base`d dough of
this invention is controlled so that when the dough is fried,
it has an expansion ratio generally in the range of 1.6-to-1
to 3.0-to-1, i.e., it expands between 1.6 to 3.0 times its
original thickness~ The expansion ratio is calculated as the
thickness of the fried product divided by the original die
width. A fried product having an expansion ratio lower than
the minimum desired expansion ratio, i.e., 1.6-to-1, generally
is unacceptable because of its hard, horny condition. In some
instances a product having an expansion ratio greater than
3.0 is acceptable, as will be discussed in detail below. In
all cases the finished product has a structure characterized
generally by a porous interior structure encased in a continuous
dense exterior la~er of substantially reduced porosity. The
detailed structural and textural characteristics of the product
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will be described in detail below.
The expansion of an extrusion of potato-based dough is
controlled in accordance with this invention by maintaining
the solids content of the dough, prior to extrusion, between
about 40% and about 50% by weight, preferably between 42% and
48%, and within this level adjusting the quantity of available
free gelatinized starch in the mixture.
For example, when extruding a dough composed of 750
grams of fresh, mashed potatoes and 355 grams of potato starch
(41.6% solids) through a slot 36 mils (0.036 in.) high and one
inch wide, the dough does not have sufficient cohesion to be `
extruded into a coherent strip. With the addition of 5 grams
of pregelatinized potato starch, the dough adheres, but is
fairly crumbly during extrusion and after frying, and the
insufficient expansion of the dough during frying results in
an undesirably hard, horny product. Increasing the quantity
of pregelatinized starch to 40 grams results in excessive
puffing and expansion of the product due to the entrapment of
steam within ~he sealed surfaces of the snack piece during
frying. By adjusting the amount of pregelatinized starch
between 5 and 10 grams, optimum appearance and texture result.
The same results can be demonstrated without adding
previously gelatinized starch products. A normal fresh,
mashed potato such as described in the previous example contains
approximately 4~ ruptured cells. Even with all of the starch
from these cells being mixed uniformly through the dough, the
quantity of starch was insufficient to contain the proper
amount of steam bubbles. However, if the mixture of mashed
potatoes and potato starch is subjected to vigorous agitation,
the starch released from additionally ruptured pota~o cells
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provides the binding power to ~orm the necessary controlled
expansion of the dough strip during frying. If the agitation
is continued, excessive gelatinized starch is released through
the rupturing of additional potato cells, and the same unde-
sirable puffing condltion described above results.
When using dehydrated potatoes in this process, the
quantity of gelatinized free starch in the dough can be
adjusted by addition of previously gelatinized and dried
potato starch or other starches, or through the choice of
dehydrated potato ingredients having known quantities of free
gelatinized starch. By free gelatinized starch is meant
starch available as a binding agent and not contained in an
intact potato cell, whether originally present in one of the
potato ingredients used in this process or not.
The potato-based dough described in this invention
contains a quantity of raw ungelatinized starch. (By "raw
ungelatinized starch'l is meant the substantially pure granular
carbohydrate separated from the product with which it occurs
in nature. This is to be distinguished from flour, which
contains certain significant amounts of solids other than
starch.) The critical amount of ungelatiniæed starch present
in the dough is in the range of about 30% to about 70% by
weight based on the total dry solids present. As shown in
the examples below~ the content of ungelatinized starch in the
dough, based on the total dry solids present, varies from about
30% to about 50~ when the dough is made from dehydrated cooked
potatoes, such as potato flakes, potato granules, and mixtures
thereof. An ungelatinized starch content below about 30
produces undesirable scorching of the finished productO An
ungelatinized starch content above about 70% produces a signi-
ficant reduction in the potato flavor and expansion of the
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product and also increases fat absorption beyond the point where
a commercially acceptable product is produced. Microscopic
examination of the fried produc~s indicates that substantially
all of the ungelatinized starch i~ gelatinized during frying.
It appears that the available gelatinized starch in the dough
prior to frying controls the initial expansion as bubbles of
steam are formed immediately after the dough is immersed in ;
the hot frying medium. The gelatinization and eventual de-
hydration of the raw starch provides additional binding
material which limits expansion by forming a continuous
dense outer surface layer that entraps the inner bubbles, -
creating a porous internal structure and the desired crisp
texture of the fried product.
Four general forms of dehydrated potatoes which can be
considered for this process are (1) potato granules,
(2) normal potato flakes, (3) potato flour, and (4) diced
dehydrated potatoes.
(l). Potato granules are unicellular dehydrated
mashed potatoes in po~dered or granule form. This product
contains a relatively small quantity of free gelatinized starch
on a weight basis due to the method of manufacture (see
Potato Processing, edited by Talbot ~ Smith, 2d Ed., publ. by ;;
Avi). When deep fried potato snacks prepared hy the method
of this invention are made from potato granules, quantities
of pregelatinized starch or other dehydrated products con~aining
a higher proportion of free gelatinized starch must normally
be incorporated. Alternativel~, during reconstitution, mixing
or extrusion, the potato granules can be subjected to suffi-
cien~ shear to rupture enough potato granule c~lls to release
the required amount of potato starch~
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(2). Potato Flakes - During the manufacture of potato
flakes, a sheet of dehydrated potato cells, approximately 5
cells thick, is broken to reduce the bulk density of the
finished product prior to packaging. (See Potato Processing, `
previous reference, and U.S. Patent No. 2,780,552 to Willard
and Cording,) As the potato flakes are broken to sizes con-
venient for packa~ing, the potato cells at the peripheral
edges of the flakes are ruptured, permitting potato starch to
be released during reconstitution. The following table shows -~
the relationship between the screen size of potato flakes, the
ratio of the peripheral edge volume to the total volume, the
texture score and the blue value - a method of determination
of free starch.
TABLE ;
EFFECT OF FLAKE SIZE ON TEXTURE SCORE, AND BLUE VALUE
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Screen Size Avg. dia. Ratio,periph- Broken Texture Blue
(U.S. Std.) of Flakes eral edge vol. Cells Score Value
Inches to total vol. %
6-8 0.124 0.032 12.5 6.5 40
8-10 0.096 0.042 14.5 5.5 45
20 10-14 0.069 0.058 14.8 5.0 6
14-20 0.044 0.091 15.3 3.5 91
20-40 0.027 0.148 23.0 3.0 167 ~-~
40-60 0.011 0.365 31.4 1.25 395
-60 0.006 0.667 70.0 1.0 ~90 -
25 Texture Grade: 7 - excellent, mealy
5 - normal mashed potatoes
3 - sticky, cohesive, beyond normal
level of acceptability
1 - extremely sticky, rubbery,
30, pasty, glue-like.
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(See Potato Processing, previous reference). `~
Typical potato flakes prepared as an article of `
commerce have a random size as follows:
U.S. Standard Screen Sizes:
5 +4 mesh 0.6%
+10 40.4
~20 49-0%
+40 8.7%
-40 1.3% ;;`
These flakes contained 21% broken cells as measured -~
microscopically by the method of Reeve et al (Food Technology,
1959, No. 10, pages 574-577). When commercial potato flakes
are used as the base potato ingredient in the process of this
invention, it is not usually necessary to add pregelatinized
starch. If potato flakes of very small size, say through 40
mesh, having a larger percentage of broken cells and available
gelatinized starch are used as the raw material, the flakes
must be blended with other dehydrated products such as potato
granules of lower free starch content to reduce puffing during
frying.
