Process for preparing improved oven-finished french fries

The present invention provides a process for quickly oven finishing (baking) oil-enrobed prebake fries in as litle as 0.75 minute at a temperature of from about 325.degree. F. (162.degree. C.) to about 800.degree. F. (426.degree. C.) to provide oven-finished French fries that have virtually the same taste and characteristics as deep fat fried finished French fries. The oven-finished shoestring French fries of this invention are characterized as having: a bulk moisture of from about 32% to about 46%; a total fat content of from about 12% to about 25%; and a French Fry Texture Value of at least about 200. Preferably the fries have a surface water activity (Aw) of less than about 0.55 and an internal moisture content of from about 55% to about 80%.

TECHNICAL FIELD 
The present invention relates to a process for oven-finishing French fries. 
BACKGROUND OF THE INVENTION 
French fries are prepared by deep fat frying fresh or "par-fried" potato 
strips. A major drawback associated with deep fat frying is handling the 
hot frying oil. Baking the par-fries in an oven avoids this hot frying oil 
problem. However, there are some major problems associated with state of 
the art oven-finished French fries. One of the major problems is that a 
high quality French fry that tastes deep fried is difficult to 
consistently duplicate in an oven. In other words, a reliable process for 
making high quality deep fat fried-like oven finished French fries is 
heretofore unknown. Current oven-finished French fries are generally too 
limp and soggy or too dry and tough. High quality deep fat fried French 
fries have a moist interior surrounded by a crisp yet tender outer surface 
or crust. 
It has now been surprisingly discovered that high quality French fries can 
be prepared quickly and reliably by a specific process comprising baking 
oil enrobed prebake fries in an oven. 
It is an object of the present invention to provide a process for making 
high quality deep fat fried-like French fries in an oven. It is another 
object of the present invention to provide a fast food process for quickly 
finishing frozen par-fries in an oven. It is yet another object of the 
present invention to provide improved tasting high quality deep fat 
fried-like oven-finished French fries. Other objects of the present 
invention will become apparent in view of the following description. 
SUMMARY OF THE INVENTION 
The present invention provides a process for quickly oven finishing 
(baking) oil-enrobed prebake fries to provide oven-finished French fries 
that have virtually the same taste and characteristics as deep fat fried 
French fries. The oven-finished shoestring French fries of this invention 
are characterized as having: a bulk moisture of from about 32% to about 
46%; a total fat content of ftom about 12% to about 25% and a Texture 
Value of at least about 200. Preferably the fries have a surface water 
activity (Aw) of less than about 0.55, and an internal moisture content of 
from about 55% to about 80%. 
DETAILED DESCRIPTION OF THE INVENTION 
Unless otherwise stated, all percentages, ratios and proportions expressed 
herein are by weight. As used herein, the terms "par-fry" or "par-fried" 
or "par-fries" all refer to potato strips that have been subjected to at 
least one frying process; e.g., deep-fat frying. The parfry has a lower 
moisture than a raw potato strip and contains some fat or oil from the 
frying process. 
The term "prebake fries" refers to parfries that have been coated (enrobed) 
with oil on the surface and are ready for oven-finishing in accordance 
with the present invention. 
The term "oven-finished" refers to a product that has been subjected to a 
baking process and is in the ready-to-eat form. 
The terms "fat" or "oil" both refer to any edible fatty substances in a 
general sense; e.g., 100% natural or 100% synthesized fats and oils, etc., 
unless otherwise specified. Preferred oils consist essentially of 
triglycerides, such as, for example soybean oil, corn oil, cottonseed oil, 
sunflower oil, palm oil, coconut oil, fish oil, and edible animal oil such 
as tallow. These oils can be partially or completely hydrogenated or 
modified by interesterification. The terms "fat" or "oil" also refer 100% 
non-toxic fatty materials having properties similar to triglycerides. The 
terms "fat" or "oil" in general include fat-substitutes, which materials 
may be partially or fully nondigestible. 
The terms "fat" and "oil" are used interchangeably unless otherwise 
specified. 
The term "fat substitute" refers to those edible fatty materials that are 
partially or totally nondigestible, e.g., polyol fatty acid polyesters, 
such as olestra. 
The term "conditioned oil" refers to oil which has been previously used for 
frying for such a time that it has developed fried flavor. 
The terms "enrobed" or "coated" refers to a product having a substantially 
uniform coating of oil or fat on the surface. The oil coating can be 
discontinuous (i.e. globules or droplets) or continuous. Preferably at 
least 75% of the surface is coated. 
The present invention relates to a process for finish cooking oil-enrobed 
prebake fries by baking the oil-enrobed prebake fries in an oven for from 
about 0.75 minute to about 15 minutes at a temperature of from about 
325.degree. F. (162.degree. C.) to about 800.degree. F. (426.degree. C.). 
The oven-finished French fries of this invention taste as if they are deep 
fat fried French fries. They are superior in quality compared to the state 
of the art oven-finished French fries. The oven-finished French fries made 
by the process of this invention (shoestring-cut) have a bulk moisture of 
from about 32% to about 46%; a total fat content of from about 12% to 
about 25%; and a Texture Value of at least about 200. Preferably the fries 
have a surface water activity (Aw) of less than about 0.55 and an internal 
moisture content of from about 55% to about 80%. 
Some important attributes in French fried potatoes are bulk moisture, total 
fat, surface water activity (Aw), crust crispness and interior texture. 
The external surfaces of good textured French fries are moderately crisp 
and not excessively oily. The interior portions are tender, mealy and free 
from sogginess. A French Fry Texture Value, as defined herein, has been 
developed to characterize these fries, a Texture Value of greater than 
about 200 represents a crisp fry with a moist interior. 
Selected oil-enrobed prebake fries with certain bulk moistures and oil 
levels, when oven finished via the process described herein, provide 
superior French fries over the state of the art oven-finished French 
fries. 
Prebake Fries 
The prebake fries of this invention provide greater flexibility in meal 
preparation, simplification in storage, inventory control and are more 
uniform in quality versus preparing French fries directly from raw 
potatoes. 
Raw potatoes or par-fried potato strips are starting materials for the 
prebake fries. Raw potatoes (e.g., Russet Burbanks) are washed, peeled, 
trimmed and cut into strips of a desired size and shape customarily used 
for French fries. After cutting, the strips can be washed to remove 
surface starch. 
The preferred potato strips are known in the art as "shoestring" cuts. 
Shoestring potato strips are from about 3/16(0.18) to about 5/16 (0.3) 
inch (4.7-8 mm) square in cross-section and from about 2.5 to about 5 
inches (6.3-12.7 cm) in length. 
Another cut known in the art as "crinkle cut" strips usually average from 
about 0.3 to about 0.5 inch (8-13 mm) in cross-section and from about 2 to 
about 4 inches (5-10.2 cm) in length. 
