Note: Descriptions are shown in the official language in which they were submitted.
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Title: Process of Manufacturing Rapid Reconstitution Root Vegetable
Products
Field of the Invention
[0001] The invention relates to processes of producing quick frying
root
vegetable products. In particular, the invention relates to quick frying
potato
products that can be cooked to produce a product having potato flavour and
reduced colour variation.
Background of the Invention
[0002] Frozen, partially fried root vegetable products that only
require a
short period of further cooking before serving are widely available and used
in
both the food service markets and consumer markets. Such products are
generally referred to as par fried products. Par fried root vegetable products
are typically made from root vegetables such as potatoes, yams, carrots,
beets, yucca and sweet potato. The most common par fried root vegetable
products are made from potatoes (par fried potato products). Due to the large
market for par fried products, there is a constant demand for better products
and improved methods for producing such products.
[0003] One desired improvement is the reduction of reconstitution
(ie.
final cooking) time from the par fried product to the finished product to be
eaten by the consumer. The fastest method for reconstitution is by frying.
However, there is still a desire to reduce this finish frying time further to
improve process efficiencies while maintaining, or improving, final product
characteristics.
[0004] The purpose of the finish fry step is to cook the par fried
product,
for example, by browning the product and removing moisture from the par
fried product to an extent that the par fried product acquires the texture and
other properties of the cooked product. A par fried product having a higher
moisture content entering into the finish frying step, will require a longer
finish
frying time to remove moisture and produce a consumable product with
desired properties.
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[0005] A number of solutions have been proposed to reduce the
moisture content of the final par fried product and thus reduce the finish
frying
time.
[0006] In general, prior methods for reducing the moisture content
of
par fried potato products focused on the use of the frying process. Frying
provides an even and consistent method of heat transfer because the oil is in
full contact with the entire surface area of the immersed potato pieces.
Furthermore, the frying process permits a very fast rate of heat transfer to
the
potato pieces. Frying is considered desirable in a plant setting to ensure a
rapid production rate.
[0007] For example, one method for further reducing the moisture
content of par fried potato products is by extending the par frying time.
However, for potato products, excessive par frying causes loss of volatiles
leading to degradation of potato flavour. It also caramelizes the sugar on the
potato surface which causes colour change, and creates mottling and
variation, which are coloured spots or blotches of colour caused by the
scorching of the potato surface from the hot frying temperatures.
[0008] Another example of a method for further reducing the moisture
content of par fried potato products is a two-step par fry method which
reduces the moisture content of the potato product in two discrete frying
steps
such as in U.S. Patent No. 5,753,291 to Pederson et al. Typically, the two-
step par fry method allows greater moisture removal than is achievable in a
conventional single par fry step of the same overall frying time. However, the
two-step par fry method does not avoid all of the negative effects of extended
par frying. Further, a two-step par fry method is inefficient because it
reduces
the line rate in the factory (i.e. the rate of production of product),
requires
more equipment and the use of more oil for heating. The inefficiencies of the
process increase the effort and time required to produce the products. As
well, a third frying step subjects the product to additional heat necessary to
finish fry (cook) the product.
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[0009] A
further example of a method for reducing the moisture content
of par fried potato products is a two-step par fry process with an
intermediate
freezing step (fry-freeze-fry) as disclosed for example in U.S. Patent No.
4,590,080 to Pinegar and U.S. Patent No. 6,548,093 to Collinge et al. The
fry-freeze-fry process is another example of a process that attempts to reduce
the negative effects of extended par frying. The fry-freeze-fry process has
the
advantages of increased moisture removal of a two-step par fry process. It
also reduces the negative effects of the second par fry by freezing the
product
after the first par fry. When the frozen product enters the second par fry, a
substantial initial portion of the second par fry step is required to thaw and
reheat the frozen product back to frying temperature whereby the product is
actually maintained at frying temperature for a substantially shorter time
period. The reduced time that the product is subjected to frying temperatures
reduces the negative effects of frying. However, a fry-freeze-fry process has
similar inefficiency problems as the two-step process described above. The
fry-freeze-fry process also produces potato products that tend to lack flavour
and have more variability in texture and quality.
[0010]
Equilibration is another technique used for reducing the
negative effects of frying. The equilibration step is typically used after an
initial
drying step that involves applying heat to the product to dry it. This initial
drying step precedes par frying. The equilibration step is a resting step
where
the moisture from the center of the cooling product is allowed to rehydrate
the
surface of the product. The surface is typically drier from being closer to
the
heating source. The negative effects of extended par frying are reduced
when the product has been equilibrated in this manner prior to par frying.
Equilibration decreases the moisture difference between the surface and the
center of the product which reduces case hardening or effects of excessive
drying. The equilibration step typically involves resting the product on a
conveyor for 1-5 minutes at ambient temperature or circulating unheated air
over the product for 1-5 minutes. Equilibration would usually provide less
than 0.5% weight loss/minute, and this rate would decrease as the product
cooled. Equilibration has also been used between two frying steps (fry-
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equilibrate-fry process) to produce high solids French fries, typically in
excess
of 45% solids. Conventional French fries have solids of less than 36% so in a
process to produce high solids French fries, the second fry would typically
increase solids from less than 36% to 45% or higher.
[0011] There is a need for an improved method for producing par fried
products that have a more rapid reconstitution time and maintain or improve
upon the quality, texture and appearance of a conventional reconstituted
product.
