Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Inventor: Robert A. Hibbs, Ph.D.
and Wayne B. Durfey
Attorney Docket No.: 8709
PROCESS FOR PREPARING SLICED POTATO PRODUCTS
FIELD OF THE INVENTION
This invention relates to potato processing and,
more specifically, relates to a process for preparing
sliced potato products that results in the preservation
5of the fresh-cut characteristics of the sliced potato
products for a minimum of 45 days without additives or
preservatives.
BACKGROUND OF THE INVENTION
10Originally, commercially prepared potato products
such as French fries and homefries were processed at the
restaurant level. The characteristics of deep-fried
potato pieces were generally considered superior to
other potatoes prepared by different commercial process-
15es. Typically, processing was minimal and the result
was a finished product having a varied color, low sol-
ids, and natural flavor.
As consumer demand grew, however, the in-house
process became more and more impractical. Problems
20associated with offal (waste products, i.e. peels, trim)
disposal, uniform quality of the raw product, in-house
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storage space, and adequate supply forced large users to
a processed frozen substitute.
The current popularity of processed frozen potato
products is more the result of commercial feasibility
than it is the result of preferred product quality char-
acteristics. In fact, frozen potato processors have
been unsuccessful in their attempts over the years to
duplicate "fresh cut" potato characteristics. One draw-
back with French fries from processed frozen potatoes is
that the texture changes rapidly after reheating of the
frozen product. Just after reheating, the product is
crisp and shows good texture but, on cooling, becomes
limp and soggy with a greasy taste.
In addition to frozen processors who generally
distribute nationally, most major cities have local
suppliers of fresh-cut potato products. These proces-
sors have thrived over the years because they offered
lower cost and their products more closely resembled
fresh-cut potatoes. But these processors lacked unifor-
mity across the country, and chain restaurants were
unable to use the product since they require uniform
cost control and quality.
Additionally, during the past decade, certain pre-
servatives used by local fresh suppliers have been found
to be harmful to humans. In the absence of suitable
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preservative alternatives, these suppliers will be con-
fronted with further debilitating problems.
Recently, there has been a renewed interest in in-
house processing of whole potatoes. Restaurants that
5process fresh French fries advertise this fact to their
consumers who have responded favorably. There is every
indication that the characteristics of fresh-cut French
fries are experiencing renewed preference by a growing
number of today's consumers.
10Certain prior art patents for potato products pro-
duced for refrigerated storage (e.g. United States Pat-
ent No. 4,579,743 issued 04/01/86 by Hullah) cite the
general preference for freshly prepared products. The
popularity of frozen potato products, however, has been
15due to increased dining out frequencies and chain res-
taurant demands for cost control and quality uniformity.
As is well known in the art, however, the quality
of frozen potato products is adversely affected by nu-
merous processing steps that achieve high finished sol-
20ids and color uniformity at the e~r~e of potato fla-
vor. In fact, with some prior art processes, starch and
sugar have been so completely removed that the product,
as consumed, takes on an oil and seasonings flavor more
dominant than the potato flavor. Freezing also adverse-
25ly affects the texture of potato pieces due to the rup-
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turing of cells and the releasing of moisture and
starch.
One alternative to frozen packaging and storage is
controlled atmosphere packaging. In general, with con-
trolled atmosphere packaging, the potatoes are washed
and sliced, blanched to inactivate enzymes, cooked, and
vacuum packaged under a controlled atmosphere. In gen-
eral, however, due to processing and quality problems,
this technology has not received widespread commercial
acceptance.
A review of processes utilizing controlled
atmosphere packaging, for example, United States Patent
No. 4,957,761 issued 09/18/90 by Hale ('761), reflects
the widespread use of hot water (up to 190F) for pro-
longed periods of time (10 to 20 minutes) as a means of
controlling color. This processing step adversely af-
fects the solids content and flavor of the finished
product. While the use of hot water may indeed create a
white crust on the potato strip, it effectively reduces
the starch and sugar to achieve this whiteness.
A water blanching step makes the outer surfaces of
the potatoes even whiter and removes even more solids.
The solids are leached from the potatoes into the
blanching water, removing some of the natural flavor.
It will also remove some nutrients and, especially,
water-soluble vitamins.
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It is apparent that the above cited processes,
including the Hullah process, fail to achieve the flavor
and texture of a fresh-made potato product. The present
invention, on the other hand, is directed to a process
which effectively retains the natural color and texture,
i.e. lower solids, associated with fresh-cut potatoes.