Straight cut thick potato strips (also called regular-cut) are from about 
0.3 inch to about 0.5 inch (8 mm--13 mm) square in cross-section and about 
2.5 to about 5 inches (6.3-12.7 cm) in length. Larger potato strips of the 
type referred to as "steak fries" have a rectangular cross-section of 
about 0.5 inch to about 0.88 inch (13-22 mm) and about 2.5 to about 5.5 
inches (6.3-14 cm) in length. 
The potato strips are blanched according to conventional procedures known 
in the art. Blanching inactivates enzymes and removes excess free sugars 
from the surfaces of the cut strips. Blanching is done by immersion of the 
strips in hot water at a temperature of about 140.degree. F. (60.degree. 
C.) to about 200.degree. F. (93.degree. C.) for about 3 to about 20 
minutes. Alternatively, the blanching is with steam, at atmospheric 
pressure for about 2 to about 10 minutes. 
Following the blanching step, the potato strips can be treated according to 
conventional methods known in the art. For instance, the potato strips may 
be subjected to additional water immersion steps to further leach excess 
sugars or the strips may be treated with sodium acid pyrophosphate (SAPP), 
a chelating agent used to prevent discoloration of the strips. Dextrose 
(corn sugar) can also be applied to the surface of the strips in order to 
yield a desired level of brown color development during subsequent 
processing. Other treatments known in the art can also be used. 
After blanching and the optional treatments described above, the potato 
strips are drained and optionally dehydrated to reduce their moisture 
content. During dehydration of the strips the moisture content is 
typically reduced to a point at which the strips have lost from about 10% 
to about 30% of their initial weight, preferably about 15% to about 20% of 
their initial weight. Any of the conventional drying procedures used in 
the production of par-fried potato strips may be used, such as, for 
example, subjecting the potato strips to heated air at temperatures of 
from about 150.degree. F. (65.degree. C.) to about 350.degree. F. 
(176.degree. C.) for from about 5 to about 20 minutes. Microwave or 
radio-frequency drying may also be used. 
Generally the blanched potato strips are deep fried or immersed in oil, for 
example, at a temperature of from about 270.degree. F. (132.degree. C.) to 
about 385.degree. F. (196.degree. C). The frying time depends on the 
specific oil temperature, dimensions of the potato strips, the batch size, 
the volume of the frying kettle and the initial moisture content of the 
potato strips. This can be determined by one skilled in the art. Other 
techniques such as a heated oil spray that surrounds the potato strip with 
hot oil or frying in an oil foam can be used. The blanched potato strips 
are immersed in an edible oil for a time sufficient to produce par-fried 
potato strips having from about 38% to about 58% moisture. (Table I 
contains moisture and fat content ranges for preferred shoestringcuts used 
in the process of the present invention.) The parfried potato strips of 
the shoestring variety preferably have from about 40% to about 56% bulk 
moisture. Preferably these parfries have from about 42% to about 54%, and 
more preferably from about 44% to about 50% moisture. These parfries have 
from about 6% to about 25%, preferably from about 8% to about 22%, more 
preferably from about 10% to about 20%, and most preferably from about 12% 
to 18% fat 
Thicker cut potato strips (e.g., straight, regular-cuts or crinkle-cuts, 
"steak" fries) may be fried to slightly higher moisture contents. See 
Tables 2 and 3 for some details for these thicker potato strips. 
The par-fried potato strips can be commercially prepared by multiple 
processing steps (i.e., one par-fry and one freezing, or multiple 
par-fryings and multiple freezings). The preferred par-fried potato strips 
must have certain moisture and fat levels. 
The par-fried potato strips can be immediately enrobed with oil, or they 
can be cooled or frozen prior to enrobing. Chilling or freezing of the 
par-fries can be accomplished by methods known in the art. For example, 
the par-fried potato strips may be subjected to a blast of cold air at a 
temperature of less than about -20.degree. F. (-29.degree. C.), or the 
strips can be immersed in a liquid refrigerant, such as liquid nitrogen. 
Any conventional freezing process can be used. It is preferred that the 
par-fried potato strips be frozen quickly, i.e., in less than 20 minutes, 
preferably in less than 5 minutes after completion of the par-frying. 
A preferred method for preparing frozen oil-enrobed prebake fries intended 
for oven finishing by the process of this application comprises peeling, 
trimming and cutting raw potatoes into strips, blanching, and reducing the 
moisture of the potato strips to not less than about 60% via either oven 
drying or parfrying. The potato strips are then immersed in oil at a 
temperature of from about 270.degree. F. (132.degree. C.) to about 
335.degree. F. (196.degree. C.) for a time sufficient to further reduce 
the moisture of the strips to a final moisture content of from about 38% 
to about 58%. In order to ensure that the oven-finished French fry 
develops an outer crust similar to that of a deep fried French fry, it is 
necessary to coat (enrobe) the surface of the par-fried potato strips with 
an edible fat to yield oil-enrobed prebake fries. The surface coating can 
be applied immediately after removal of the par-fried potatoes from the 
fryer or the coating can be applied to frozen, chilled, or room 
temperature par-fried potato strips. The parfried potato strips are 
enrobed with a coating of oil on the surface (.about.2-15% by weight of 
the prebake fries) by immersion in a liquid oil or by spraying oil onto 
the surface or tumbling with oil. The oil-enrobed prebake fries are frozen 
and stored at a temperature of about 0.degree. F. (-18.degree. C.). The 
frozen oil-enrobed prebake fries are stable at 0.degree. F. (-18.degree. 
C.) for at least 3 months. When cooked in an oven by the present process, 
the finished French fries have improved flavor over conventional 
oven-cooked fries. 
While not being bound to a theory, it is theorized that the enrobing oil 
helps prevent rapid migration of moisture from the interior of the potato 
strip during baking, thereby resulting in dehydration and crispening of 
the crust region. Typically the enrobing/coating oil is from about 2% to 
about 15% by weight of the par-fried potato strips, preferably from about 
3% to about 12%, and more preferably an amount of from about 4% to about 
10%. Any edible oil can be used. 
The fat compositions used to coat or enrobe the par-fried potato strips can 
be applied to the surface of the potato strips by immersion, dipping, 
spraying, blowing, pouring, pan coating (e.g., in a revolving pan), tumble 
coating, rolling around in a container of a fat composition, falling film 
methods, enrobing, curtain coating, etc. Preferably the edible liquefied 
fat is applied in a substantially uniform coating by spraying the liquid 
fat onto the surface of the par-fried potato strips or by dipping the 
par-fried potato strips into the liquid fat. The coating may be continuous 
or discontinuous so long as it is uniformly distributed. 
Specifically, the following oil spray technique can be used. The coating 
oil is maintained at a temperature of from about 70.degree. F. (21.degree. 
