Note: Descriptions are shown in the official language in which they were submitted.
9'-~s
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L0ll ~'~T C0NT~NT P0'1'~T0 Ci~IPS
BAC~CGl~0UND 0]i1 THE IN~ENTION
1, F _ 3 of the Invention
This invention relates to potato chips. More
particularly, it relates to potatO chips having a low fat
content. This invention especially relates to low fat
content pOtatO chips prepare~ by microwave heating.
20 Description of the Prior Art
In the conventional production of potato chips,
raw or blanched potato slices are deep fat fried to yield
the ~inal edible potato chip. The effect of frying on the
potato slices is to reduce the water content (fresh potatoes
contain approximately 85~ moisture) with consequent oil
15 uptake and to produce surface color and crispness. The
finished potato chips contain from 30-45~ oil or fat based
on the total weight of the potato chip and less than 5~
moisture. (As used herein all percentages are expressed
in weight unless stated to the contrary and the term "fat"
20 is to be understood to include both edible fats and oils,)
~ This high fat content is undesirable for many
reasons, For example~ it increases the total caloric
content of the potato chip making such a produc~ objectionable
to persons wishing to lose weight or to avoid weight gain.
25 The deep fat frying process also shortens the shelf stability
of the potato chipo Moreover, the frying process is dif-
ficult to control and o~ten results in excessively cooked
potato chips. A low fat content chip cannot be made with
deep fat fryinæ processes and the fat content cannot be
3o controlled as ~at is absorbed throughout the frying
operation.
~ ~19~
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1 ~ot~to chips havLng a fat content below 30-4~
have been prepared heretofore. UO S. Patent No~ 3,402,049
of Mancuso et. al. discloses a method of producing potato
chips having an edible oil or ~at con~ent o~ from about
5 20 to about 307'. Deep ~at frying is not employed by
Mancuso et. al. to obtain this lower fat content. The raw
potato slices are soaked in an edible fat at a temperature
below the gelatinization temperature of potato starch,
removed from the ~at, drained and heated in an oven or by
10 forced air drying at temperatures of 225-350F until the
desired degree of browning is achieved.
Oil uptake is also reduced in a process dis-
closed in British patent 1,034,035 where reductions in oil
content of 10-20~ are obtained. Here, the potato slices
15 are removed ~rom the deep fat fryer when their ~ater
content is still relatively high (5-20%) and then dried
by a heating process without further oil uptake, The
heating completes the required water extraction and the
necessary degree of browning and may be achieved by a
20 combination of hot air drying followed by microwave heating.
The first drying stage is relatively slow and the second is
relatively fast. Oil uptake is reported as 10-20% less
than in the conventional ~rying process. Others have
reported that microwave drying of partially deep fried
25 potato chips resulted in oil contents of about 32-38~
compared to 38-44% for those which were finish ~ried in
the conventional manner (Davis & Smith~ "Microwave
Processing of Potato Chips" 72,86-88, Potato ChipPer
(Nov. 1965)),
Heating or drylng o~ potato chips has been
achieved hereto~ore,by a variety o~ procedures. Hot air
drying is disclosed in U. S. Patent No. 3,402,049 and
r.,~ 45
1 ~ritish Patent 1~03llJO35 (discussed above) as well as in
U. S. Patent rTo. 3,o44,880 of Bogyo et. al. while radiant
heat drying to remove water from potato chips is disclosed
in UO S~ Patent ~lo. 3,353,962 of Smith, Jr.
Microwave heating is a relatively ne~ procedure
employed in the production of potato chips. British
1,034,035 discloses microwave drying ~or the removal of
some of the water from partially deep fried potato chips.