In addition, the manufacturing cost of the process of
the invention will be reduced compared to other process-
es that increase solids in the potato strips.
Moreover, the product of the present invention, as
packed, will contain less than half the oil normally
associated with frozen fries; and, while oil uptake in
finish frying must be controlled, it offers justifiable
health claims.
It is thus a specific object of this invention to
provide a sliced potato product with minimum processing
steps which, when French fried, has the taste, texture,
and color variation normally associated with fresh-cut
potatoes.
It is another objective of this invention to pro-
vide a sliced potato product that can be stored for an
adequate period of time between process and consumption
without noticeable deterioration in color, texture,
taste, or healthful characteristics, including microbio-
logical quality.
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It is an object of this invention to provide a
sliced potato product having no artificial preserva-
tives.
It is an object of this invention to eliminate the
use of hot water or steam as a blanch or cooking agent
which results in a reduction in natural sugar or starch.
It is an object of this invention to use an oil
blanch as a sterilizing process rather than as a cooking
process.
It is an object of this invention to allow for some
textural enhancement associated with air drying, if pre-
ferred, in specific applications of the invention. It
is recognized, however, that air drying creates a higher
solid content and some loss of flavor.
It is an object of this invention to minimize oil
uptake in a finished, processed potato product to about
5%.
It is another object of this invention to provide
consumers with a better tasting, more healthful French
fry.
SUMMARY OF THE INVENTION
In accordance with the present invention, a method
for preparing sliced potato products is provided. The
method of the invention simply stated comprises blanch-
ing and sterilizing sliced potatoes in hot oil and then
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cooling and packaging the potatoes in a controlled atmo-
sphere that includes CO2 gas. The process subjects the
potatoes to a minimal amount of handling so that natural
texture of potatoes is maintained. Moreover, the solids
content and color of the potatoes is maintained by the
use of a hot oil blanch rather than a water blanch as
taught by the prior art.
More specifically, the method of the invention
includes the steps of:
preparing fresh potatoes by cutting, washing,
and dewatering;
blanching and sterilizing the sliced potatoes
in hot oil;
chilling the sliced potatoes;
packaging the sliced potatoes in a package
having an inert gas atmosphere that includes
2 0 C2; and
storing the package of sliced potatoes at a
cool temperature until ready for use.
2 5 Potatoes processed in accordance with the invention have a shelf life of about 6 to 10 weeks.
Other objects, advantages, and capabilities of the
present invention will become more apparent as the de-
scription proceeds.
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BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a flow diagram of a process for prepar-
ing a sliced potato product in accordance with the in-
vention.
DETATTlT~n DESCRIPTION OF THE INVENTION
Referring now to Figure 1, a process for preparing
sliced potato products in accordance with the present
invention is shown. The process broadly stated includes
the steps of:
preparing potatoes for processing including
cutting, washing, and dewatering, step 10;
blanching and sterilizing the cut potatoes in
hot oil, step 12;
draining excess oil, step 14;
chilling the potatoes, step 16; and
packaging the potatoes in a package having an
inert gas atmosphere that includes CO2, step
18.
A critical step of the process is step 12 in which
blanching and sterilizing of the cut potatoes is accom-
plished in hot oil. The process parameters of the oil
blanch step are closely controlled to insure that the
product has to the largest extent possible the texture,
color, and solids content of natural potatoes. This is
done by oil blanching at a relatively high temperature
for a relatively short period of time.
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In general, the initial processing step, step 10,
is accomplished by techniques that are known in that
art. The raw product may be taken as field-run potatoes
(unsorted) from freshly harvested or modern storage
stocks without special treatment. They are preferably
of the Russet variety and, preferably, warmed prior to
storage removal. (This is a reasonably normal storage
activity that converts sugar-to-starch and helps to con-
trol wide changes in color that is a natural process
within the tubers.)
Potatoes enter the factory and are washed and may
be peeled or, alternately, may remain unpeeled. Trim-
ming and defect removal are achieved by normal factory
processes, and the potatoes are cut by the normal meth-
ods. As an example, a suitable slicer, such as a model
CC Urschel slicer manufactured by Urschel Manufacturing
Company, Valparaiso, Indiana, may be used to cut the
potatoes into a desired size and shape. Slivers, and
short pieces are removed by conventional processes for
use in other by-products.