C.) to about 200.degree. F. (93.degree. C.), preferably from about 
100.degree. F. (37.degree. C.) to about 180.degree.F. (82.degree. C.) and 
more preferably from about 120.degree. F. (48.degree. C.) to about 
160.degree. F. (71.degree. C.). Spray nozzles are arranged to apply the 
oil evenly over the parfries. The oil can be atomized during the spraying 
or sprayed in fine droplets. The parfried potato strips are arranged in a 
single layer or are tumbled during spray application of the oil. 
The surface oil coating can also be applied via an immersion or dipping 
technique. For example, the par-fried potato strips are frozen and 
equilibrated at 0.degree. F. (-18.degree. C.). The frozen par-fried strips 
are immersed rapidly (e.g. 1-3 seconds) into oil at a temperature of about 
335.degree. F. (168.degree. C.) and then immediately re-frozen by 
immersion in liquid nitrogen. This type of enrobing process adds a coating 
of oil onto the surface of the par-fried potato strips sufficient to 
increase the weight of the strips by about 2% to about 15%. 
In the process of the present invention it is important to maintain the fat 
in a substantially liquid state to allow the application of a sufficient 
and uniform coating. The application of the fat or oil before oven 
finishing is critical to providing a product with the texture of a 
conventional deep fried French fry. 
The oil-enrobed prebake fries (shoestring-cut), typically comprise from 
about 34% to about 54% moisture. Preferably the prebake fries have a 
moisture content of from about 36% to about 52%, more preferably from 
about 38% to about 50%, and even more preferably from about 40% to about 
48%. Additionally the prebake fries preferably comprise from about 8% to 
about 30% fat, wherein the level of surface fat is from about 2% to about 
15% by weight of the fries. The prebake fries preferably comprise from 
about 10% to about 28%, more preferably from about 12% to about 26%, and 
even more preferably from about 16% to about 24% fat. Some of the oil on 
the prebake fries will be lost in the baking process. Thicker cut prebake 
fries, may have slightly different moisture and fat contents. See Tables 
1-3 for a summary of the prebake fries properties. 
TABLE 1 
______________________________________ 
Shoestring-cuts (3/16"-5/16" cross section) 
Parfried Potato 
Oil-Enrobed Pre- 
Oven-Finished 
Strips bake Fries 
French Fries 
______________________________________ 
Moisture Range: 
38-58% H.sub.2 O 
34-54% H.sub.2 O 
32-46% 
H.sub.2 O 
Preferred: 
40-56% 
H.sub.2 O 
36-52% 
H.sub.2 O 
33-44% 
H.sub.2 O 
More Preferred: 
42-54% 
H.sub.2 O 
38-50% 
H.sub.2 O 
34-40% 
H.sub.2 O 
44-50% 
H.sub.2 O 
40-48% 
H.sub.2 O 
Fat Range: 
Fat25% Fat-30% 
12-25% 
Fat 
Preferred: 
Fat-22% 
10-28% 
Fat Fat3-23% 
More Preferred: 
10-20% 
Fat 12-26% 
Fat Fat4-20% 
12-18% 
Fat 16-24% 
Fat 
______________________________________ 
TABLE 2 
______________________________________ 
Regular-cut and Crinkle-cut (5/16"-1/2" cross section 
Parfried Potato 
Oil-Enrobed Pre- 
Oven-Finished 
Strips bake Fries 
French Fries 
______________________________________ 
Moisture Range: 
40-60% H.sub.2 O 
36-56% H.sub.2 O 
35-50% 
H.sub.2 O 
Preferred: 
44-56% 
H.sub.2 O 
40-52% 
H.sub.2 O 
38-48% 
H.sub.2 O 
More Preferred: 
46-54% 
H.sub.2 O 
42-50% 
H.sub.2 O 
40-46% 
H.sub.2 O 
Fat Range: 
Fat22% Fat28% 
Fat0-22% 
Preferred: 
Fat20% 10-24% 
Fat Fat1-20% 
More Preferred: 
10-18% 
Fat 14-20% 
Fat Fat2-18% 
______________________________________ 
TABLE 3 
______________________________________ 
Steak Fries (1/2"-7/8" cross section) 
Parfried Potato 
Oil-Enrobed Pre- 
Oven-Finished 
Strips bake Fries 
French Fries 
______________________________________ 
Moisture Range: 
42-62% H.sub.2 O 
38-58% H.sub.2 O 
38-53% 
H.sub.2 O 
Preferred: 
46-58% 
H.sub.2 O 
42-54% 
H.sub.2 O 
40-50% 
H.sub.2 O 
More Preferred: 
48-56% 
H.sub.2 O 
44-52% 
H.sub.2 O 
42-48% 
H.sub.2 O 
Fat Range: 
4-20% Fat 6-24% 
Fat Fat8-20% 
Preferred: 
Fat-18% 
8-20% 
Fat Fat9-18% 
More Preferred: 
8-16% 
Fat 10-18% 
Fat Fat0-16% 
______________________________________ 
Optional Freezing Step 
After coating the surface of the par-fries, the oil-enrobed prebake fries 
can optionally be frozen, packaged and stored for subsequent use. Typical 
frozen storage temperatures ranges from about -20.degree. F. (-29.degree. 
C.) to about 10.degree. F. (-12.degree. C.). Freezing the oil-enrobed 
prebake fries can be accomplished by methods known in the art. 
Specifically, the strips can be contacted with a liquid refrigerant at a 
temperature below 0.degree. F. (-18.degree. C.), preferably below 
-20.degree. F. (-29.degree. C.) to freeze the potato strip. It is 
essential that the surface of the strip be frozen, but the entire potato 
strip can also be frozen. The preferred liquid refrigerants are liquid 
fluorocarbons and liquid nitrogen. The oil-enrobed prebake fries can be 
dipped in a pool of the refrigerant, or sprayed with a liquid refrigerant 
or contacted with a gaseous refrigerants. The time required to achieve the 
desired degree of freezing will vary depending on such factors as the 
temperature of the refrigerant, the size of the potato strips, the 
temperature of the potato strips, etc. The freezing can either be a 
surface freeze or a total freeze. For example, the oil-enrobed prebake 
fries can be subjected to a current of cold air at a temperature below 
0.degree. F. (-18.degree. C.). A convenient method is to use a 
conventional blast freezer or a high velocity current of air where the 
fries are subjected to a blast of cold air at a temperature of less than 
or equal to about -20.degree. F. (-29.degree. C.). Alternatively, the 
fries can be placed in a freezer at -10.degree. F. (-23.degree. C.). 
Edible Fats and Oils 
The fats used herein to fry and enrobe the fries are selected from the 
group consisting of triglycerides, non-digestible fats or reduced calorie 
fats and mixtures thereof. Preferred triglycerides include soybean oil, 
corn oil, cottonseed oil, sunflower oil, palm oil, coconut oil, canola 
oil, fish oil, tallow, peanut oil, medium chain triglycerides, structured 
triglycerides containing a combination of short or medium chain fatty 
acids and long chain fatty acids (e.g. Caprenin-like) and the like which 
may have been partially or completely hydrogenated or otherwise modified. 