(3). Potato flour is a drum-dried product similar to - -
potato flakes, except that the finished product has been ground
to pass through an 80 mesh screen. Essentially all of the ~ -
potato cells are ruptured, and the presence of the excessive
quantity of free gelatinized starch precludes the use of
potato flour by itself as a normal raw material for this
process. However, potato flour instead of pregelatinized ~--
starch can be combined with potato granules or fresh, mashed
potatoes to obtain the desired expansion during frying.
(4). Diced, dehydrated potatoes are frequently ground
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into a flour product as a ~ase ingredient for snack manufacture.
Use of such ground, dehydrated, diced products is feasible in
the process of this invention as long as the relationship of
the total ~ree, gelatinized starch is regulated to maintain
the expansion during frying within the limits previously stated.
The amount of free available gelatinized starch in
the dough at the time of frying is provided in a variety of
ways to produce the proper expansion, texture, and structural
appearance of the finished product. The amount of free
gela~inized starch in the dough can be adjusted by (1) the
selection of the ingredients in the dough, (2) the method
used to form the dough, (3) the type of extrusion used to
form the dough pieces which go into the fryer, or (4) com-
binations of these factors. The free starch content of
various ingredients to be used in the dough can vary. Rupture
of potato cells during mixing and extrusion can release
additional free starch. ~;
If an insufficient amount of free gelatinized starch
is available in the dough at the time of frying, insufficient
expansion of the finished product results in an undesirable
hard, horny product. If an excessive amount of free gelatinized
starch is available in the dough when it goes into the fryer,
excessive puffing and expansion of the product causes the
final product to separate and either break apart in the fryer~
or form a hollow, pillow-shaped, undesirable product. The
latter phenomenon is called "puffing" or "pillowing". The
proper amount of free gelatinized starch produces a crisp
expanded snack product having the structure and texture to be
described in greater detail below in conjunction with the -~
~;drawings.
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A determination of the correct amount of free
gelatinized starch must be made for each formulation of the
dough because of the many factors influencing the absorption
of such starches. The absorption, or cohesive power, of the
S gelatinized starch, whether added as a separate component,
or whether present as an adjunct of the cooked potatoes or
the dehydrated potato product used in the formulation, can be
modified by several factors. For example, during the manu-
facture of dehydrated mashed potatoes the texture of t~e
finished product is modified by the precooking and cooling
treatment (U.S. Patent No. 2,787,553 to Cording and Willard)
which greatly reduces the absorption of the gelatinized starch.
A second factor influencing the absorption of tne
available gelatinized potato starch present in the dough is ~ i
the incorporation of various starch-complexing emulsifiers
and other such ingr~dientsO For example, the u~e of mono-
glyceride emulsifiers such as glycerol monostearate at a level
of about 0.5% in the manufacture of potato flakes and potato
granules is standard for texture improvement of these products. -~
Such emulsifiers can be combined with the dehydrated products
used as the raw materials for the products described in this `;
invention, or can be added directly to the dough prior to
extrusion in order to offset an excess of gelatinized potato
starch, and thus reduce the tendency of the product to puff
excessively during frying.
It will readily be seen by one familiar with the art
that there are inPinite combinations of the various dehydrated `~
potato products, gelatinized or ungelatinized potato starch
treatments such as precooking and cooling used in the manufacture
of said products, and starch complexing ingredients which can
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be incorporated in the dough produced in accordance with the
invention described here to control the expansion of the dough
during frying.
Examples are provided below to show that the control
of the expansion during frying can readily be made in several
manners by one practicing this invention, thereby allowing a
wide variety of choices of raw materials not hitherto possible
in the selection of raw materials for the production of pre-
formed potato snacksO The examples also illustrate that the
optimum quantity of available gelatinized starch calculated
as a percentage of the total dry ingredients varies according
to the nature and absorption of the starch itself.
The color of the finished, fried product is controlled
by blending the basic potato ingredient, or mixture of ingre-
dients, with raw potato starch, or other nonbrowning ingre-
dients. Normally, the reducing and total sugar content of
dehydrated potato products, whether granules, flakes, flour or
dice, is substantially higher than the maximum sugar content
permissible in the direct frying of raw potatoes into snack
products, such as potato chips or shoe-string potatoes. It is
therefore necessary to reduce the overall reducing sugar content
so that the color of the finished product will resemble that
of potato chips. Normally, a mixture of about one-half dehy-
drated potato flakes or potato granules, and one-half standard
raw, ungelatinized potato starch gives an acceptable product
color. Use of substantially more raw pota~o starch reduces
the overall potato flavor to a marked degree, and if carried
to extreme can produce a less typical mouth feel or texture
of the finished product. Increasing the ratio of potato solids
to raw potato starch produces a more na~ural potato flavor
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within the limitation permitted by product color. Ingredients
known to inhibit browning of potatoes during frying, such as
sodium bisulfite, can be added to the dough but these products
if used in excess tend to hasten the production of free fatty
S acids and darkening of the frying medium. The frying medium,
normally a hydrogenated vegetable shortening, is preferably '
maintained at 340F, a~nd at this temperature the products will
fry to doneness in one ~o two minutes, normally 80 to 105
seconds~ Higher temperatures and shorter time will produce
products of greater crispness, darker color, and less oil
content. Frying at lower temperatures reduces color develop- `-
ment, but substantially increases the fat absorption of the
finished product.
Other features of the process will be evident from
the more detailed discussion of the following examples of
the process. ~ '
Dehydrated Potatoes ' ; -
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The quantity of dehydrated potatoes chosen for the '
process, and the inert starch, such as ungelatinized potato
starch, salt and seasoning as desired are mixed with an
appropriate amount of water to yield a solids content of the
dough between 40% and 50%, preferably between 42~ and 48%. -`
Stirring for one minute in a standard Hobart (Trade Mark) '
mixer fitted with a paddle at 60 rpm is satisfactory for ~' ' '
25 complete blending of these ingredients. Following this, a ~'
portion of the mixture is placed in an extruder, extruded ''
. .
and, at substantially the original moisture content, dropped '' ~'
direct into cookin~ fat and fried about 90 seconds. '
T~e potato based dough formed in this invention is
30 ;normally friable and free-flowing, as mixed, and somewhat '~''
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~53068
putty-like, but not excessively sticky after compression, and
can be Eormed or shaped in many types of standard food shaping
equipment. Breakage of potato cells during extrusion, and the
resulting release of gelatinized starch, alter the texture and
expansion of the fried product, which, if not controlled, could
cause excessive puffing. A piston type extruder is one pre-
ferred method of forming. Roller sheeting equipment commonly
used for macaroni products can be used if care is exercised
that excessive cell damage does not occur during extrusion of
the dough through the roller apertures. The use of this type
extruder permits the continuous mixing of dry ingredients,
water and seasonings in one single step along with the
extrusion, thereby providing considerable economy of operation.
EXAMPLE 1
The following ingrediants were combined and blended
in a 5 quart Hobart (Trade Mark) mixer using a paddle, turning
at low speed for one minute.