U. S. 3,365,301 of Lipoma et. al. discloses the use
of microwave heating to supplement the cooking of potato
slicesO Here, raw potato slices are deep fried to the
desired oil content but short of any substantial color
change and then the desired moisture content and degree
of crispness is obtained by exposure of the partially
15 cooked chips to microwave energy This procedure of
partially frying the potato slices and completing the
process in a microwave oven,as well as the commercial use
of this procedure, is discussed in Talburt and Smith,
"Potato Processing", 287-290 (The Avi Publishing Company,
20 Inc. 1967).
The combination of a deep fat fryer and a
microwave oven for the cooking of foodstuffs is disclosed
in U0 S. Patent No. 2,997,566 to Pierce et. al~ The deep
fryer is provided with an external source of heating to
25 heat and meintain the cooking fat at temperature. The
microwave energy cooks the ~oodstuff while the cooking
fat browns the exterior of the foodstuff to provide the
desired surface finishing and sealing. It has been suggested
that this combination apparatus may provide very low fat
3o absorption (Copson, "Mlcrowave Heating", 375 (The Avi
Publishing Company, Inc. 1962)). Copson also suggests
the substitution of a non-toxic, flavorless resin such
as a silicone, for the cooking fat or oil in the combination
deep fat fryer-microwave oven to provide "fat-free" deep
r
3.~ S
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1 ~at f~rying. ~-iow~ver~ the elimination o~ the reservoir o~
liquid coo~ing medium within the microwave oven has not
been suggested by either Pierce et. alO or Copson.
Microwave heating is employed as one of the steps
5 in a process of producing dehydrated ~rench fried potatoes
disclosed in U. S. Patent No. 3,~81,028 to Capossela, Jr.
et al. Prior to deep fat frying, the potatoes are sub-
jected to micro~ave heating which causes a minimal water
loss o~ 2.5 - 3.0% but, more importantly, causes a degree
10 o~ gelatinization throughout the potato piece which is
critical in producing the dehydrated ~rench fried product.
However, although dehydration is e~fected in the deep
frying and a final heating stage,reducing the water content
more than 3~ by microwave heating prior to deep ~at frying
15 is said to produce an unduly hard and dry french fry
because Or excessive starch gelatinization.
Heretofore, neither low ~at potato chips nor
conventional potato chips have been produced by a process
which eliminates completely immersion frying of the potato
20 pieces and utilizes a single step o~ heating by microwaves
to remove water and produce a crispy product having the
uniform color and taste o~ deep ~ried potato chips.
It is an object of this invention to provide
potato chips by a process which eliminates deep ~at
25 frying~
It is another object of this invcntion to provide
potato chips having a fat content signi~icantly lower
than that obtained heretofore by commercial processes.
It is still another object o~ this invention to
30 provide potatO chips by a process which utilizes microwave
heating as the sule means o~ reducing the water content
o~ the potato piece to the required level and providing
the color, crispness and flavor o~ deep ~ried potato chips.
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1 SU~IARY OF T~l~ II~J~ !TION
In accordancc with the pr~serlt invention, it has
been ~`ound that a low fa~ potato chip can be prepared
in a mlcrowave oven without deep fat frying. More
5 particularl;~, -this invenlion is directed to a process of
preparin~ a potato product having a low fat content which
cornprises:
(a) coatinr~ raw potato slices with a quantity of
edible oil, said quantity being sufficient
to produce an added fat content of up to
about 20~o in the potato product,
(b) microwavc heating the coated potato
slices for a period of time sufficient
to produce a product havin3 substantiall~
the same flavor, color and crispness as
deep fat fried potato chi.ps and a fat
content of up to about 20~.
This invention is also directed to the po~ato
product produced by this process.
In addition, this invention relates to a potato
product comprising:
A slice of potato coated with a quantity of edible
oil, said quantity of edible oil being sufficient to pro-
duce in said product an added fat content of up to about
2520~ ~nd said coated slice havingJ been subjected to micro-
wave heating for a sufficient period of time to produce a
product having substantially the same flavor, color
and crispness as deep fat fried potato chips and an added
fat content of up to ahout 20~.
30DESCRIPI'ION OF THE PR]3FERRED EMBODIMENrl'S
The present invenlion rclates to low fat potato
chips. The potato product produced by the proc~ss of
l -~his inv n;ion has I fat cont~nt o-f 1~ss than about 20~
hich is lower than th~ 3o-l!5~o~ ra~ cor-~tenl oi conventional
deep ra~ friecl po~ato chips. It is also significantly
lower than those of I~Iancuso et al. as ~ell as those ~Ihich
5 are partially decp fried ancl then dried in a microllave
oven to obtain a fat content some 10-20~ less than the
conventional product. Not only is the fat content of` the
potato chips prepared by the process of the present inven-
tion significantly reduced but the caloric content o~ these
lO potato chips is also less than the conventional product.