Non-toxic fatty materials having properties similar to triglycerides, 
herein referred to as fat substitutes can be partially or fully 
indigestible. Reduced calorie fats and edible non-digestible fats, oils or 
fat substitutes can also be used. 
A variety of edible fats and oils may be used to coat the surface and to 
fry the par-fried potato strips. Edible fats and oils suitable for use 
include but are not limited to those listed above. If desired the oils may 
be conditioned or flavored, see Flavored Vegetable Oils as a Substitute 
for Beef Tallow in Deep Frying Applications, Food Technology, pp. 90-94 
(1989) and U.S. Pat. No. 5,104,678 (Yang et al.). 
Preferably the edible fat or oil used to fry and enrobe the parfried potato 
strips has a free fatty acid level of about 0.8% or less. 
The edible oils used for frying or enrobing the par-fried potato strips can 
be a 100% natural oil or a 100% synthetic oil. The oil may be partially or 
completely hydrogenated or modified otherwise. The preferred fat 
substitute are fatty materials having properties similar to triglycerides 
such as sucrose polyesters. OLEAN.TM. is a preferred fat substitute. It is 
made by The Procter and Gamble Company. Reduced calorie fats, polyol fatty 
acid polyesters, and diversely esterified polyol polyesters or 
combinations of regular fats and fat substitutes can also be used herein. 
These preferred nondigestible fat or oil substitute compositions are 
described in the literature, for example, in Young; U.S. Pat. No. 
5,085,884; Issued Feb. 4, 1992, and U.S. Pat. No. 5,422,131, issued Jun. 
6, 1995 to Elsen et al. 
One reduced calorie fat that has been found to be useful comprises a fairly 
high level (e.g., at least about 85%) of combined MML and MLM 
triglycerides, where M is typically a mixture of C.sub.8 -C.sub.10 
saturated fatty acids and L is predominantly behenic acid, but can be 
C.sub.20 -C.sub.24. See U.S. Pat. No. 4,888,196 to Ehrman et al., issued 
Dec. 9, 1989 and U.S. Pat. No. 5,288,512 issued to Seiden, Feb. 22, 1994 
for the synthesis and more detailed description of these reduced calorie 
fats. 
By "polyol" is meant a polyhydric alcohol containing at least 4, preferably 
from 4 to 11 hydroxyl groups. Polyols include sugars (i.e., 
monosaccharides, disaccharides, and trisaccharides), sugar alcohols, other 
sugar derivatives (i.e., alkyl glucosides), polyglycerols such as 
diglycerol and triglycerol, pentaerythritol and polyvinyl alcohols. 
Specific examples of suitable sugars, sugar alcohols and sugar derivatives 
include xylose, arabinose, ribose, xylitol, erythritol, glucose, methyl 
glucoside, mannose, galactose, fructose, sorbitol, maltose, lactose, 
sucrose, raffinose, and maltotriose. 
By "polyol fatty acid polyester" is meant a polyol having at least 4 fatty 
acid ester groups. Polyol fatty acid esters that contain 3 or less fatty 
acid ester groups are generally digested in, and the products of digestion 
are absorbed from, the intestinal tract much in the manner of ordinary 
triglyceride fats or oils, whereas those polyol fatty acid esters 
containing 4 or more fatty acid ester groups are substantially 
non-digestible and consequently non-absorbable by the human body. It is 
not necessary that all of the hydroxyl groups of the polyol be esterified, 
but it is preferable that disaccharide molecules contain no more than 3 
unesterified hydroxyl groups for the purpose of being non-digestible. 
Typically, substantially all, e.g., at least about 85%, of the hydroxyl 
groups of the polyol are esterified. In the case of sucrose polyesters, 
typically from about 7 to 8 of the hydroxyl groups of the polyol are 
esterified. 
The polyol fatty acid esters typically contain fatty acid radicals 
typically having at least 4 carbon atoms and up to 26 carbon atoms. These 
fatty acid radicals can be derived from naturally occurring or synthetic 
fatty acids. The fatty acid radicals can be saturated or unsaturated, 
including positional or geometric isomers, e.g., cis- or trans- isomers, 
and can be the same for all ester groups, or can be mixtures of different 
fatty acids. 
Liquid non-digestible oils have a complete melting point below about 
37.degree. C. include liquid polyol fatty acid polyesters (see Jandacek; 
U.S. Pat. No. 4,005,195; Issued Jan. 25, 1977); liquid esters of 
tricarballylic acids (see Hamm; U.S. Pat. No. 4,508,746; Issued Apr. 2, 
1985); liquid diesters of dicarboxylic acids such as derivatives of 
malonic and succinic acid (see Fulcher; U.S. Pat. No. 4,582,927; Issued 
Apr. 15, 1986); liquid triglycerides of alpha-branched chain carboxylic 
acids (see Whyte; U.S. Pat. No. 3,579,548; Issued May 18, 1971); liquid 
ethers and ether esters containing the neopentyl moiety (see Minich; U.S. 
Pat. No. 2,962,419; Issued Nov. 29, 1960); liquid fatty polyethers of 
polyglycerol (See Hunter et al; U.S. Pat. No. 3,932,532; Issued Jan. 13, 
1976); liquid alkyl glycoside fatty acid polyesters (see Meyer et al; U.S. 
Pat. No. 4,840,815; Issued Jun. 20, 1989); liquid polyesters of two ether 
linked hydroxypolycarboxylic acids (e.g., citric or isocitric acid) (see 
Huhn et al; U.S. Pat. No. 4,888,195; Issued Dec. 19, 1988); liquid esters 
of epoxide-extended polyols (see White et al; U.S. Pat. No. 4,861,613; 
Issued Aug. 29, 1989); all of which are incorporated herein by reference, 
as well as liquid polydimethyl siloxanes (e.g., Fluid Silicones available 
from Dow Coming). 
Additional Ingredients 
Flavoring agents, such as salt, pepper, butter, onion, or garlic may be 
added to the frying and/or enrobing oil to enhance the flavor or modify 
the flavor to any desired taste. One skilled in the art will readily 
appreciate that the aforementioned listing of flavoring agents is in no 
way exhaustive, but is merely suggestive of the wide range of additives 
which are suitable for use in the practice of the present invention. 
Other ingredients known in the art may also be added to the edible fats and 
oils used to coat the surface and fry the par-fried potato strips, 
including antioxidants such as TBHQ, chelating agents such as citric acid, 
and anti foaming agents such as dimethylpolysiloxane. 
While specific preferred processing steps have been disclosed to facilitate 
an understanding of the invention, the functional equivalents can be 
substituted or additional ingredients may be added without departing from 
the spirit or essential characteristics of the present invention. 
Accordingly, the disclosed embodiments are considered in all respects to 
be illustrative and not restrictive. Typical parfries, prebake fries and 
oven-finished fries have the properties outlined in Tables 1, 2 and 3 
above. 