Ingredients --Grams
Standard potato flakes made
from Idaho Russet potatoes
having a screen analysis of
1.5% on 4 mesh (U.S. Standard);
34% on 10; 41.B~ on 40; and
8.4% through 40 mesh 150
Potato starch, standard,
unmodified, ungelatinized -150
Salt 7
During an additional one minute of mixing, 347 ml. of
water at room temperature was added.
The mixing was continued at the same low spéed for a
third additional minute to insure uniform moistening of all
componentsO
3~ This mixture contained approximately 42O8~ solids,
and in this state was friable, but could be shaped into a
-- 19 --
.. . . ; . ~:
. ~
~53~6~
desired shape by application of pressure such as by squeezing
into the shape of a ball with the hand. The mixture was then
introduced into the cylinder of a piston extruder. By the
application of force from a screw, the piston forced the
potato mixture through a die opening 1 inch wide and 36 mil.
thick. The extruded dough was smooth and uniform and was cut
with a knife into pieces approximately 2 inches long. The
pieces fell into a standard laboratory fryer, containing hydro-
genated vegetable oil maintained at 340F where they were fried
with gentle agita~ion for about 90 seconds. At this time they
were removed, salted, and found to have a pleasing potato
flavor re embling potato chips and a desirable crisp but not
hard or brittle texture. The pieces had a slightly curled,
attractive appearance and were fully strong enough for dipping
in typical flavored dip mixes.
Ten such pieces were broken along a straight edge,
measured and were found to have an average thickness of 75
mils. giving a ratio of thickness to the original extrusion
thickness of 2-to-1. This is the method of determin~ng
20 Nexpansion ratio" in subsequent examples. The potato flakes ~-
used in this test were examined microscopically using the
method of Reeve et al and found to have 21~ broken cells.
The quantity of free gelatinized starch contributed by the
potato flakes were calculated by multiplying the dry weight
of flakes by 0.21 (the percentage of broken cells) and by
0.72 (the percentage of starch in the flakes). This quantit~
of free gelatinized starch, 20~8 grams, represented 7.6% of
the total dry solids in the dough~ This calculation and
others to follow assumes all of the starch in a broken cell
as a~ailable starch for binding purposes. The amount of
- 20 -
l0s3a~s
ungelatinized potato starch in the dough is about 47% by
weight based on the total dry solids presentO
EXAMPLE 2
The mixture of Example 1 was extruded through the
same aperture set at 30 mil. clearance. The finished
product averaged 67 mils. in thickness giving an expansion
ratio of 2.2, and was more tender than the product of Example
1 and somewhat more fragile.
EXAMPLE 3
The mixture of Example 1 was extruded through an
opening of 42 mils. yielding a product with an average thickness
of 89 mils. with an expansion ratio of 2.1, and with a slightly
firmer texture.
EXAMPLE 4
:
To the same mixture of dry ingredients used in
Example 1, was added 493 mls~ of water at room temperature
giving a solids content of 35~ in the mixture. This dough
was too wet and not cohesive enough to be extruded into a
smooth, flat shape. Small particles which were fried
required three to four minutes for completion of frying
which resulted in excessive fat absorption, an oily, greasy
taste, and an unnatural texture somewhat resembling pie cxust.
EXAMPLE 5
~ , _
Using the same mixture of dry ingredients as in
Example 1, the quantity of water added was decreased gradually
to measure the effect on the eating quality and the expansion
ratio of the fried product. At a solids content of 45% in
the dough, whether extruded at 30, 36, or 42 mils. thick, the
expansion ratio remained at about 2.2 and ~he products were
30; fully acceptable. At a solids content of 50% the expansion
- 21
f - , :
9L6~53~61il
ratio at 30 mils. thickness was 1.9, and at 3~ mils. thick-
ness, was 2.2. The texture of these products, however,
became untypically hard, and the product texture resembled
a cracker or other baked product, rather than the typical
potato chips prepared from fresh potatoes.
EXAMPLE 6
A mixture of 200 grams potato flakes, 100 grams raw
potato starch, and 7 grams salt were combined with 275 mls.
of water as described in Example 1, to yield a solids content
of 47.5%. The quantity of ungelatinized potato starch i~
this dough was about 31% by weight based on the total dry
solids present in the dough. (The potato flakes had a solids
content of 92% by weight, and the potato starch had a solids
content of 86% by weight.) This product was extruded and
fried as described in Example 1 and expanded to 1.7 times the
original extrusion thickness. The surface of the fried product
was noticeably rougher and the color was somewhat darker than
the product of Example 1, but the overall quality was judged
excellent. The quantity of free gelatinized starch in this
dough calculated in the same manner as described in Example 1
was 27.8 grams or 10% of the total solidsO
EXAMPLE 7
.
Mix~ures of dry ingredients similar to those in
Example 1 were prepared in which potato granules were used to
gradually replace potato flakes in the mixtures of the
dehydrated potato ingredients. A mixture of 25 grams potato
granules, 125 grams potato flakes, 150 grams potato starch,
7 grams salt mixed with 347 mls. of water and e~truded and
fried as described in Example 1 produced a highly desirable
30~ product. When the quantity of potato granules was extended to
2Z
~O~i3~6~
100 grams, mixed with 50 grams of flakes, etc., the product
extruded nonuniformly and ragged edges were apparent. The
finished, fried product had a greasy, oily taste, and a low
expansion ratio of 1.4. An additional replacement of flakes
with pokato granules was tested. The product became completely
unworkable.
Microscopic examination of the commercial potato
granules used in this example showed 8% broken cells. When
using 25 grams of the granules in the formulation abo~e the
available gelatinized starch was 18.8 grams or 6.85% of the
total solids. When using 100 grams of granules, the available
free starch was reduced to 12.4 grams or only 4.52% of the total
solids, not enough to provide sufficient expansion of the
dough during frying.
EXAMPLE 8
The ingredients of Example 1 were again used to
prepare a sample from standard Idaho Russet potato flakes.
In this case, the potato flakes were separated into two size
fractions using U.S. Standard screens. Two identical mixtures
were prepared using in the first case those flakes which
passed over the 5 mesh screen and in the second case those
flakes which passed beneath the 16 mesh screen. The dough
produced from the more finely ground potato flakes was
noticeably more cohesive.
The product from the large flakes had a short
texture, was somewhat greasy flavored, had a rough appearance
and an expansion ration of 1.6. The product prepared from
the fine potato flakes expanded to an average of 1~9 and had
excellent texture and uniform appearance. The larger flakes -
3d contained 8.2~ broken cells which reduced the free starch
-- 23 --
" .... .
. . . ~ ~ . . ....... ... .
9L~S3(3~3
concentration in the final dough to 8.1 grams or 2.96~ of the
total solids. The 16 mesh flakes had 34~ broken cells which
gave 33.7 grams of free gelatinized starch or 12.3% of the
solids content of the dough.
S Raw Potatoes
.
Raw pot~toes are washed, peeled, trimmed and cut into
appropriate sizes in a conventional manner prior to cooking~
If desired, the tubers may be sliced to approximately one-half
inch thickness and subjected to the precooking and cooling
treatment previously described to modify the texture of the
dough resulting from the subsequent steps of the process.