~y coating the raw potato slices with edible oil and sub-
jecting the coated slices ~o microwave h~ating for a suf-
ficient period of time, a product is obtained which sur-
prisingly has the color, and appearance of conventional
15 potato chips as well as the crispness and flavor of the
conventional product but with a much lower fat content.
The reason why this process is able to produce a
product so surprisingly similar to conventionally produced
potato chips is not known. Since hot air oven processing
20 of edible oil coated slices of raw potato yields a poorly
textured and poorly flavored product~ it is thought that
the combination of e~ible oil coating and microwave heating
is essential to product the low fat product of this in.-
vention which is so similar to deep fat fried potato chips.
In practicing this invention, potatoes are washed,
peeled, sliced and water-washed as heretofore. Optionally,
the slices may be soaked in a dilute (e.g., O.l~) aqueous
solution of sodium meta bisulfite or tetr~butyl hydroquinone
for 15 - 60 minutes, followed by washing with cold water to
30remove residual quantities of the sulIite or the hydroquinotle.
The sulfite has been used heretofore as a bleaching agent
while the hydroquinone reacts with the sugar in the potato
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1 to avoid -the dark color such sugar of~en produces in the
f`inished potato chip.
Tne ~arieties of potatoes preferred for deep f`at
fried potato chips, i.e., Kennebec, Nordchip, Oncida,
5 Monona, Tobique and the like, may be employed in this
invention. Other varieties whose sugar conten-ts have made
them undesirable as "chipping" potatoes may ncnetheless be
employed satisfactorily in this invention. These poor
"chipping" potatoes have high reducing sugar contents,
10 0-5 - l.O~o glucose and higher. This sugar reacts during
frying to form an-undesirable dark brown color in the
finished potato chip. As the moisture decreases below about
6-8~o during deep fat frying, the rate of browning is
accelerated if reducing sugars are present in the potato
15 and an unsatisfactory product is often produced because of
the dark brown color. However, in the microwave heating
process of this invention, excessive brownin~ is not obtained
even with the high glucose varieties. Thus, such "non-
chipping" varieties as Irish Cobblers and the like may be
20 usefully employed in ~racticing this invention.
After the potato slices are water washed, the
excess water is removed by, for example, blotting dry with
paper towelin~ or draining and exposurc to a stream of
warm air. All of the slices are then coated with a layer
25 of edible oil before being sub~ected to microwave heating.
The oil is most easily applied in the form o~ a liquid.
The appl:;cation may be accornplished, f`or example, by dipping
the slice in a quantity of edible o:;l or by spraying edibLe
oil onto all surf`aces of the pot~to slice. ~dditionally,
30an oil coating may also be applied by soaking the raw
potato slices in oil for an e~tended period of,
for example~5-30 minutes, followed by draining of the
l coated slices to remove excess ~uantities of oil. Coating
the slices by dipping or sprayin~ usually prod.uces a
potato chip with a lower fat, content than is obtained
by the soaking technique and these methods may be pre-
5 ferred. However, the soaking technique does proclucea satisfactory product and a potato chip having a f'at
content wi~hin the limits described herein can be produced
by proper selection o~ the soaking time followed by a
period of draining to remove e}~cess oil.
l~hichever procedure is employed, the quantity
of oil applied to-the potato slices must be such that
after microwave heatin~ to produce a p.otato chip of
acceptable qUality~the added fat content of the finished
product is less than about 207~. Although a potato chip
15 product can be produced by the process of the present
invention with edible oil coatings which produce an added
fat content of as low as 15~, the eating qualities of this
product are not as satisfactory as those whose added fat
content is about 5-lO~. A practical lower limit of the
20 quantity of edible oil with which the potato slices are
coated is an amount which will yield a potato product
having an added fat content of about 5%. Therefore the
product of this invention has an added fat content of at
least about 5 up to about 20%, preferably from about 12
25 to about 157~.