The oil enrobed prebake fries are oven finished. Table 4 contains suitable 
baking times and temperatures used in the process of this invention for 
oven finishing the oil enrobed prebake fries. 
TABLE 4 
______________________________________ 
Baking Times and Temperatures 
Range #1 
Range #2 Range #3 Range #4 
______________________________________ 
Bake Time (minutes) 
0.75-15 1-10 1.5-5 2-3 
Temperature (.degree. F.) 
325-800 350-500 
375-475 
400-450 
Temperature (.degree. C.) 
162-426 176-260 190-246 
204-232 
______________________________________ 
The Oven 
Some examples of suitable ovens are: forced air convection ovens, 
combination infrared radiation and convection ovens, radiant heat ovens, 
toasters, toaster ovens, high velocity air impingement ovens, combination 
microwave-convection ovens, and infrared radiation ovens. Rotating drum 
convection ovens or combination infrared-convection ovens can also be 
used. The baking times will vary somewhat depending on the type of oven 
and the baking temperature. When toasters are used to finish bake the oil 
enrobed prebake fries, multiple heating cycles may be required. 
Conventional microwave ovens can be used for warming frozen prebake fries 
prior to placing them into another suitable oven for finishing but they do 
not heat the surface to a high enough temperature to cause it to get crisp 
unless a susceptor or special container is used. The names of suppliers 
and models of some suitable ovens are: 
1. Forced Air Convection Ovens 
A. Wells Manufacturing Co., Verdi, Nev., Model No. M42003S (Convection 
oven). 
B. U.S. Range, Gardena, Calif., Model No. BG-100 (Convection Oven). 
C. Blodgett Oven Co., Burlington, Vt, Model No. DFG-100 Convection Oven. 
2. Hot Air Impingement Ovens 
A. Lincoln Foodservice Products, Fort Wayne, Ind. (Impinger I oven). 
B. Middleby Marshall, Elgin, Ill.; Model No. PS200, (Double Impingement 
Oven). 
C. Blodgett Oven Co., Burlington, Vt.; Model No. MT2136; (Mastertherm 
Conveyor Oven) 
3. Infrared Ovens 
Quadlux, Inc., Fremont, Calif.; FlashBake Oven Model No. FB5000 
4. Rotating Drum Convection Ovens 
Toastmaster, Elgin, Ill., RoFry, Model RF200 
5. Microwave-Convection Combination 
Amana Refrigeration, Inc., Amana, Iowa; Model No. CMA2000; Convection 
Express Oven 
6. Toast-R Oven 
Black & Decker, Shelton, Conn., Model No. TRO200TY. 
In one preferred embodiment, the oil-enrobed prebake fries are preferably 
baked as a single layer on an open mesh metal oven tray or baskel An 
essentially single layer of fries allows at least a majority of the fries 
to be in direct contact with the oven tray. Preferably, frozen oil-enrobed 
fries are first baked on a metal wire mesh oven rack or tray for about 0.5 
to about 2 minutes. Then they are transferred to a solid metal oven tray 
and baked until they are done. This second baking is preferably about 1 to 
3 minutes. Generally, prior art frozen potato strips are baked for about 
10 to 20 minutes. Faster oven finishing time is one of the primary 
benefits of this invention. A continuous baking process using metal 
conveyors can also be used herein to bake the enrobed prebake fries. 
The specific oven process conditions used for preparing the oven-finished 
French fries will depend upon the quantity of prebake fries being baked, 
their initial temperature, the type of oven, and the thermal properties of 
the oil-enrobed prebake fries. Of particular importance are the thermal 
conductivity of the low-moisture crust region, the thermal conductivity of 
the high-moisture interior starch-matrix core, and the surface heat 
transfer coefficient of the prebake fry. In general, higher thermal 
conductivities and higher surface heat transfer coefficients will result 
in more rapid transfer of heat from the oven to and through the fry, 
resulting in reduced cooking time. Since it is an object of the present 
invention to provide a fast food process for quickly finishing frozen 
par-fries in an oven, these properties are of particular importance. The 
desirable thermal conductivities at oven temperature of the low moisture 
crust region in the prebake fry are from about 0.1 to about 0.3 
watt/m-.degree. C. The desirable thermal conductivities at oven 
temperature of the high moisture core region in the prebake fry are from 
about 0.4 to about 0.7 watts/m-.degree. C. The thermal conductivity of the 
crust region can be adjusted to the desirable range by controlling the 
level of moisture and fat in the crust. 
The surface heat transfer coefficient of the prebake fry is a function of 
forced air velocity, air temperature, and the nature of the oil film at 
the surface of the fry. Higher surface heat transfer coefficients are 
desirable since this will generally lead to faster cooking time, and the 
formation of more distinct and crisp low moisture crust region in the 
oven-finished French fry. The desirable surface heat transfer coefficients 
at oven temperature of the prebake fry in the oven are from about 50 to 
about 400 watts/m.sup.2- .degree. C. The surface heat transfer coefficient 
is increased as a consequence of enrobing the parfried potato strips with 
an edible fat or oil, which increases the conduction of heat from the 
surrounding air to the fry surface. The surface of the prebake fry may 
also be modified to improve the absorption of radiant heat from the oven. 
A typical method of accomplishing this would be to alter the color, 
porosity, and or reflectivity of the surface. Increasing the velocity of 
the oven air at the surface of the fry will also increase the surface heat 
transfer coefficient The oven air velocity should be high enough to 
achieve a satisfactory heat transfer coefficient, but not so high as to 
strip away the enrobing oil on the surface. 
High quality French fries are golden brown in color and have crisp crusts 
and moist interiors. The ideal oven-furnished French fries made by the 
process described herein have the color, texture, mouthfeel and taste of 
high quality deep fat fried French fries, e.g. McDonald's.TM. fries. 
High Quality Oven-Finished Fries 
The process of the present invention provides superior oven-finished French 
fries. Table 5 contains a detailed description of high quality 
oven-finished shoestring-cut French fries made by the process of the 
present invention. These superior oven-finished shoestring-cut French 
fries have: a bulk moisture of from about 32% to about 46%; preferably 33% 
to 44%, more preferably 34% to 40% bulk moisture. They also have a total 
fat content of from about 12% to about 25%, preferably 13% to 23%, more 
preferably about 14% to 20% total fat. The preferred oven-finished 
shoestring French fries have an internal moisture content of from about 
55% to 80%, preferably about 60% to 77%, more preferably about 63% to 
about 75% moisture. They have a surface water activity (Surface Aw) equal 
to or less than about 0.55, preferably from about 0.1 to about 0.52, more 
preferably from about 0.15 to about 0.5, and even more preferably 
0.2-0.45. The texture of fries and baked food products is known to be 
related in part to the water activity (Aw) of the product, Crisp textures 
are generally associated with Aw values of less than about 0.55. The 
preferred oven-finished shoestring French fries have a Texture Value of 
about 200 or greater, preferably about 210 to 1000, more preferably 220 to 
600, and even more preferably 240 to 500. 