Generally, it is sufficient to slice the potatoes to uniform
thickness and cook the slices in atmospheric steam for 25 to
35 minutes, depending on the variety of potatoes and the
solids content. The cooked potatoes are mashed by ricing
them through conventional equipment using apertures of 1/16
inch to 1/8 inch diameter, by forcing the cooked potatoes
through round bars spaced 1/8 inch apart, or by passing them
between~rotating rollers maintained at a distance of 50 to
75 mils. In any case, the mashed potatoes are allowed to cool
to a temperature below the gelatinization point of potato
starch, namely, below 140F. If desired, the cooling is
effected by passing cooling water through the mashing rolls,
by blowing cold air on the potatoes or by other means known
to the artO The cooled, mashed potatoes are mixed with the
required amount of standard ungelatinized potato starch and,
if desired, additional quantities of either pregelatinized
starch or a dehydrated product selected from the group des-
cribed previously having sufficient free gelatinized starch
30, to provide the cohesiveness required in the extrusion into
the product of this invention.
- 24 -
.: ''.
~53~
Alternatively, the mashed potatoes can be subjected
to a mixing, kneading treatment designed to rupture sufficient
quantities of the potato cells to provide the desired cohe-
siveness in the dough. The mashing and mixing to produce a
desired level of cell breakage can be accomplished either
before or after the cooling step previously described.
The cooled, mashed potatoes and dry ingredients are
blended to form a dough in a suitable planetary mixer or
continuous ribbon blender of standard design. At this point
the mixed dough is friable, but can he forced into any desired
shape by hand manipulation. The dough is extruded and then
fried in the same manner as described above in connection
with dehydrated potatoes.
The finished product has a full, rich potato flavor
and has a thickness approximately 1.6 to 3.0 times the thick-
ness of the extruded dough. The texture can be varied by
adjusting the height of the extruder slot, base potato
ingredients, and the solids content o~ the extruded dough to
produce products either f irmer or more tender than standaxd
potato chips or corn chips~ Savory ingredients such as
dehydrated onion powder or garlic, barbecue spaces and other
standard flavoring ingredients such as MSG, salt, etc., can
be applied either internally by mixing into the dough prior
to extrusion or by dusting on the finished product after
frying.
EXAMPLE 9
.... . : .
Russet Burbank potatoes were peeled, sliced into 1/2
inch thick slices, steamed for about 30 minutes, and riced
through a conventional kitchen ricer with 1/16 inch round holes.
30~ After cooling to room temperature (75F), 750 grams of the
rice~ potatoes (having a solids content of about 20% by weight) ~
.'
- 25 -
,. : . ,~
,, .~ ~' . ,.. , ~
;,;
~3(~68
were combined with 363 grams of regular ungelatinized potato
starch (having a solids content of 88% b~ weight) and 7 grams
of salt and mixed for one minute on low speed to completely
blend the ingredients. This material had an average solids
content of 42.5% by weight. The amount of ungelatinized
potato starch in the dough was a~out 67~ by weight of the total
dry solids present. The dough was extruded as described
previously, but the dough lacked sufficient cohesiveness to
adhere in a continuous strip. Several small filaments of fried
product were obtained which showed an expansion ratio of 1~3 and
an undesirably hard texture. A portion of the mixture was
examined microscopically and found to contain about ~% broken
potato cells. The percentage of free gelatinized star~h in the
dough was calculated as 0.94%.
EXAMP~E 10
_ ~ ~ .
The mixture of Example 9 was then agitated at high
speed for an additional 5 minutes. The character of the mash
remained loose and friable and microscopic examination revealed
4.4% broken potato cells. The mixing was then continued for
a total of 8.25 minutes at which point a rapid, noticeable
increase in CohesivenesS was observed and the mixer immediately
stopped. A portion of the dough was extruded through a 36 mil.
aperture and fried to produce a highly satisfactory snack product
with an expansion ratio of 2.5. Microscopic examination of this
dough indicated 13.8% by weight of the potato cells had been
rup~ured. At this stage the dough then contained 3.2~% by weight
of-free gelatinized starch based on the total solids.
,
; - 26
.. , . . ,. ~
, ,, ' , ~ ~
~(~53~
EXAMPLE 11
A final portion of the dough remaining from Example 10
was beaten for an additional 45 seconds at which point the
character of the dough changed to a very cohesive, bread-like
dough which when extruded and fried produced abnormally puffed,
pillowed products not resembling potato chips or other conventional
snack items. The expansion ratio of several of these was 4.7,
although most were in a completely rounded shape. Microscopic
examination of the dough indicated that 55~ by weight of the
potato cells were now ruptured, resulting in a 13.0% by weight
free gelatinized starch concentration of the solids in the
dough.
EXAMPLE 12
_
The following ingredients were combined and blended in
a 5 quart Hobart (Trade Mark) mixer using a paddle, turning at
low speed for one minute.
Ingredients Grams
Cooked, riced potatoes
prepared as described in
Example 1, cooled to 100F 375
Potato starch (regular
ungelatinized potato starch) 160
Pregelatinized, dried
potato starch 5
Potato flakes, ground to
pass an 80 mesh sieve 8
Salt 10 -~
No additional water was required in this mixture as
the moisture content of the original potatoes contributed
sufficient to result in an overall solids content in the
finished mixture of 42.9~. The mixing was continued on low
speed for three minutes to insure uniform distribution of
, - ' ~ ~ '
- 2 7 -
.. ,. . ., , .,; ',: ~ ~ :
, ~ ~.- . . .
~53~;7~3
all components. This mixture r yery similar to that of Example 1
in consistency, was extruded through a 36 mil. slot and fried
at 340F for one minute. The finished product had an expansion
ratio of 1.9, and a distinctive potato chip flavor identity.
Example 12 shows that the desired dough characteristics
can be obtained using mixtures of various potato ingredients
and that the free starch used for binding and adjusting texture
can be derived from fresh potatoes, plain pregelatinized starch
and ~inely ground, dehydrated potatoes in the same formulationO
It will be noted also that in products made from fresh
potatoes the actual quantity of free gelatinized starch on a
weight basis is less than in products made from dehydrated mashed
potatoes. For example, the dough used in Examples 1, 6, and 8
cq~ntain respectively 7.6%, 10~, and 12.3% free gelatinized
starch contributed by the broken potato flake cells. In these
products the starch had been retrograded during processing by
a precooking and cooling treatment. The presence of 0.5~ amylose
of the potato starch additionally reducing the absorption and,
in the case of this invention, required a relatively high level
of available free gelatinized starch to achieve the desired
expansion. In Example 10 a concentration of only 3.24~ of free
gelatinized starch derived from plain, cooked, riced potatoes
gave the desired expansion. In Example 12 where cooked, riced
potatoes containing 4% broken cells were combined with pre-
gelatinized potato starch and potato flakes the total quantity of
12 grams of available gelatinized st~rch represented 5.1% of ~he
total solids in the mixture~
- 28
~53~61~3
Onion-Flavored Rings
EXAMPLE 13
To make a simulated fried onion ring product, the
following dry ingredients were combined and blended in a ~obart
5 (Trade Mark) mixer using a paddle turning at low speed for one
minute.
Ingredients Grams
Standard Idaho Russet potato
flakes having a screen analysis
(U.S. Std.~ of 1.5~ on 4 mesh;
34~ on 10; 41.8% on 40; and 8.4%
through 40 mesh 125
Potato starch ~Std. unmodified
and ungelatinized) 175
Salt 7
Onion powder (dry) 15
Water
After the dry ingredients were mixed for one minute,
the water was added during an additional minute of mixing, and
mixing was continued at the same low speed for a third additional ~ -
minute to insure uniform wetting of all the ingredients.