Summary of the Invention
[0012] The invention relates to a method for producing rapid
reconstitution root vegetable products (ie. products capable of rapid
reconstitution) from par fried root vegetables. According to the methods, the
root vegetables are dried to a predetermined degree after they have been par
fried, so that the drying produces the rapid reconstitution root vegetable
products. This invention provides the first time that root vegetables have
been
dried after par frying with the conditions described herein. In a preferred
embodiment, the invention relates to methods of producing French fries and
other potato products. The drying step preferably comprises actively drying
the root vegetable products by applying conditions such as heat and humidity
to the root vegetable products after they have been par fried (typically
immediately after par frying). Other parameters such as pressure may also
be increased or decreased as desired. The invention also includes rapid
reconstitution root vegetable products, such as rapid reconstitution French
fries, prepared according to a method of the invention. Thus, the invention
also includes rapid reconstitution root vegetable products with unique
physical
properties as described in this application, such as a percentage weight loss
permitting cooking (finish frying) in 90 seconds or less, preferably 60
seconds
or less.
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[0013] The
invention also relates to a method for producing rapid
reconstitution root vegetable products from blanched root vegetables,
comprising
par frying the blanched root vegetables; and
next drying the root vegetables to produce the rapid reconstitution root
vegetable products.
[0014] In
one embodiment, the invention relates to a method for
producing rapid reconstitution root vegetable products from blanched root
vegetables, comprising
par frying the blanched root vegetables at a par frying temperature and
next applying heat and humidity for drying the root vegetables to produce the
rapid reconstitution root vegetable products.
[0015] The
method also optionally includes freezing and/or finish frying
the vegetable products. The vegetables are optionally dried at a moisture
removal rate comprising between 0.8-3% weight loss per minute. The
moisture removal rate optionally comprises between 0.8-2% weight loss per
minute or between 1-1.5% weight loss per minute. The vegetables are
optionally dried at a dehydrating temperature that is lower than the par
frying
temperature, for example, the dehydrating temperature is optionally between
50 C to 120 C, such as between 55 C to 70 C. The dehydrating temperature
is typically suitable to remove moisture and cause weight loss in the
vegetables without browning the vegetable surfaces or volatilizing or
degrading organic flavour components and causing loss of natural potato
flavor. The relative humidity or absolute humidity is typically suitable to
permit
moisture removal in a controlled manner from the vegetables without case
hardening of the vegetables. The humidity is optionally between about 40%
to 80% relative humidity, such as between about 60% to 75% relative
humidity. The drying step optionally reduces the weight of the vegetables to
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produce vegetable products that have a weight that is 5-25% less than the
weight of the vegetables at the start of the drying. The vegetable products
optionally have a weight that is 10-20% less than the weight of the vegetables
at the start of the drying. The vegetable products optionally have a total
weight loss after the post-fry drying between 30-75%, 40-75%, 50-75%, 60-
75%, 65-75%, 68-72%, or 70-75% (for example, at least: 40%, 50%, 60% or
70%). The vegetables are optionally selected from the group consisting of
potatoes (eg. French fries) yams, carrots and beets. The par frying step
optionally reduces the weight of the vegetables by 15-30% compared to the
weight of the vegetables at the start of the par frying step. The par frying
step
typically comprises frying the potatoes in oil for about 35-55 seconds at 180-
185 C. In certain embodiments, the drying comprises applying heat by
blowing heated air on the vegetables or the drying comprises applying heat by
blowing a heated convection air current on the vegetables. The drying step
optionally comprises applying heat by blowing a first air current and a second
air current on the vegetables, wherein the first air current and the second
air
current are blown in alternate directions. The drying step optionally further
comprises turning the vegetables while applying heat. In
certain
embodiments, turning the vegetables comprises moving the vegetables from
a first conveyor belt to a second conveyor belt. In methods of the invention,
the drying is typically free of frying of the cut potatoes. The methods
optionally further comprise finish frying the vegetable product in oil to
produce
a cooked vegetable product. The finish frying optionally comprises reducing
the moisture content of the vegetables to cause a weight loss of 10-40%
relative to the weight of the vegetables at the start of the finish frying
step.
The finish frying step optionally comprises frying the cut potatoes in oil for
about 60-75 seconds at 180-185 C. The
finish frying step is optionally
preceded by freezing the vegetables or the post-fry drying step is optionally
preceded by freezing the vegetables. In
certain embodiments, the
vegetables, such as French fries, are frozen prior to the post-fry drying step
and then refrozen after the post-fry drying step, prior to finish frying.
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[0016] Another embodiment of the invention relates to a method for
producing rapid reconstitution root vegetable products from root vegetables,
comprising
blanching the root vegetables;
optionally pre-fry drying the vegetables
par frying the blanched root vegetables at a par frying temperature; and
next applying heat and humidity for drying (post-fry drying) the root
vegetables to produce the rapid reconstitution root vegetable products.
Suitable conditions for the pre-fry drying step, the blanching step, the par
frying step and the post-fry drying step are described below. The method also
optionally includes freezing and/or finish frying the vegetables as described
herein.
[0017] Another embodiment of the invention relates to an apparatus
for
preparing rapid reconstitution root vegetable products from root vegetables
comprising:
a blancher for blanching the root vegetables;
a par fryer for frying the blanched root vegetables; and
a post-fry dryer.