TABLE 5 
______________________________________ 
HIGH QUALITY OVEN-FINISHED 
SHOESTRING-CUT FRENCH FRIES* 
Range Preferred Range 
More Preferred 
______________________________________ 
Bulk Moisture: 
32-46% 33-44% 34-40% 
Total Fat: 13-23% 14-20% 
Internal Moisture.dagger-dbl.: 
55-80% 60-77% 63-75% 
Surface Aw: 
0.1-0.52 55 
0.2-0.45 
FFTV**: 210-1000 .200 
240-500 
______________________________________ 
*High quaility deepfat fried French fries and the ovenfinished French 
fries of this process invention have all these qualities. The prior art 
ovenfinished French fries do not. 
**French Fry Texture Value (Texture Value) 
.dagger-dbl.Preferred 
FNT *High quality deep-fat fried French fries and the oven-finished French 
fries of this process invention have all these qualities. The prior art 
oven-finished French fries do not. 
FNT **French Fry Texture Value (Texture Value) 
FNT .dagger-dbl. Preferred 
The French Fry Texture Value is measured by a compression test, which is 
described in detail in the following section on analytical test methods. 
The French Fry Texture Value Test yields two measurements that 
characterize the textural properties of French fries, average Maximum 
Force (grams) and average Area (gram.times.sec). Both of these texture 
measurements correlate to the crispness of French fries and either one may 
be designated as the Texture Value. 
As described above and in Tables 5-7, high quality oven-finished French 
fries are characterized by a Texture Value of about 200 or greater, which 
means that at least one of the textural parameters (Maximum Force or Area) 
has a value of about 200 or greater. The most highly preferred 
oven-finished French fries prepared by the process described herein are 
further characterized by a ratio of the Area (gram.times.sec) to the 
Maximum Force (grams) of at least 1.0, preferably 1.04 or greater, more 
preferably 1.08 or greater, even more preferably 1.12 or greater, and most 
preferably 1.16 or greater. The high quality oven-finished French fries 
made by the process described herein, as well as deep fat fried French 
fries (e.g., McDonald's.TM. fries), are characterized by a Texture Value 
of about 200 or greater and a ratio of the Area to Maximum Force of at 
least 1.0. For illustration, following are textural data generated for 
multiple batches of McDonald's.TM. deep fried French fries: 
______________________________________ 
Avg. Maximum Avg. Area Ratio of Area 
Batch # Force (grams) 
(gram .times. sec) 
to Max Force 
______________________________________ 
1-10 227 286 1.26 
11-20 348 431 
1.24 
21-30 323 403 
1.25 
31-40 266 335 
1.26 
41-50 330 415 
1.26 
51-60 243 294 
1.21 
______________________________________ 
Thicker-cut oven-finished French fries (e.g., regular-cut, crinkle-cut and 
steak fries) have different moisture and fat ranges. See Tables 6-7 for 
summaries. 
Table 6 contains a detailed description of high quality oven-finished 
regular or straight cuts and crinkle cut French fries made by the process 
of the present invention. 
TABLE 6 
______________________________________ 
HIGH QUALITY OVEN-FINISHED REGULAR CUTS 
Range Preferred Range 
More Preferred 
______________________________________ 
Bulk Moisture 
35-50% 38-48% 40-46% 
Total Fat: 11-20%% 12-18% 
Internal Moisture.dagger-dbl.: 
55-80% 60-77% 63-75% 
Surface Aw: 
0.1-0.52 
0.2-0.45 
Texture Value**: 
.ltoreq.200 
210-1000 
240-500 
______________________________________ 
Table 7 contains a detailed description of high quality oven-finished steak 
fries made by the process of the present invention. 
TABLE 7 
______________________________________ 
STEAK FRIES 
Range Preferred Range 
More Preferred 
______________________________________ 
Bulk Moisture: 
38-53% 40-50% 42-48% 
Total Fat: 9-18% 
10-16% 
Internal Moisture: 
55-80% 
60-77% 
63-75% 
Surface Aw: 
.ltoreq.0.55 
0.1-0.52 
0.2-0.45 
Texture Value**: 
.gtoreq.200 
210-1000 
240-500 
______________________________________ 
The oven-finished French fries made by the process descnbed herein can also 
be characterized, by Nuclear Magnetic Resonance (NMR) imaging, which 
provides a cross-sectional image depicting the moisture and fat 
distribution within the fries. The high quality oven-finished French fries 
made by the process described herein, as well as deep fat fried French 
fries (e.g., McDonald's.TM. fries), are characterized by NMR images that 
reveal a high moisture internal core surrounded by a low moisture crust 
region that contains the fat. 
ANALYTICAL TEST METHODS 
A number of parameters are used to characterize elements of the parfried 
potato strips, oil-enrobed prebake fries, and oven-finished French fries 
of the present invention. They are quantified by particular experimental 
analytical procedures. Each of these procedures is described in detail as 
follows: 
Bulk Moisture Content Test 
Moisture content of par-fried potato strips, oil enrobed prebake fries and 
finished French fries is determined by a forced air oven method as 
follows: 
1. Uniformly grind up a representative sample of potato strips or French 
fries in a blender or conventional food processor. 
2. Accurately weigh approximately 5 grams of ground sample (weight "A") 
into a previously tared metal pan or dish. 
3. Place the metal dish containing the sample in a forced air convection 
oven at 105.degree. C. for 2 hours. 
4. After 2 hours, remove the metal dish containing the dried sample and 
allow to cool to room temperature in a desiccator over a desiccant such as 
anhydrous calcium sulfate. 
5. Re-weigh the dish containing the dried sample and calculate the weight 
of the dried sample (weight "B") by subtracting the dish tare weight. 
6. Calculate the percent moisture of the sample as follows: 
EQU % Moisture=[(A-B)/(A)].times.100. 
French Fry Texture Value Test 
The Texture Value of finished French fries, which correlates with crispness 
of the fries, is measured with a TA-XT2 Texture Analyzer (version 05.16 
equipped with 25-1 load cell, Texture Technologies Corp., Scarsdale, 
N.Y.). The Texture Analyzer is linked to a standard personal computer 
(e.g. IBM 433DX) that records the data via a software program called XTRA 
Dimension (version 3.7H, Texture Technologies Corp., Scarsdale, N.Y.). 
The Texture Analyzer is configured with a rectangular, blunt steel plate 
probe (2.5-3.0 mm thickness, 70 mm width, 90 mm length) that is fastened 
vertically to the main arm. A "Compression Test" on a single French fry 
will be run to generate a plot of Force (grams) vs. Time (sec), from which 
the Texture Value is obtained. 