The dough was extruded through an annular slot 1/16
inch wide, and cut into rings about 1/16 inch thick. The rings
were dropped into a standard laborator~ fryer containing hydro- -
genated vegetable oil at 330F, and fried with gentle agitation
for about three minutes. The final product expanded to simulate
the texture of a fried onion ring.
Replacing part of the regular ungelatinized potato
starch in Example 13 with pregelatinized potato starch in the
amount of 3 grams, 6 grams, 12 grams, and 24 frams of free
starch produced an improved product with each increase of the free
pregelatinized starch. In the final example in which 24 grams of
' ungelatinized starch were replaced by gelatinized starch, the
29
, - .. , . : : ... :. ,...... .-
~L053(~
final fried product was the most tender of the group and had
noticeably more fat absorption than the others which is desirable
in the case of simulated fried onion rings. At no time was there
any undesirable excess puffing noted such as occurred with the
flat extruded pieces when the level of free gelatinized starch
became too great.
EXAMPLE 14
.. . _ .. _ . ,
The following ingredients were blended exactly as
described in Example 13, extruded through a ring die and fried
10 for three minutes at 330F.
Ingredients Grams
Potato flakes 125
Regular potato starch 158
Pregelatinized potato starch 20
Fat (hydrogenated vegetable oil) 15
Salt 7
Onion powder 5
Onion flavoring 3
Water 440
This product had an expansion ratio of 2.1 and was one
of the best produced as an onion-flavored ring snack.
The same dough of Example 14 was extruded through the
standard flat die at 36 mils thickness and fried at 330F. All
of the flat samples puffed excessively, and were unacceptable -
a~ a simulated potato chip snack. This indicated the correct -
amount of free gelatinized starch or one shape, say an annular
ring, is not necessarily the right amount for another shape such
as a flat strip. Apparently there is more tendency for the sides
of flat strips to push apart than in the case of the more
compact ring shape.
- 30 -
~`
~3~6~
Position of Extruder
If straight strips are extruded vertically into the fat,
the finished strips are practically straight after frying. If,
however, the extruder is mounted to extrude the strips horizont-
ally or at a substantial angle to the vertical, the product afterfrying assumes a curved shape which is more desirable in simulat-
ing a potato chip. Preferably, the extruder is mounted to
extrude strips into the cooking fat at an angle of about 45
to the vertical. This imposes sufficient curvature on the
finished fried product and also allows multiple extrusions to
fall into the cooking fat without sticking ~ogether.
The foregoing examples show that the geometry of the
extrusion, whether a flat strip or an annular ring, must be taken
into consideration with respect to the amount of free gelatinized
starch presen~ to get a product within the extremes of a hard,
compact unpuffed one on one hand, and one which has expanded
excessively on the other. In any event, the examples disclosed
herein clearly demonstrate how to adjust the amount of free
gelatinized starch to produce, on frying, a texture that
simulates potato chips or onion-flavored rings.
Use of Emulsifiers in Dough Mix
A quantity of emulsifiers can be added to the dough
mixture prior to extrusion. The emulsifier improves lubrication
of the dough as it passes through the die, which prevents addit-
ional cells from being ruptured. This reduces the free starchcontent in the dough at the time of frying, and can prevent the
dough pieces from puffing when fried. Thus, the emulsifier
allows a dough of higher solids content to be used when compared
with the instance where no emulsifier is used.
- 31
~ ,~,....
~LOS3~6~
EXAMPLE 15
A commercial piston extruder manufactured by Heat and
Control, Inc, of South San Francisco, was used to manu~acture
snacks of this invention on a continuous basis. The products
were extruded through the four annular dies located in the
bottom plate of the 8-inch diameter cylinder containing the dough
which was forced under approximately 500 psi pressure. The outer
diameter of the annular shaped opening measured 0.625 inch, and
the thickness of the dough was 0.040 inch.
The combination of ingredients for extruding this
product on a continuous basis was as follows:
Ingredients Grams
Potato flakes 202
Potato granules 225
Raw potato starch 277
Salt 16.5
Pregelatinized potato starch 7.2
Water 615
2.6 grams of glycerol monostearate emulsifier was
added to the mixture prior to extrusion.
The dough had a solids content of 48% by weight of the
total solids and water present.
Because of the high extrusion rate used for economical
operation of this equipment, it was found best ~o increase the
solids content to 48~ and include the additional glycerol
monostearate as indicated above in the formulation to produce
a well shaped product and to reduce puffing of the product.
Under these conditions a product having excellent texture and
appearance was produced on a consistent basis. A rotating knife
cutter was used to cut the products to an average length of 7/16
- .. . .
~ ,
~0~i3~68
inch with a length variation of only 1/8 inch.
Use of Roller Forming Equipment
The process of forming the dough pieces in preparation
for frying can be carried out by roller forming. For example,
a cohesive dough is rolled into a thin sheet and cut to form a
narrow, elongated product similar to the shoestring snack pre-
pared from fresh potatoes. To avoid scorching the interior of
the narrow pieces, an expansion ratio as high as 4.5-to-1 has been
used, as shown in the following example. Products made ~rom
dough pieces wider than about lf4 inch puff excessively when
using the same formulation. Extrusion of the same dough through
a piston extruder would also result in an excessively puffed
product.
The shoestring product is a special illustration of the
lS control of expansion afforded by the invention in which a high
level of gelatinized starch is used in the dough to make the
relatively narrow, elongated strip of dough expand intentionally
to an expansion ratio of bet~een about 3 and 4.5-to-1. Products
wider than about 1/4 inch made by piston extrusion, roller
forming, or other means are limited to an expansion of about
3.0-to-1 maximum, as any greater amount of expansion results in
the sides of the product separating, producing a large internal
void.
EXAMPLE 16
A dough ~as prepared by mixing ingredients described
in Example 1. The dough was first rolled into a sheet of about
1/4 inch thickness using a hand operated pasta roller. The sheet
was then rolled by the controlled aperture stainless roller to a
thickness of about 0.036 inch. From this sheet of dough, strips
were then cut about 1/4 inch wide and 3 inches long.
1~3~68
(1) The products formed from the dough of Example 1
had a thickness of only 0.060 inch and an expansion ratio of
1.7-to-1. This product was too thin, slightly hard, and
extremely curled.
(2) Five grams of pregelatinized starch were added to
the dough. This product expanded to 0.067 inch, i.e., an
expansion ratio of 1.9-to-1, and had a satisfactory texture.
(3) Ten gra~s of pregelatinized starch were added to
the dough of Example 1, after which frying expanded the product
to 0.085 inch with good texture.
(4) The same dough as Example 1 was mixed at medium
speed during reconstitution for 5 minutes. At this point there
was a noticeable change in the character of the doùgh as it
changed from a friable damp mixture to a more cohesive, lumpy
material. This product was rolled, but and fried, expanded to
0.073 inch, i.e., an expansion ratio of 2.0-to-1, and yielded a
product of good flavor and texture.