[0018] In the apparatus, the post fry dryer optionally comprises a
means for applying heat and humidity to the vegetables and turning the
vegetables. The apparatus optionally further comprises a pre-fry dryer
[0019] Other features and advantages of the present invention will
become apparent from the following detailed description. It should be
understood, however, that the detailed description and the specific examples
while indicating preferred embodiments of the invention are given by way of
illustration only, since various changes and modifications within the spirit
and
scope of the invention will become apparent to those skilled in the art from
this detailed description.
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Brief Description of the Drawings
[0020] Embodiments of the invention will be described in relation to
the
drawings in which:
[0021] Figures la-d are block diagrams illustrating embodiments of the
process for preparing par fried root vegetable products in accordance with the
present invention; a) shows a block diagram of an embodiment of the
invention showing consecutive process steps such as blanching, pre-fry
drying, par frying, post-fry drying, freezing and finish-frying; b) shows a
process of the present invention without the pre-fry drying step; c) shows a
block diagram of one embodiment of the process of the present invention
without the freezing step; d) shows a block diagram of the process of this
embodiment of the present invention where the par frying step and freezing
step are carried out prior to the post-fry drying step.
[0022] Figures 2a and 2b are photos showing cooked French fries
prepared in accordance with embodiments of the present invention (left) and
French fries prepared in accordance with the prior art two-step par fry
process
(right);
[0023] Figure 3 is a photo showing an embodiment of the post-fry
dryer
drying French fries.
Detailed Description of the Invention
[0024] The invention relates to methods for preparation of rapid
reconstitution root vegetable products. The invention is useful for food
service
restaurant and retail fried root vegetable products.
[0025] The invention also includes an apparatus for preparation of
rapid
reconstitution root vegetable products. Components useful to practice the
invention include: a blancher, a parfryer and a post-fry dryer. In one
embodiment, the apparatus consists of a washer, peeler and cutter for the
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potatoes as well as a blancher (e.g. screw blancher, belt blancher or steam
blancher), a pre-fry dryer (e.g. multi-stage or single-stage dryer or
impingement dryer), a parfryer (e.g. oil immersion fryer or deluge fryer), a
post-fry dryer (e.g. multi-stage or single-stage dryer or impingement dryer)
and a freezer. The parfryer is optionally a conventional parfryer. The dryer
is
optionally an impingement dryer or conventional dryer. The freezer is
optionally an individual quick-freeze freezer (e.g. continuous belt freezer
and
freezing tunnel).
[0026] The present invention can be applied generally to all root
vegetables suitable for frying. Root vegetable products include products
made from root vegetables such as potatoes, yam, carrots and beets. The
most common par fried root vegetable products are made from potatoes and
the following description primarily refers to potato products. It will be
readily
apparent that parameters may be adapted depending on the type of potato
variety used, since different varieties have different contents of sugars and
other solids. It will also be readily apparent that one can adapt the potato
methods and apparatus to other root vegetables.
[0027] In an embodiment of this invention, raw potatoes are typically
subjected to preliminary steps that may include one or more of washing,
peeling, trimming and inspecting for defects. After the preliminary steps, the
raw potatoes are formed into potato products (e.g. cut potatoes) such as
French fries produced from potatoes according to well-known methods. An
example of a suitable sized cut would have a cross-section dimension from
about 3/16 to 1.5 inch square and rectangular in each of width and height and
having various combinations of lengths. The methods described herein are
also applicable to other more special cuts, for instance, helical cuts, spiral
cuts, crinkle cuts, concertina cuts, waffle cuts, lattice cuts, cube cuts,
wedges,
dollar chips, slices, triangle fries, crescent cuts and many other shapes. The
methods described herein are also applicable to formed products from
potatoes, such as tots, croquettes, square and round patties and hash browns
typically made from pieces of potato and other ingredients mixed and formed
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to make specialty (byproduct) potato products. Processed components, such
as starches are optionally used to make a dough that can be extruded into
various shapes. Thus the term "potato products" refers to any of these and
other cut shapes or products formed from potatoes to which the method is
usefully applied. The term "potato products" is further defined below by
reference to the stage of processing of the potato products, such as
"blanched potato products" used to refer to potato products after they have
been blanched, but before they are par fried. Root vegetable products are
prepared in a similar manner.
[0028] Embodiments of the present invention will be further described
by examples using potato products. Figure 1a shows a block diagram of an
embodiment of the invention. After the potatoes are peeled, cut and washed,
the potato products are typically subjected to a blanching step 10 to produce
a
blanched potato product. Blanching partially cooks the potato products,
assists in controlling reducing sugars and stops enzyme actions which can
cause loss of flavour, colour and texture. The blanching step 10 typically
consists of scalding the potato products in hot water, steam or frying oil for
a
short time. In one example of blanching, the potato products (19/64" square)
are immersed in water at 65-85 C for about 5-20 minutes. This blanching
step 10 optionally causes a weight loss of about 2% in the potato products
compared to the weight at the start of the step due to the loss of some of the
potato solids to the water by leaching process. Blanched root vegetable
products are prepared in a similar manner.
[0029] The blanched, potato products are then optionally subjected
to a
pre-fry drying step 12 to reduce moisture content. Drying is optionally done
in
an oven with heat and humidity control. The pre-fry drying step 12 changes
the texture of the product by making a continuous dried layer called a 'skin'
(also referred to as developing external texture) on the product prior to
frying.