______________________________________ 
Procedure for Set-up and Calibration of the Texture Analyzer 
______________________________________ 
1. Set-up the Texture Analyzer as follows: 
Mode: Measure Force in Compression 
Option: Return to Start 
Force Units: Grams 
Time Units: Seconds 
Distance Format: 
Strain 
Pre-Test Speed: 
2.0 mm/sec 
Probe Test Speed: 
1.0 mm/sec 
Post-Test Speed: 
10 mm/sec 
Strain: 85.0% 
Trigger Type: Auto 10 
2. Set the texture method as follows: 
Graph Type: Force vs. Time 
Auto-Scaling: Off 
Force Scaling Max: 
5000 grams 
Force Scaling Min: 
0 grams 
Peak Confirmation: 
On 
Force Threshold: 
20 grams 
File Type: Lotus 1-2-3 
Display and Export: Plotted points 
Acquisition Rate: 
200 pps 
Force Units: Grams 
Contact Area: 1.00 mm.sup.2 
Contact Force: 
5.0 grams 
______________________________________ 
3. Calibrate the force by placing a 5 kg weight on the calibration platform 
and press the "calibrate" button on the Texture Analyzer key pad. 
4. Calibrate the probe distance from the base plate with a probe starting 
distance from the plate of 10 mm for shoestring-cut fries (increase probe 
starting distance to 15 mm for thick-cut or steak fries). Ensure that the 
bottom surface of the probe is parallel to the surface of the base plate. 
Procedure for Sample Measurements 
1. Immediately following removal of finish-cooked French fries from a fryer 
(deep-fried) or oven (oven-baked), place the batch of fries under a heat 
lamp for 1 minute prior to beginning the texture analysis. The air 
temperature under the heat lamp is between about 130.degree. F. and about 
180.degree. F. (about 54.3.degree. C. to about 82.2.degree. C.). 
2. After the 1 minute hold time has elapsed, place a single French fry flat 
on the base plate of the Texture Analyzer (oriented perpendicular to the 
probe width). Initiate the Compression Test (1.0 mm/sec probe speed) while 
manually holding the ends of the French fry flush against the base plate. 
3. The resulting Force (grams) vs. Time (sec) data is saved for later 
analysis. Nine additional fry samples from the same batch are tested in an 
identical manner. The ten fry samples from each batch are selected 
randomly. Texture analysis of the ten fry samples should be completed 
within 3-4 minutes. (3-4 minutes after Step 1). 
4. Steps #1-#3 are repeated for each new batch of French fries. Generally, 
5 to 10 batches of each type of French fry are evaluated in this manner. 
Data Analysis 
1. The "Force vs. Time" plot for each individual French fry sample is 
evaluated for the following: 
* Maximum Force (grams) within the first 1/3 of the test. 
* Area (gram sec) under the curve within the first 1/3 of the test. (e.g. 
if the Compression Test requires 6 seconds to complete, the Maximum Force 
and Area are obtained from the 0-2 second time period). 
2. After analysis of the "Force vs. Time" data for all ten French fry 
samples selected from a given batch, the ten Maximum Force values are 
averaged and the ten Area values are averaged. A computer program written 
in Excel automates the task of analyzing the Force vs. Time data for each 
fry sample and averaging the Maximum Force and Area values for each batch 
of fries. 
3. Remaining batches of a particular French fry type are analyzed in a 
similar manner (5-10 batches are tested; 10 fries/batch are analyzed). The 
Maximum Force and Area values for each batch are then averaged to yield an 
overall average Maximum Force (grams) and Area (gram sec) for that 
particular fry type. 
4. For the purpose of this invention, either the overall average Maximum 
Force or Area may be designated as the French fry TEXTURE VALUE. Both 
texture measurements correlate to crispness of finished French fries. 
Determination of the Internal Moisture Content of French Fries 
Internal moisture content of finished French fries, i.e. moisture content 
of the interior starch matrix, is determined as follows: 
1. Immediately following removal of finish-cooked French fries from a fryer 
(deep-fried) or oven (oven-baked), immerse the fries in liquid N.sub.2 for 
20 seconds to completely freeze the products and stabilize the internal 
moisture distribution. 
2. Store the frozen French fries at about -112.degree. F. (-80.degree. C.) 
until analysis. 
3. Remove several fries from the freezer and place on a stainless steel 
tray. Allow the fries to warm slightly for several minutes at room 
temperature to facilitate removal of the crust. 
4. Carefully cut off the crust on one side of each frozen fry with a razor 
blade. Rotate the fries and repeat this procedure until the crust has been 
removed from all four sides. 
5. Collect the frozen interior starch matrix (white solidified material) 
and immediately place in a capped glass vial. Take care only to collect 
the interior starch matrix; do not include any crust remnants. 
6. Repeat steps #3-#5 until approximately 5 grams of frozen interior starch 
matrix is collected. This may require about 15-20 fries. 
7. Accurately weigh approximately 5 grams of the interior starch matrix 
(weight "A") into a previously tared metal pan or dish. 
8. Place the metal dish containing the interior starch matrix in a forced 
air convection oven at 105.degree. C. for 2 hours. 
9. After 2 hours, remove the metal dish containing the dried sample and 
allow to cool to room temperature in a desiccator over a desiccant such as 
anhydrous calcium sulfate. 
10. Re-weigh the dish containing the dried sample and calculate the weight 
of the dried sample (weight "B") by subtracting the dish tare weight. 
11. Calculate the percent moisture of the interior starch matrix as follows 
: 
EQU % internal moisture=[(A-B)/(A)].times.100 
Determination of the Surface Water Activity (Aw) of French Fries 
Surface Aw of finished French fries is determined as follows: 
1. Immediately following removal of finish-cooked French fries from a fryer 
(deep-fried) or oven (oven-baked), immerse the fries in liquid N.sub.2 for 
20 seconds to completely freeze the products and stabilize the internal 
moisture distribution. 
2. Store the frozen French fries at about -112.degree. F. (-80.degree. C.) 
until analysis. 
3. Transfer a bag of French fries (.about.0.5-1 lb.) from the -112.degree. 
F. (-80.degree. C.) freezer to a cooler containing dry ice; ensure the bag 
is thoroughly packed in dry ice in order to maintain the fries in a frozen 
state at low temperature. 
4. Remove one French fry at a time from the sample bag and rapidly scrape 
the surface of the fry with a single-edged razor blade. Collect the 
surface shavings onto a stainless steel tray and immediately transfer the 
shavings to a capped glass vial. 
Take care only to colect surface shavings from the outer crust region of 
the French fry; do not scrape so hard such that the crust region is 
penetrated and the interior starch matrix core is exposed. 
5. Repeat step #4 until approximately 0.3-0.7 gram of surface shavings is 
collected; this will require scraping about 10-20 frozen fries. 