E~AMPLE 17
Shoestring snacks were prepared as described in Example
16 from the following ingredients:
Ingredients Grams
Ground potato flakes (-20 mesh) 110
Potato granules 40 ~ `
Potato starch 150
Salt 7
Water 360
Preliminary experiments indicated that a greater degr~e
of cohesiveness was required in the dough, compared to piston
extrusion, to facilitate handling and cutting in the rollerc~ For
this reason a lot of Idaho Russet flakes ground to pass a 20 mesh
- 34 -
~ o53~
sieve, was used. The screen analysis of these 1akes was:
On 20 mesh 4.7%
On 48 mesh 16.7%
On 60 mesh 25.6%
Through 60 mesh 50.8
Products extruded in the range from 0.030 inch to
0.050 inch expanded to the range of 3.0 to about 4.1-to-1.
The texture and flavor of these products was nighly desirable.
Some separation of the product in the center was noted,
particularly with the thicker products. Because of the
narrow dimension, 1/4 inch, the product could not separate
completely into a puffed condition. The product was slightly
rounded on the flat 1/4 inch wide sides. About 40% of these ;
products were curled during handling and frying. It was
noted that the thicker products ha~ a less scorched flavor.
A sample of the product made from dough sheeted to 0.042 inch
thick was broken open, and it was noted that the interior
portion was not uniformly brown. The thicker product had a
brown exterior with a light colored interior, giving a product
with overall less scorched flavor, which was judged more
desirable by the panel.
The same dough was used in a piston ex~ruder ~o prod~ce
~ cylindrical produci wiih 5/8 inch diameter at a tnickness
of 0.0315 inch. The product expanded to 2.9 times this
oxiginal dimension, but the shape was not consistent, the
edges were ragged, and many of the pieces were puffed.
Another sample was extruded in the piston extruder
through a 1 inch wide by 0.036 inch wide rectanyular slit.
All products puffed, and absorbea excessive grease.
A portion of ~he same dough was rolled in the pasta
.
- 35 ~
~)S3~6~
roller to a thickness of between 0.030 inch and 0.036 inch,
and cut into rectangular oieces measuring 1 inch by 2 inches.
When fried under the same conditions, these products expanded
with a ratio of 2.9-to-1. Some puffing was noted, but not to
the same extent as to the pieces extruded through the piston
extruder.
EXAMPLE__18
A commercial corn chip double roll extruder was used
to make the snack product of this invention. A model TC-500
(Trade Mark) forming unit, ~ade by the J. C. Ford Company,
Monterey Park, California, was set a~ an opening of about
0.030 inch clearance. A quantity of 20 pounds of dry ingre-
dients was mixed with the appropriate amount of water in a 60
quart Hobart mixer, according to the following formulation:
Ingredients Grams
Potato flakes (unground) 125
Potato granules 25
Raw potato starch 150
Pregelatinizel p~tato starch 5
Water 365
The solids content of this dough mixture was 41.5% by
weight of the total solids and moistuxe in the dough.
This dough was in~roduced between the 4-inch diameter
rollers by a standard Masa feeder which uses a single screw
extruder to produce an extrusion o~ dough 13 inches wide,
approximately 1/2 inch thick. The extruded sheet of dough was
divided into rectangular shaped products, 1 inch by 1.5 inches,
by means of a metal die which pressed against the forward
rotating roller. Pieces of dough were conveyed by a standard
flat chain conveyor and later fried to produce an acceptable
- 36 -
~5306~ ~
snack product with an expansion ratio of about 3.0-to-1.
EX~'~PLE 19
.
A dough having the same composition as that of
Example 17 was also processed in the ~. C. Ford roller
extruder. This dough was quite sticky and so~e difficulty
was encountered in removing the dough from the rollers.
Several flat pieces were obtained, however, which when cut
into 1/4 inch wide sections and fried, yielded a shoestring
product having an expansion ratio of about 4.0-to-1 with
excellent texture and flavor.
Effects of Re lacing Potato Starch with Miscellaneous Ingredients
P . ...................................... .. _
Preferably, a pure raw starch, rather than a flour,
is used as the raw ungelatinized starch component of the
dough. The physical character of raw starch, especially raw
potato starch, imparts desirable texture and appearance to
the fried product, in addition to providing a binder which
limits expansion of the product beyond the point where
undesirable puffing would occur.
- 37 -
~.~353~68
EXAMPLE 20
... .
Experiments were conducted to observe the effect of
replacing the raw potato starch normally used in the potato
snack dough with various food starches and flours such as corn
starch, corn flour, wheat flour, wheat starch, tapioca starch
and rice flour.
A hand operated piston extruder was used, and the
extruded product was fried at 340F. All products were extruded
through a l-inch wide rectangular die set at 0.036 inch.
The baslc formulation used for these tests were as
follows:
Ingredients Grams
Potato flakes (standard) 125
Potato granules 25
Test ingredients 150
Pregelatinized potato starch 2
Salt 7
Water 330
Evaluation:
1. Puffing. Any piece showing definite puffing was
segregated. The total weight of puf`fed pieces was expressed as a
percentage of the total product.
2. Thickness. The non-puffed samples were broken
along the straightest axis possible. Three measurements along
this break were made with a thickness gauge and averaged.
3. Expansion Ratio. This ratio was determined by
dividing the average thickness of the product by the die
opening.
4. Fat Analysis. The amount of fat pickup by the product
was measured by Soxlet extraction at Hibbs Laboratory, Boise,
Idaho.
- 38 -
.
~053~6~
5. Color. Coloration was determined by comparison
with The Potato Chip Institute Chart (scale 1 through 9: no. 1
is lightest, practically white, no. 5 is average potato chip,
no. 7 is dark potato chip, still acceptable, no. 8 very dark
potato chip, generally not acceptable, no. 9, extremely dark).
6. Flavor Grade. Flavor was tested by an expert panel
(1 - excellent, 2 - good, 3 - fair, 4 - poor (not acceptable for
commercial use), 5 - very bad). Flavor grades are based on
overall desirability of the snack flavor related to other potato
snack products. Resemblance to the potato flavor of fresh
potato chips is the arbitrary standard.
7. Appearance Grade. Appearance of the product was
determined by a visual test by an expert panel. (1 - excellent,
5 - very bad, as above in paragraph 6).
8. Texture Grade. The testure of the product was
tested by tasting and finger-breaking using an expert panel.
Grades were the same as those in paragraphs 6 and 7 above.
The test results were as follows:
Test Corn Corn Wheat ~heat Tapioca Rice Potato
n~dient Starch Flour Flour Starch Starch Flour Starch
,. . . . .
20 EVPLUATIaN-
Puffing % 44 0 32 43 17 1 10
Avg. thickness 62 49 59 60 85 53 74
E~nsion ratio 1.72 1.36 1.64 1.67 2.36 1.46 2.06
Fat Analysis % 29.2 29.9 38.6 27.8 28.0 33.7 26.2
Color 5 8 5 7 5 7 5
Flavor Grade 3 4 3 3 2 4
Appearanoe Grade 3 5 4 4 1 4
Texture Grade 3 5 3 4 2 4 1 ;
'
.
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~L053~
The product made with potato starch received the highest
rating generally because of its excellent potato flavor,
uniformly good appearance and texture, and low fat absorption.