The pre-fry drying step 12 removes some of the moisture captured from the
blanching step 10 before a par frying step 14 to reduce oil absorption and
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degradation of the frying medium. This reduces the amount of time, oil and
size of equipment needed for the par frying step 14.
[0030] The pre-fry drying step 12 may be omitted, for example, if
making a product that does not require drying (e.g. low-solids French fries or
fresh-cut/homestyle French fries). The process of the present invention
without the pre-fry drying step 12 is illustrated in the block diagram of
Figure
lb.
[0031] The potato products are preferably blanched in blanching step
just prior to the pre-fry drying step 12 so that the blanched potato products
10 are still hot when the pre-fry drying step 12 begins, and moisture
removal is
facilitated. This pre-fry drying step 12 is controlled so that approximately
10-
12% of the weight (relative to the weight at the start of this step) of the
potato
products is removed as moisture. Moisture removal can vary by product from
5-20% by weight depending upon the desired quality attributes for a given
product. Pre-fry drying step 12 conditions typically provide a moisture
removal rate of between 0.5-1.2% weight loss per minute, for example, about
1% weight loss per minute. Drying conditions produce enough moisture
removal to dry the product without causing blistering or case hardening. For
example, if this pre-fry drying step 12 reduces the moisture content by about
10% by weight then the solids percentage by weight may increase to 10%.
The potatoes are dried at 35-100 C, typically 55 C at a relative humidity of
about 40-80%, typically 75% for about 5-20 minutes, typically 15 minutes.
The variables for the drying conditions are dependent on the type of dryer
used for this pre-fry drying step 12. A dryer that holds a product for 5-8
minutes requires drying conditions that are different than a dryer that holds
a
product for 20 minutes in order to obtain an identical resulting weight loss
in
both dryers. A smaller dryer unit requires more heat and lower humidity levels
compared to a larger dryer in order to obtain adequate moisture removal
within a given time.
[0032] After the pre-fry drying step 12, the pre-fry dried potato products
are then contacted with oil in a par frying step 14 to produce a par fried
potato
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product. Par frying step 14 or "partial fry" is the cooking stage where the
potato products are partially cooked in oil. Par frying step 14 includes any
cooking method that partially cooks the potato products in oil, including
immersion of potato products in oil, and spraying and coating potato products
with oil and heating at high temperatures.
[0033] In an embodiment of the par frying step 14, the processing
parameters are controlled to produce a par fried potato product having a
further weight loss of between 15-30% (relative to the weight at the start of
this step) and preferably a weight loss of 20-25%. Par frying typically causes
very rapid weight loss, for example, at a rate of about 25% weight
loss/minute.
Total moisture weight loss at this point is a combination of the pre-fry dry
step
12 weight loss and the par fry step 14 weight loss. Total weight loss after
par
frying step 14 is optionally 20-50% by weight (irrespective of whether a pre-
fry
dry step 12 is used). The potato products are typically par fried by immersion
in oil to achieve this weight. In preparing a product for a food service
restaurant (i.e. for a quick serve restaurant product) a suitable par frying
temperature is optionally between 170-200 C, more preferably 175-195 C,
and typically 185 C. Time can vary from 30-90 seconds, more preferably 30-
60 seconds, typically 50 seconds. To obtain the same endpoint without a pre-
fry drying step 12, weight losses in the par frying step 14 have to be
increased
to obtain the desired total weight of the par fried product. Other suitable
par
frying conditions will be readily apparent to those skilled in the art. Other
par
fried root vegetables are prepared in a similar manner.
[0034] After the par frying step 14, the potato products are then
further
dried in a post-fry drying step 16 to reduce moisture content in a post-fry
dryer
(e.g. oven) with heat and humidity control. This step produces a rapid
reconstitution potato product capable of being cooked (finish fried) in 90
seconds or less, preferably 60 seconds or less. In the post-fry drying step
16,
more drying force is required to remove moisture from the product because
the product is becoming more dried and has an oil coating from the par frying
step and optionally a skin from the pre-fry drying step that creates a barrier
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that reduces (impedes) moisture removal. The potato products are preferably
subjected to par frying step 14 just prior to this post-fry drying step 16, so
that
the potato products are still hot when the post-fry drying step 16 begins, and
moisture removal is facilitated. Par fried potatoes are typically moved to the
post-fry drying step 16 within seconds (for example, less than 15, 30 or 60
seconds) or minutes after the par frying step 14.
[0035] Drying equipment used for the post-fry drying step 16
typically
provides even heat and humidity control to the product surface, for example,
by circulating air in sections of alternating direction or by transferring
product
regularly to another belt to turn the product over thereby exposing areas that
have not been in contact with the heated air. In this manner a very even
moisture loss will be obtained over the drying retention time. Moisture is
preferably removed at a rate which does not exceed the products' ability to
pass moisture from its surface (one should wick moisture without desiccating
the potato surface and causing cells to collapse). Use of this rate prevents
what is called case hardening, which is a drying process that damages the cut
product surface by fast drying that forms a barrier on the outside of the
potato
causing reduced permeability to moisture and impeding further moisture
evaporation. Case hardening produces a blistered French fry surface and a
tough, chewy external surface that does not have good eating characteristics.