The term edible oil as used herein includes edible
fats. Specific examples of useful edible oils include
olive oil, peanut oil, corn oil~ coconut oil, refined
cottonseed oil, soybean oil, sesame oil and the li~e as
3well as mixtures thereof'.
The oil coated raw potato slices are processed
- into low fat potato chips by microwave heating. This is
_9
1 acco~plished by placing the coated slices in a microwave
oven and su~ec~ing them to microwave heating. Microwave
ovens ~hich are co1~mercially available for home as well as
industrial use may be employed. These ovens oper~te at
5 a frequenc~ oI hundreds and thousands of mer~ahertz. Those
operating at 910-915 ~ -z have proven satisfactory in this
invention, al~hough units operatinc~ in the 2400-2500
~z range can also be used. Microwave heating times of
about 5-15 minutes, usually about 6-9 minutes normally,
10 product a satisfactory potato chip. The proper period of
time can be readily determined by one skilled in this art
from several test runs. Such variables as the variety of
potato, the ~hickness of the individual potato slices, the
nature of the oil employed, and the quantity of the oil
15 coating w~ll effect the time required for the microwave
heating to dehydrate the slices and provide the required
degree of crispness and light brown color.
~ lthough the practice of this invention usually
involves the preparation of potato chips from raw potato
20 slices, it may also be practiced by lyophilized potato
slices. ~fter the raw potato slices are prepared and,
optional].y, subjected to a sodium meta bisulfite treatment
as described hereinbefore~ they are freeze dried to reduce
their water content. ~ollowing this, the slices are
25 processed by the practice of the sub~ect invention in a
fashion similar to 1;hat described for the raw potato slices.
The product produced by microwave heating of the
oil coated potato slices has the appearance of deep fried
potato chips and posscsses the taste and cr:Lspness of the
30 more conventional product.
The potato chips prepared by the process of this
- invention are a low ~`at, low caloric product. Their fat
~L~C~ 5
-10-
1 content is less than about 20~, preferably frorn about 12
to about 157~. The lower limit of added ~at content is
about 5~. The caloric level of these potato chips is
substantially less than the caloric Icontent of deep fried
5 potato chips. The moisture content of the potato chips of
this invention is similar to that of the conventionally
prepared proàuct~ i.e., less than about 5~, usually about
2-3~.
The following examples illustrate embodiments of
10 this invention.
EXAMPLE I
Fresh, raw potatoes were peeled, sliced, water
washed and dried. The slices were soaked in Crisco*brand
vegetable oil for 15 minutes and then were placed on a
15 glass tray and subjected to microwave heating in a house-
hold Toshiba electronic oven for 6 minutes (the slices were
turned over after 3 minutes of heating). The product re-
moved from the oven had the appearance of deep fried
potato chips. These chips had good flavor, texture and
20 organoleptic oil level. The fat content of these potato
chips was 15%.
.
3o
* Trade Mark
19~S
1 EX~MPLEJ II
A quantit;y of fresh, raw Kennebec potatoes were
peeled, Sliced to a thickness of 1.3 mm, water ~ashed ~nd
dried. The sliced potatoes were divided into three groups
5 and processed as follows;
Group I - The slices were submerged in Crisco
brand vegetable oil and immediately drained i~ a strainer.
The slices were then placed vertically between 2 1/2" pegs
on a 1/2" ridged circular sheet composed of polypropylene
10 and placed in a Sharp ~lodel No. 8200, carousel
type microwave oven and subjected to microwave heating for
12 minutes.
Group II - The slices were coated with oil in the
fashion of the Group I slices and were then placed in a
15 conventional household oven until the slices were light
brown in color.
Group III - The slices were not coated with oil
but were subject to microwave heating in the fashion of the
Group I slices.
The Group I potato chips were superior in appear-
ance and in eating quality to the Group II and Group III
products. The Group I chips had a fat content of 12%.
They also had good flavor and texture. The Group II
potato slices yielded a poorly textured and poorly flavored
25 product. The Group III slices which contained no oil
produced a yery dry tasting chip with a paper-like texture.
3o
* Trade Mark
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