The product made with tapioca starch was the only other
product which approached commercial acceptability. Compared to
the potato starch product, however, it was inferior because of
its lower level of potato flavor. Potato starch and tapioca
starch have a high initial viscosity on gelatinization. It is
believed that this characteristic ability of the starches to
bind the water molecules tightly in the starch gel formed during
frying accounts for the superior structure, appearance, and
flavor of the finished product when these ingredients are
included in the formulation.
Products with corn flour and rice flour were similar,
having a low expansion, dark color, and high fat absorption.
In contrast, the product made with wheat flour was softer,
expanded slightly more, and had a fair texture and sweet distinc-
tive flavor, but did not resemble a potato chip. The product
made with wheat flour puffed objectionably, and had a mottled
appearance which would reduce its value as a snack product.
Products made with corn starch and wheat starch puffed
excessively, appeared grease-soaked, and had a bland flavorO
Structure of the Fried Product
The method of this invention produces an expanded
potato snack product having a particular structure. The structural
characteristics of the fried product obtained in accordance with
the method of this invention are understood best in the context
of a comparison with the internal structure of other prior art
potato snack products. Figures lA through lI show photographic
replicas of the internal structures of various prior art potato
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9~053~6~3
snack products. These products were broken across a straight
line to expose their internal structure which was then photo- -
graphed to give a final enlarged view at 50x to lOOx.
Figure lA shows the internal structure of a potato
S snack 10 made by the dry collet process in accordance with the
teachings of the Gerkens and Speiser patents referred to above.
This product is expanded by short immersion in hot cooking oil
to produce a highly expanded product having relatively large
pores 12 throughout the body of the product.
Figure lB shows a potato snack 14 made by dry extrusion
of potato ingredients and sold under the trademark Crispy Taters.
This product expands greatly in~to a fluffy snack product
characterized by a fibrous structure 16 which entraps relatively
large pores 18 present throughout the body of the product.
Figure lC shows a cross-section of a typical potato
chip 20 made by frying a freshly sliced potato in hot cooking
oil for 3 to 4 minutes. The product exhibits a generally uniform
structure of dehydrated potato cells in theix original natural
configuration.
Figure lD shows the internal structure of a potato
product 22 sold under the trademark Viko Chips. The product is
made by extrusion of a dough containing dehydrated potatoes and
wheat flour, com~ined with minor amounts of rice flour and corn ;
flour, with a solids content of about 55%. There is little
expansion of the product during frying so the internal structure
exhibits substantially no internal voids.
Figure lE shows a "potato straw" 24 made by the process
disclosed in the British patent to Bibby referred to above. In
this process potato solids derived either from freshly mashed
potatoes or dehydrated potatoas are mixed with a major quantity
,
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~5~6~
of potato starch to form a dough having between about 30~ to
40% solids. The dough is extruded through a round opening and
fried, and minimal expansion occurs during frying. Substantially
the entire interior of the product is filled with small voids 25
~illed with fat, with substantially no outer structure other than
a thin peripheral dehydrated surface skin.
Figures lF through lI illustrate prefabricated potato
chips made from high solids content dough mixtures in which the
solids range in about 60% to about 70% by weight. Figure lF
shows the internal structure of a product 26 made in accordance
with the process disclosed in the patent to Benson referred to
above. This product is characterized by relatively large exter-
nal voids 28.
Figure lG shows a cross-sectional view of a potato
snack product 30 made in accordance with the process disclosed
in the patent to Liepa referred to above. This product has a
relatively soft texture when compared with the crisp texture
characteristic of the products of the present invention.
Moreover, the Liepa product exhibits a relatively continuous
nonporous internal structure, with the exception of random
internal voids 32 produced by puffing of the product during
frying. Figure lH shows the internal structure of a potato snack
34 produced according to the process disclosed in the patent to
Loska referred to above. In this process a mixture of dehydrated
diced potatoes, ground into a fine flour, is mixed with
ungelatinized potato starch and water to form a dough having a
solids content of about 55~. The dough particles are then
gelatinized by passing them through a steam atmosphexe held a~ a
high enough temperature so that all the starch in the dough is
gelatini~ed. These separate dough particles are then de~ydrated
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68
. .,. ~, . .
and later fried to form the expanded structure illustrated in
Figure lH. The structure of this product exhibits a soft bite,
and randomly oriented pores 36 throughout its cross-sectional area.
Figure lI illustrates a cross-section of a product 38
made in accordance with the process described in the patent to
Fast et al referred to above. This product is made from a high
solids content (71.5% solids) mixture of dehydrated potatoes and
water which is gelatiniæed by the action of a single screw
extruder resulting in a formation of a pellet of dough-like
material which is cut, flattened between rollers, dried, and
later fried. The structure of the fried product has uniformly
distributed pores 40 throughout.
Figures 2 through 5 show the internal structure of
products made in accordance with the process of the present
invention. Figure 2 shows a portion of a snack 44 which is ;
prepared from a cylindrical shaped dough piece. Figures 3 and 4
show various views of snacks 46 and 48, respectively, prepared
by frying relatively flat dough strips. In each instance a
major portion of the product's cross-section exhibits an
internal layer 52 having a relatively continuous line of pores
54 sandwich~d between two relatively dense outer layers 56 which
are substantially nonporous. That is, the product is
characterized by a cellular interior similar to other totally
expanded snacks enclosed by a dense outer layer similar to
potato chips~
It has been found that the outer layer 56 of the finished
product has a relatively constant wall thickness independent of
how the piece was extruded or its degree of expansion. The wall
thickness is generally in the range of about 0.025 to about 0O037
inch, which is approximately one-third to two-thirds the thickness
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6~3
of a potato chip. Generally the preferred final total thickness
of the snack product is within the range of about 0.065 to 0.100
inch, for example, about 0.072 inch. The outer layers of 0.025
to 0.037 inch thickness are then approximately each one-third
of the total thickness of the snack piece, with the inner porous
layer occupying approximately the center one-third. The result
is a snack which captures the potato flavor of potato chips, but
which~has a unique texture and appearance, and produces a crunchy
sensation when chewed.
Aside from the advantage o~ a crisp texture, the
relatively dense outer layer of the snack provides other
unexpected advantages. Breakage is reduced during packaging and
shipment. The rate of water diffusion from a high humidity
atmosphere is slower than with open porous snacks. Thus, the
snack product of this invention has a longer shelf life under
equivalent conditions. Moreover, the smooth continuous outer
surface has a pleasant mouth feel, since it produces no sharp
edges or rough surfaces which are characteristic of many other
fabricated potato snacks.
EXAMPLE 21
The oute~ layers 56 of several types of potato snacks
made in accordance with this invention were measured to determi~e
the wall thickness. The following table shows the wall thickness,
respectively, of (1) relatively wide strips (measured at their
center), (2) relatively wide strips (measured at their edge),
(3) relatively wide strips which puffed, (4) cylindrical products
extruded through an annular opening in the extruder die,
(5) a cylindrical product which puffed, and (6) relatively narrow
strips (shoestring products). Wall thickness was measured by
separating each snack along the line defined by its porous
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~1~53~
interior, and measuring the thickness of the remaining dense
outer layer with a micrometer.
Overall Extmded Wall
~ ~ ess Thickness Expansion mickness
Product (in.) (in.) ~atio (in.)