As an example, cold chlorinated water may be used
to wash and transport the cut potatoes. Prior to
blanching and sterilizing, the cut potatoes must be
dewatered by known techniques, such as conveying on an
open mesh conveyor. Air drying may also optionally be
used to enhance the texture and crispness. The time and
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conditions of air drying must be closely controlled to
prevent moisture loss from the potatoes.
From this point, the normal potato process changes
dramatically from prior art processes, i.e. hot water
blanching and hot water exposure are completely by-
passed. As is known in the art, blanching heats the
potato tissue throughout at time and temperature condi-
tions high enough to inactivate the enzymes, which would
otherwise cause oxidative darkening of the potato tis-
sue, but not sufficient to soften the tissue enough for
normal consumption. Normal blanching conditions range
from about 3 to about 6 minutes at water temperatures of
about 170F to 190F (77C to 88C). As previously ex-
plained, a problem with water blanching is that it may
adversely affect the texture, solids content, and color
of the potato. With the process of the invention, the
cut potatoes are subjected to blanching and sterilizing
in hot oil, step 12.
The oil blanch time is relatively short to prevent
overprocessing of the potatoes as previously described.
As an example, a conveyor belt transport through an oil
bath may be used as a blanching method. The fry or
blanch time may be varied depending on potato thickness
and the depth of the potatoes on the belt. By way of
illustration, the blanch time may be from about 1.5
minutes to about 3 minutes. The oil temperature may be
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about 360F (182C), and oil uptake may be targeted at
about 5%.
The dwell time between blanching, step 12, and
chilling, step 16, is used to drain excess oil. This
may also be done by conveying with an open mesh convey-
or. Chill time and temperature are also critical param-
eters of the process but can be achieved by various
mechanical refrigeration systems known in the art, i.e.
liquid nitrogen or CO2 refrigeration. The exiting prod-
uct surface temperature is preferably between 28F and
32F (-2C to 0C)
After cooling, the cut potatoes are ready for pack-
aging. The product is promptly packed in modified atmo-
sphere packaging, step 18, using suitable equipment.
The package is preferably a semi-rigid container, such
as a clear plastic bag. The cut potatoes are placed in
the plastic bag and a vacuum is applied to evacuate the
package of oxygen. The evacuated vacuum bag is then
flushed with an inert gas mixture that preferably con-
tains CO2. The bag is then sealed to prevent leakage of
the gas outward and to prevent penetration of air into
the package.
Contrary to other prior art processes which utilize
modified atmosphere packaging (i.e. U.S. Patent No.
4,957,761 to Hale), the process of the invention re-
quires the use of carbon dioxide as an inert gas. This
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is because the solubility of carbon dioxide in surface
moisture produces a reduced pH due to the formation of
carbonic acid. The carbonic acid has a sterilizing
effect by reducing bacteria growth on the potato surfac-
es. As an example, the inert gas may contain 25% CO2 and
75% N2-
The product may then be packed in cases for distri-
bution. A solids content of the packed processed potato
pieces was determined to be about 27.3%. The product is
preferably on-site stored at about 30F (-1C) + 2 and
shipped at temperatures ranging from about 28F (-2C) to
32F (0C). Storage and distribution shelf life is 45
days minimum.
Control samples produced by the process of the
invention and held for 45 days showed minimal deteriora-
tion and achieved excellent color, odor, and flavor
characteristics.
Microbiological test results were as follows:
coliform < 10 colony forming units/gram
standard plate < 3000 colony forming units/gram
staphylococci < 50 colony forming units/gram
These values are lower than required governmental food
standards.
Odor in the head space of the packages was that of
good, clean oil and cooked potato. After 10 weeks,
there was no appearance or odor change.
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Refry time at the home or user is recommended at
1.5 to 3 minutes in 350-360F (176C-182C) oil in rela-
tively small quantities. This is about half the normal
fry time of frozen products.
It is apparent from the foregoing that a unique
potato preparation and packaging method has been provid-
ed. Potatoes processed in accordance with the invention
have the color and flavor of fresh cut potatoes and
contain no preservatives. While only one presently
preferred embodiment has been described in detail, as
will be apparent to those familiar with the art, certain
changes and modifications can be made without departing
from the scope of the invention as defined by the fol-
lowing claims.