[0036] This post-fry drying step 16 achieves the desired moisture
content removal without the negative effects of extended frying. The lower
moisture content in the post-fry dried potato products (i.e. the rapid
reconstitution potato products) after the post-fry dry step 16 has the
advantage of reducing the final finish frying time because less moisture is
required to be removed to reach the final moisture content of a cooked
product. The post-fry drying step 16 does not slow down the line rate. The
post-fry dryer is typically added to the line and does not cause pre-fry
drying
or par frying times to be extended to a point whereby line rate reductions are
needed to manufacture the product.
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[0037] In this post-fry drying step 16, the processing parameters are
controlled to produce a rapid reconstitution potato product optionally having
a
further weight loss of 5-25%, and more preferably a weight loss of 10-20%
such as about 15% (relative to the weight at the start of the post-fry drying
step). Total weight loss after the post-fry drying is optionally 30-75%, 40-
75%,
50-75%, 60-75%, 65-75%, 68-72%, or 70-75% (for example, at least: 40%,
50%, 60% or 70%). Higher weight loss % provides more rapid reconstitution.
A conventional potato product would have a total weight loss between 20-
30%. In one embodiment, the potatoes are dried for 5-30 minutes, typically
20 minutes, preferably 15-25 minutes at a temperature between 50-120 C,
typically 55-70 C and at a relative humidity of about 40-80%, typically 60%-
75%. The time and temperature varies considerably based upon the product
dimensions as they dictate the rate at which moisture may pass while
avoiding case hardening effects. An advantage of using the invention to
produce potato products having weight loss in this range is that the invention
uses less par frying and preserves potato flavour. The methods of the
invention also reduce colour mottling and variation and produce a desirable
texture. The post-fry drying step also results in a product with reduced
acrylamide because it is fried for a shorter reconstitution time. Thus, the
invention also relates to methods of reducing acrylamide in a fried root
vegetable product, particularly a fried potato product by carrying out the
steps
of the invention as described in this application.
[0038] As compared to the pre-fry drying step 12, the conditions
above
for the post-fry drying step 16 show an increase in retention time,
temperature
and lower humidity conditions to achieve the endpoint weight losses required
for this process step and produce the rapid reconstitution product. For
example, the moisture removal rate is optionally between 0.8-3% weight loss
per minute, 0.8-2% weight loss per minute and more typically between 1-1.5%
weight loss per minute for the post-fry drying step 16. This moisture removal
rate is chosen to avoid creating variability in quality and texture in the
final
product due to uneven drying conditions or uneven rates of moisture removal.
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As a comparison, the moisture removal rate during frying is approximately
25% weight loss per minute which is significantly faster than the moisture
removal rate of the post-fry drying step 16. However, the slower post-fry
drying rate of moisture removal avoids the negative effects caused by frying.
[0039] After the post-
fry drying step 16, the potato products are
optionally cooled and frozen in a conventional manner in a freezing step 18,
for example, by cooling them to a temperature of about ¨5 to ¨20 C such as
on a continuous belt freezer and freezing tunnel. The frozen product may
then be packaged, stored and shipped. The freezing step 18 may be
eliminated for products that have long shelf life or for products that are
intended to be finish cooked shortly after the post-fry drying step. Freezing
may be avoided and replaced with cooling for what is termed "chilled French
fries" or "fresh fries."
[0040] When the potato
products are ready for consumption they are
finish cooked, for example by frying, baking, or other forms of suitable
heating, to cook the potato products to a condition suitable for consumption
by
the end user. The par fried potatoes are optionally finish cooked either from
the frozen state after the freezing step 18 or directly from the post-fry
drying
step 16. Figure 1c shows a block diagram of one embodiment of the process
of the present invention where the freezing step 18 is removed. Frozen
product can also be thawed before reconstitution frying to assist the frying
step by further reducing cooking times.
[0041] The time and
temperature for finish cooking the par fried
products of the present invention will vary depending upon the type of the
root
vegetable, the quantity of the root vegetable, the shape and size of the root
vegetable, the initial temperature, and the method of cooking.
[0042] In one
embodiment, the par fried potato products are finish fried
in a finish frying step 20. In the finish frying step 20, the potato products
are
optionally fried in oil at 165-190 C, typically 170-180 C for 45-90 seconds,
such as 75 seconds. Alternatively, the par fried potato products may be finish
cooked in a conventional home baking oven. In a conventional home baking
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oven the cut potato products may be baked at 120-260 C, more typically 170-
180 C for 3-10 minutes, typically 5 minutes to produce a product in much
shorter cooking times with final attributes usually seen in products cooked
under similar methods with more than 2-4 times more cooking time.
[0043] A reduced finish frying time of, for example, 45-90 seconds for
potato products provides advantages over prior methods of making French
fries. The shorter finish frying time and consequently shorter period of
exposure of the potato products to high temperatures produces better potato
flavours due to less loss of volatiles and nutrients, assuming that these
attributes were not previously removed from the product when removing
moisture, for example by extra par frying or retention time. This adds flavour
to the final cut potato product, more consistent brighter golden colours due
to
less caramelization of the sugars, reduced colour mottling and variation due
to
shorter exposure to hot frying temperatures and thus less opportunity for
scorching of the potato surface. The French fries made in accordance with
the process of the present invention have less mottling and variation
compared with French fries made from a conventional process (Fig. 2a and
2b). The final product produced according to this invention also has better
taste qualities such as a thin crisp shell with a tender texture, a mealy
inner
core and stronger potato flavours. Another benefit of the invention is that
one
can now produce French fries from higher sugar content potatoes. Typically,
low sugar potatoes are preferred for frying to reduce color variations and
mottling that occur when sugars brown during frying. Thus, the process of the
invention, by reducing frying time, allows use of a wider range of potato and
vegetable starting materials which provides for greater flexibility.