(1) Wi~ Strips .094 .036 2.6 .028
(o~ter) .077 .036 2.1 .029
.086 .036 2.4 .032
S(2) Wide Strips .071 .036 2.0 .028
(edge) .067 - .036 1.9 .033
.067 .036 1.8 .033
(3) Wide Strips -- .036 -- .028
(puffed) -- .036 -- .028
(4) Cylinder .072 .035 2.1 .026
(normal) .070 .035 2.0 .030
.074 .035 2.1 .031
.068 .035 1.9 .034
(puffed) 035 ~~ .031
(6) Narrow Strips .101 .036 2.8 .037
.118 .036 3.3 .030
.090 .036 2.5 .027
..
Thus,'the finished product is characterized by a
relatively well-defined outer layer having a thickness in the
range of about 0.025 to about 0.037 inch, independent of ~he /'
method used to extrude the product prior to frying or the product's
degree of expansio~.
Figure 5 shows the internal structure of a shoestring
type product 58 cut from a strip of dough prepared in accordance
with the process of this invention. The dough piece was 0.036
inch thick and 1/4 inch wide and was expanded to approximately
4.0 times its original dimension. This product exhibits the
characteristic inner void structure with the outer dense layer.
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3~)68
EXAMPLE 22
Figures 6A through 6E illustrate how the solids content
of the dough significantly alters the appearance and structure
of the potato snack obtained in accordance with the method of
this invention. This analysis shows that the 40% to 50% solids
content of the dou~h is cri~ical in producing good expansion,
together with the novel structure characteristic of the present
potato snack product.
The products shown in Figurès 6A through 6E were
10 prepared by the following formulation:
IngredientsGrams
Potato flakes~10
(minus 20 mesh)
Potato granules40
Raw potato starch 120
Salt 7
These,ingredients were added to specific amounts of water
to producè five dough m,ixtures containing 35%, 40%, 43~, 50%, and
55% solids by weight. ~All of these products were extruded through
the same piston extruder fitted with the sama 5/8 inch outer
diameter die with a slit width of 0.035 inch. Representative
samples of each run were broken open and photographed '
photomicrographs to exhibit their internal structure shown in
Figures 6A through 6E. ,,
Figure 6A shows a snack 60 prepared from a dough having , '
35% solids. The dough was soft and the cylindrical structure ;
collapsed during frying. Furthermora, there was no separation
of the two sides of the snack product, and there wer,e substantially
no internal voids. ~ ,,
When the solids content was increased to 40%, a fried ~;
' product 62 typical of the products obtained by the process of
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this invention was produced. This product is shown in Figure 6G.
When the solids content of the dough was increased to
43%, a product 64 shown in Figure 6C was produced. This product
exhibited a greater expansion ratio than the product of Figure 6B,
the expansion ratio being about 2.3-to-1. The texture and
appearance of the product was judged superior to any other
produced during this experiment.
Figure 6D shows a snack product 66 produced from a
dough having a solids content of 50%. This product exhibited
the characteristic dense outer layers 68, but the product was
not expanded as much as the product of Figure 6C, and thereby
produced fewer and smaller internal voids 70. This product
did not ~xpand much in frying, and the texture also was notice-
ably tougher than the product shown in Figure 6C. The product
was borderline as far as a commercially acceptable snack product
iS concerned.
When the solids content of the dough was increased to
55% solids, a finished product 72 shown in Figure 6E was mis-
shapen on extrusion and did not expand into the typical shape
of the snacks made by this invention. There were few minute
voids 74 scattered throughout the internal layer of the product.
Fat Content
The fat content considered most desirable for a fried
potato snack product is in the range of about 25% to about 35%
by weight. A pota~o snack product having a higher fat content
than about 35% is greasy, and the excess fat tends to mask the
potato flavor of the snack product. A potato snack having a
lower fat content than about 25% generally is too hard and there-
fore difficult to chew.
.' ~ .
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EXAMPLE-23
_
The following table lists the results of an analysis of
fat absorption as a function of the moisture content in the dough
prior to frying. The solids content of the dough was varied as
in Example 23 above, and the fat content of each snack was
measured after the snack was removed from the fryer and drained.
Solids Content Fat Content
(%) ~
51.3
33.9
43 26.2
23.8
22.5
Thus, the 40% to 50% solids content of the dough is
critical in producing a finished product having the desired fat
content necessary to produce a commercially acceptable potato
snack.
Use o~ Recovered Potato Starch
The snack product of this invention can be made from
dehydrated potatoes or cooked mashed potatoes and ungelatinized
potato starch recovered from a potato chip slicing operation.
In this instance the potato starch is not dried, but is added
to the mashed potato ingredients after recovery from the potato
chip process.
Referring to Figure 7, a potato chip processing plant
90 includes a slice washer 92 in which large quantitites of raw
ungelatinized potato starch 94 accumulate. This starch is a
waste product and generally creates a disposal problem.
In the method shown in Figure 7, potato starch 94 is
removed periodically from the washer and fed to a slurry tank
,96 where it is reslurried in water. The potato starch slurry is
`.
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then fed to a U.S. 40 mesh sieve screen 98 to remove potato solid
particles. The starch which settles in the screening operation
is then fed to a filter 100 which filters the starch to remove
excess water, thereby producing a fairly clean, partially
dewatered, starch product.
The plant shown in ~igure 7, may also include a system
for using cooked fresh potatoes in the snack process in
conjunction with the recovered potato starch if desired.
Potatoes 102 are peeled at 104, and cooked and mashed at 106,
after which they can be used in the dough preparation according
to this invention. Additional economy can be afforded by thus
utilizing small potatoes unsuitable for the manufacture of
potato chips and which have no o~her economical use.
The purified damp staEch produced at filter 100,
together with the mashed potatoes produced at 106, are then fed
to a dough preparation station 108, either separately or together,
where they are added to water, pregelatinized starch, potato
flakes, and potato granules to form the potato-based dough of
this invention. The dough is then fed to an extruder 110 for
extruding dough pieces into a fryer 112 to produce the finished
product of this invention.
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~,o~ 8
EXAMPLE 24
Purified damp starch obtained by the recovery method
described above was added to water and potato solids to form a
dough having about 43% moisture by weight. The dough was pre-
pared from the following ingredients: i
Ingredients Grams
Potato flakes 125
Potato granules 25
Wet Starch (49~ solids) 270
Pregelatinized
potato starch 2
Salt 7
Water 227
After mixing for about 2 minutes in the standard manner,
the dough was extruded in the standard manner and an excellent
product resulted.
The product made by this method had an improved flavor
over standard products made with dry ungelatinized potato starch.
Moreover, it was found that the recovered wet starch
used in this experiment contained 0.25~ protein on a moisture ~ree
basis, whereas s~andard potato starch ordinarily is washed free o~ -
protein, and control samples of such potato starch were analyzed
to contain only about 0.18% to 0.20% protein. It is believed ~
that the improved flavor of the products made with recovered --`
potato starch results from the fact that such starch has not been - -
thoroughly purified, and contains more protein than other
non-starch potato solids.
Thus, the combination of this snack process with an
existing potato processing line in which small, otherise useless
raw potatoes are cooked and added to the potato mash along with
; potato starch recovered from the cutting operations reduces the
loss of valuable potato solids, reduces stream pollution, and adds
to the flavour of the finished snack product.
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