[0044] The post-fry drying step 16 of this present invention, in
addition
to providing a product having superior internal and external texture
characteristics as compared to present processes, also enables the
production of French fries with considerably less energy consumption and
less use of oil than is required with potato products produced without the
final
drying step. The shorter finish frying step reduces oil waste in the
restaurant,
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requires less energy and increases the frying capacity of fryers in the
restaurant to produce cut potato products. The reduced frying times provide
speed and convenience to the end user.
[0045] In one embodiment, conventional French fry cutting and
blanching is performed on a 0.290 inch (1/4 inch) shoestring cut. A dryer is
set
up at 50 C at 70% relative humidity for about 14 minutes to produce a weight
loss in the range of about 10-12%. The product is par fried for 45 seconds at
180 C to provide a weight loss of about 19-22%. The product is put in a dryer
(post-fry dryer) for 20 minutes at 100 C and 60% relative humidity to produce
a weight loss of about 17-21%. The product is then frozen. The frozen
product is reconstituted in 60-90 seconds at from 168-182 C (335-360 F).
Reconstitution for 75 seconds at 174 C (345 F) with a final weight loss of
about 35% gives final product attributes of improved potato flavour,
significant
reductions in colour variations and mottling and desirable internal and
external
texture attributes. The process can be readily adapted by modifying time,
temperature and humidity parameters for different sizes and customer
requirements for color and texture. The product exceeds the quality of the
conventional product cooked for 2-3.5 minute retention times.
[0046] The invention is useful for preparing product for retail
store sale
or for restaurant sale. In an embodiment of the process of the invention, the
post-fry dry step 16 and finish fry step 20 can be carried out at a restaurant
or
other reheating site. Figure 1d shows a block diagram of the process of this
embodiment of the present invention where the par frying step 14 and
freezing step 18 are carried out prior to the post-fry drying step 16. In this
embodiment, conventional frozen par fried products can be post-fry dried at a
restaurant, or other reheating site. In this embodiment of the post-fry drying
step 16, the par fried product is placed in a drying oven to heat and remove
moisture from the product in a controlled manner, with heat, circulated air
and
humidity control, to obtain the desired weight loss to allow for a reduced
frying
reconstitution time. The post-fry drying of the product after par fry and
freezing produces a similar effect to that obtained where the process of the
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invention is carried out in a plant setting where the freezing step 18 is
carried
out after the post-fry dry step 16. One example of a post-fry dryer with heat
and humidity control that can be used in a restaurant site is shown in Figure
3.
[0047] The present invention also provides a new method of preparing
and serving French fries that will improve product quality and reduce waste.
Currently, in a restaurant setting, multiple portions of root vegetables such
as
French fries are cooked at the same time. It has typically been necessary to
cook an oversupply of French fries because customers often will not want to
wait for 2-3 minutes for a single portion of French fries to be cooked. A fast-
food restaurant also does not wish to have long line ups of customers waiting
for food to be cooked. As a result, the oversupply of cooked French fries are
held in their frying basket or transferred to a holding container where they
remain until they are served to a customer. If the French fries are not all
served promptly, they get cold which is unacceptable for customers.
Reheating cold French fries after finish frying is also undesirable so
typically a
heating lamp or other heating device is used to keep the cooked French fries
warm until they are served to a customer. However, the quality of the French
fries is reduced if they are kept under a heat source for a prolonged period
of
time. Thus, if the oversupply of French fries is not sold quickly, restaurants
are faced with the problem of either serving customers a lower quality product
or discarding the older product. The present invention overcomes this
problem by providing a rapid reconstitution root vegetable product, such as
rapid reconstitution French fries, produced according to methods of the
invention. For example, since rapid reconstitution French fries cook so
quickly, it is possible to prepare smaller portions of French fries because
subsequent portions can be prepared quickly as needed, without causing
bottlenecks of customers waiting for French fries. As well, rapid
reconstitution
French fries can even be cooked in an individual size portion since each
customer would only have to wait a short time, such as one minute, for the
French fries to cook instead of the current 2-3 minutes using conventional
French fries. Thus, the invention relates to a method of preparing a cooked
portion of root vegetable product, such as French fries, comprising:
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providing a single portion (or a plurality of single portions) of rapid
reconstitution root vegetable product (i.e. prepared according to a
method described in this application), for example, a portion size
intended to be a single serving such as a small, medium, large or extra
large serving. This serving is optionally a 10g, 25g, 40g, 50g, 75g,
100g, 200g or 250g serving or a portion amount falling in a range
between two of the aforementioned masses. The portion is optionally
provided in a single package or readily dispensed from a larger
package;
finish frying the single portion of the rapid reconstitution root vegetable
product, for example, for less than 90 seconds or less than 60
seconds; and
packaging the finish fried rapid reconstitution root vegetable product
after finish frying for service to a customer (e.g. placing the finish fried
product in a container such as a box, bag, bowl or plate made of a
material such as styrofoam, glass, plastic, paper or cardboard). In one
embodiment, the single portions are pre-packaged and the product
may be removed from the package or cooked in the package (i.e.
package is permeable to oil). Packaging for service to a customer
optionally means placing the product in a container (e.g. bag or box) for
take-out or placing the product on a tray.
[0048] In
one embodiment of the method, a customer provides a
request for a single portion (or a plurality of single portions) of fried root
vegetable to a food service host (e.g. waiter or waitress) and a food service
cook then performs the aforementioned method steps comprising providing a
single portion of rapid reconstitution root vegetable product, finish frying
the
single portion of the rapid reconstitution root vegetable product, and
packaging the finish fried rapid reconstitution root vegetable product after
finish frying. The request is optionally made at a food service counter or
drive
through section and the product is delivered by a food service host to the
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customer at the counter, a table or drive through section. One or more
persons may provide the functions of food service host or cook.
[0049] Embodiments of the present invention are described below with
reference to the examples. The examples are illustrative and are not intended
to limit the scope of the invention.
Example 1
[0060] Frozen commercial 1/4 inch square par fried potato products
(cut potato pieces in the form of French fries) were used in this example.
This
example shows that processes of the invention may be applied to frozen
French fries produced by conventional methods. Of course, it will also be
readily apparent that a freezing step may be omitted entirely or carried out
only after a post-fry drying step. As an illustration, a typical process for
producing frozen French fries could include peeling, washing, trimming and
cutting axially to form cut potato pieces of 1/4 inch square cross-section.
The
cut potato pieces are then blanched in hot water or steam and partially dried
in a pre-fry dry step with hot air such that the potato pieces are reduced in
weight, for example, by about 10% and have a corresponding moisture
content reduction of about 10%. The partially dried cut potato pieces are then
par fried in oil for using par frying conditions such as about 35-55 seconds
at
180-185 C. The par fried cut potato pieces are then cooled and frozen in a
blast freezer, for example, at ¨25 C and packaged. The par fried cut potato
pieces typically have a moisture content of about 64% and a fat content of
about 6% and total solids of about 36%.
[0051] For example 1, about 680.0g of the frozen par fried cut potato
pieces were placed on a tray and further processed by drying in the final
drying step in a preheated convection oven, with a pan of water for
maintaining humidity level, for 15 minutes at 250 F (121 C). The resulting
dried cut potato pieces weighed 599.5g which amounted to a weight loss of
11.8%. The dried cut potato pieces were then finish fried for 1.5 minutes at
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335 F (168 C). The resulting fried cut potato pieces weighed 457.0g which
amounted to a further weight loss of 23.8%. The total weight loss for the
final
drying step and the finish frying step was 32.8%.
Example 2
[0052] About 680.5g of the same frozen par fried cut potato pieces
used in Example 1 were further processed by drying in the final drying step in
a preheated convection oven, with a pan of water for maintaining humidity
level, for 15 minutes at 250 F (121 C). The resulting dried cut potato pieces
weighed 590.5g which amounted to a weight loss of 13.2%. The dried cut
potato pieces were then finish fried for 1.0 minute at 345 F (174 C). The
resulting fried cut potato pieces weighed 478.0g which amounted to a further
weight loss of 19.1%. The total weight loss for the final drying step and the
finish frying step was 29.8% (this weight loss is additional to the weight
loss
that occurred with factory prior to frying of the frozen commercial French
fries).
Example 3
[0053] About 680.5g of the same frozen par fried cut potato pieces
used in Example 1 were further processed by drying in the final drying step in
a preheated convection oven, with a pan of water for maintaining humidity
level, for 20 minutes at 250 F (121 C). The resulting dried cut potato pieces
weighed 558.5g which amounted to a weight loss of 17.9%. The dried cut
potato pieces were then finish fried for 75 seconds at 345 F (174 C). The
resulting fried cut potato pieces weighed 459.0g which amounted to a further
weight loss of 17.8%. The total weight loss for the final drying step and the
finish frying step was 32.5%.
Example 4
[0054] About 680.5g of the same frozen par fried cut potato pieces
used in Example 1 was further processed by drying in the final drying step in
a
preheated convection oven, with a pan of water for maintaining humidity level,
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for 15 minutes at 250 F (121 C). The resulting dried cut potato pieces
weighed 560.5g which amounted to a weight loss of 17.6%. The dried cut
potato pieces were then finish fried for 75 seconds at 345 F (174 C). The
resulting fried cut potato pieces weighed 455.8g which amounted to a further
weight loss of 18.7%. The total weight loss for the final drying step and the
finish frying step was 33.0%.
Example 5
[0055] About 680.5g of the same frozen par fried cut potato pieces
used in Example 1 were further processed by drying in the final drying step in
a Henny Penny Smart Cooking System (SCS Model) Model SCE 061 with
relative humidity set at 75%, fan speed set at the 4th setting, for 20 minutes
at
250 F (121 C). This cooking system has air temperature, time and humidity
controls and therefore allows greater control over the moisture removal rate.
The product was loaded in its frying basket into the cooking system (see e.g.
Fig. 3). The resulting dried cut potato pieces weighed 585.5g for a total
weight loss of 14.0%. The dried cut potatos were then finish fried for 65
seconds at 335 F (168 C). The resulting fried cut potato pieces weighed
477.5g which amounted to a total weight loss of 29.8% from the weight of the
potato products prior to the drying step.
Example 6
[0056] About 680.0g of the same frozen par fried cut potato pieces
used in Example 1 were further processed by drying in the final drying step in
a Henny Penny Smart Cooking System (SCS Model) Model SCE 061 with
relative humidity set at 75%, fan speed set at the 4th setting, for 25 minutes
at
250 F (121 C). The resulting dried cut potato pieces weighed 544.5g which
amounted to a weight loss of 19.9%. The dried cut potato pieces were then
finish fried for 65 seconds at 335 F (168 C). The resulting fried cut potato
pieces weighed 459.5g which amounted to a total weight loss of 32.4% from
the weight of the potato products prior to the drying step.
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Example 7
[0057] About 681.5g of the same frozen par fried cut potato pieces
used in Example 1 were further processed by drying in the final drying step in
a Henny Penny Smart Cooking System (SCS Model) Model SCE 061 with
relative humidity set at 75%, fan speed set at the 4th setting, for 20 minutes
at
250 F (121 C). The resulting dried cut potato pieces weighed 575.0g which
amounted to a weight loss of 15.6%. The dried cut potato pieces were then
finish fried for 75 seconds at 335 F (168 C). The resulting fried cut potato
pieces weighed 465.5g which amounted to a total weight loss of 31.7% from
the weight of the potato products prior to the drying step.
Example 8
[0058] About 679.5g of the same frozen par fried cut potato pieces
used in Example 1 were further processed by drying in the final drying step in
a Henny Penny Smart Cooking System (SCS Model) Model SCE 061 with
relative humidity set at 75%, fan speed set at the 4th setting, for 25 minutes
at
250 F (121 C). The resulting dried cut potato pieces weighed 559.0g which
amounted to a weight loss of 17.7%. The dried cut potato pieces were then
finish fried for 75 seconds at 335 F (168 C). The resulting fried cut potato
pieces weighed 448.0g which amounted to a total weight loss of 34.1% from
the weight of the potato products prior to the drying step.
[0059] Figures 2a and 2b shows a comparison of the French fries
between French fries made in accordance with the processes of the invention
as illustrated in the Examples 1-8 which are shown on the left side of the
photo and the French fries made from a conventional two-step par fry process
which are shown on the right side of the photo. The French fries made in
accordance with the process of the present invention appear lighter and with
less mottling and variation compared with French fries made from a
conventional process. The final product produced according to this invention
also has better tasting qualities such as a thin crisp shell with a tender
texture,
a mealy inner core and stronger potato flavours.
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Example 9
[0060] In this example, 1423 g of 9/32 strips were
blanched for 15
minutes at 75 C and placed in a dip of 0.8%SAPP/0.5%dextrose at 65 C for
60 sec, followed by a dry time of 10 minutes at 45 C (weight loss: 7 %).
Following a rest of 4 minutes at room temperature, strips were par fried for
70
seconds at 185 C.(par fry weight loss: 24%). Strips were subjected to the
post-fry drying step before freezing to -20 C (8 minutes chill/12 minutes
freeze). About 977.8g of par fried material was dried between 30 and 27
minutes using a dual- zone industrial dryer in static mode set between 110
and 125 C, preferably 115 C, 15% humidity, with two pauses of one minute to
flip the strips. As noted previously, dryer conditions, such as temperature
and
relative humidity are readily adjusted by one of skill in the art according to
the
dryer used, so the relative humidity is lower in this example than in Example
8. The resulting dried cut potato pieces weighed 634g which amounted to a
weight loss of 35.2% and drying rate of 12.5 g moisture/min (during a
continuous process, parfried material would be routed through a high
temperature, ideally impingement type dryer independent of the standard
process dryer). The dried potato pieces were then chilled and frozen, as
described in example 1. The resulting frozen potato pieces weighed 605g.
The frozen dried cut potato pieces were then finish fried for 65 seconds at
168 C. The resulting fried cut potato pieces weighed 546g which amounted to
a further weight loss of 9.8% and a finish solids of ¨ 58%. Total % weight
loss
from par fry, post-fry drying and finish fry was 69%.
[0061] As a variant to this process, 9/32 par-fried frozen
strips were
subjected to the secondary dehydration step at similar conditions as
described above and then refrozen before it is finished fried for 65seconds at
168 C. Tubers were preheated before cutting by placing in water between
54 C and 56 C for 38 min. Blanching was at about 80-85 C for 8-9 min. Pre-
fry drying occurred between 47-54 C for about 14 min. Par Frying was done
at 180-190 C for 60 sec. Product was frozen in 8 min 45 sec to a discharge
temperature of -22 C. Product was then post-fry dried between 30 and 27
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minutes using a dual- zone industrial dryer in static mode set between 110
and 125 C, preferably 115 C, 15% humidity. Weight loss was about 31% at a
drying rate of 11 g moisture/min. The dried potato pieces were then refrozen
to -23 C. The frozen dried cut potato pieces were then finish fried for 65
seconds at 168 C. Total % weight loss from par fry, post-fry drying and finish
fry was 65 %.
[0062] The present invention has been described in terms of
particular
embodiments found or proposed by the present inventors to comprise
preferred modes for the practice of the invention. It will be appreciated by
those of skill in the art that, in light of the present disclosure, numerous
modifications and changes can be made in the particular embodiments
exemplified without departing from the intended scope of the invention. All
such modifications are intended to be included within the scope of the
appended claims.