6. Determine the water activity (Aw) of the surface shavings using a 
Rotronic Hygroskop Model DT relative humidity meter (Rotronic Instrument 
Corp., Huntington, N.Y.), as follows: 
a. Transfer the surface shavings to a plastic Aw dish (Rotronic Instrument 
Corp.). 
b. Immediately place the Aw dish containing the surface shavings into one 
of the humidity cells of the Hygroskop Model DT relative humidity meter 
and close the cell cover tightly. 
c. Allow the meter reading to stabilize (wait 1 hour or longer) before 
recording the reading and temperature. 
d. Convert the stabilized meter reading to % Relative Humidity (RH) using a 
previously prepared calibration graph (meter reading vs. % RH) prepared 
with the following RH standards: 
______________________________________ 
11% RH Saturated solution of Lithium Chloride (see Greenspan, L., 
1977, J. Res. Natl. Bur. Stand., Section A, 81A 89) 
35% RH Standard solution from Rotronic Instrument Corp. 
50% RH Standard solution from Rotronic Instrument Corp. 
65% RH Standard solution from Rotronic Instrument Corp. 
______________________________________ 
e. Convert % RH of the surface shavings to Surface Aw as follows: 
EQU Surface Aw=[% RH/100]. 
Total Fat Content Test 
Total fat content of par-fried potato strips, oil-enrobed prebake fries, 
and finished French fries is determined by a solvent extraction method as 
follows: 
Apparatus 
1. Soxtec HT6 extraction system; unit includes heating block and cooling 
condenser. 
2. Recirculating water bath for cooling condenser. 
3. Recirculating oil bath for heating block. 
4. Extraction beakers. 
5. Extraction thimbles, 26 mm (Fisher TC1522-0018). 
6. Nitrogen purging gas 
7. Vacuum drying oven 
8. Analytical balance (4 place) 
9. Dispensing pipette (50 ml) 
Materials 
1. Methylene chloride (Baker 9315-33) 
2. Boiling stones (Chemware PTFE Fisher 09-191-20) 
3. Silicone oil (Fisher TC1000-2779) 
4. Glass wool (Fisher 11-390) 
Procedure 
1. Uniformly grind a representative sample of potato strips or French fries 
in a blender or conventional food processor. 
2. Accurately weigh (to four places) a piece of glass wool (sufficient in 
size to contain sample pieces in the thimble) and the extraction thimble; 
record weight of thimble+glass wool (weight "A"). 
3. Load the ground sample into the thimble and cap the loaded thimble with 
the pre-weighed piece of glass wool. 
4. Accurately weigh (to four places) and record the weight of the ground 
sample, thimble,+glass wool (weight "B"). 
b 5. Place two or more boiling stones into an extraction beaker and weigh 
(to four places); record weight of extraction beaker+boiling stones 
(weight "C"). 
6. Place loaded thimbles on the extraction unit and raise the thimbles to 
rinse position. 
7. Pipette 50 ml of methylene chloride into each pre-weighed extraction 
beaker with boiling stones. 
8. Set oil heating bath to 110.degree. C. and water cooling bath to 
28.3.degree. C. and allow temperatures to equilibrate. 
9. Lower the loaded thimbles into the extraction beaker containing the 
solvent and allow to boil in the solvent for 60 minutes with the 
condenser's pet cock in the open position. 
10. Raise the thimbles to the rinsing position and rinse for 60 minutes. 
11. Turn the condenser's pet cock to the closed position and allow the 
solvent to evaporate for 60 minutes. Turn the nitrogen purging gas on to 
aid the evaporation. 
12. Transfer the beaker to a vacuum oven, pre-warmed to 120.degree. C., for 
30 minutes at full vacuum (about 30 mm Hg pressure or less). 
13. Allow the beaker to cool to room temperature and weigh (to four 
places); record the weight of the beaker+boiling stones+extracted fat 
(weight "D"). 
14. Calculate percent total fat as follows: 
EQU % Fat=[(D-C)/(B-A)].times.100

EXAMPLES 
The following are non limiting examples of the present invention. 
Example 1 
High quality frozen commercially available shoestring cut par-fries (e.g., 
Simplot Par Fries, J. R. Simplot Co., Caldwell, Id.) are acceptable 
starting products. The par-fries have a moisture content of about 64%. 
About 1 lb. of the par-fries are deep fried in a 45 lb. oil capacity fryer 
containing Primex 108 vegetable oil (blend of partially hydrogenated 
soybean oil and corn oil; available from the Procter & Gamble Co.) for 
about 3 minutes at a temperature of about 290.degree. F. (144.degree. C.). 
The par-fries are then immediately frozen by immersion in liquid nitrogen 
for about 20 seconds. The moisture content of the resulting par-fry is 
about 48% and the fat content is about 14%. Immediately after being frozen 
the par-fries are enrobed with oil by immersing in liquid vegetable oil 
(conditioned Primex 108) having a temperature of about 335.degree. F. 
(-168.degree. C.) for about 1-3 seconds. The resulting oil-enrobed prebake 
fries are again frozen by immersion in liquid nitrogen. The frozen prebake 
fries are packed into tightly sealed packages and stored at normal freezer 
temperatures of approximately 0.degree. F. (-18.degree. C.) to about 
-20.degree. F. (-29.degree. C.). The prebake fries contain about 10% 
surface fat by weight of the fries. The total fat level is about 22% and 
the bulk moisture level is about 43%. 
About 128 grams of the above frozen prebake fries are placed on an open 
wire mesh oven tray in a single layer and then baked at a temperature of 
about 400.degree. F. (204.degree. C.) in a forced air convection oven 
(Wells Manufacturing Co.; Model No. M42003S) for about 1 minute. Then the 
fries are transferred to a solid stainless steel oven tray in a single 
layer and baked an additional 1.5 minutes. The resulting French fries 
have: a bulk moisture of about 38%, a fat content of about 18%; an 
internal moisture content of about 67%, a Surface Aw of about 0.3, and a 
French Fry Texture Value of about 240 (Max. Force=205g; Area=243 
g.times.sec.; Ratio of Area to Max. Force=1.19). The oven-finished French 
fries are virtually identical in flavor and texture to deep fried French 
fries, e.g., from McDonald's. 
Example 2 
Commercially available frozen shoestring-cut par-fried potato strips (e.g. 
Payette Farms Shoestring Frozen Potatoes, J. R. Simplot Co., Caldwell, 
Id.) are obtained for additional processing. The parfries have a bulk 
moisture content of about 70%. 
The above-mentioned par-fried potato strips are further processed. First, 
about 1 lb. of the frozen potato strips are fried in a 45 lb. fryer 
containing Primex 108 vegetable oil (blend of partially hydrogenated 
soybean oil and corn oil; available from The Procter & Gamble Co.) for 3 
minutes at a temperature of about 335.degree. F. (.about.168.degree. C.). 
The par-fried potato strips are then frozen in liquid nitrogen for 20 
seconds and stored at -20.degree. F. (-29.degree. C.). The par-fried 
potato strips have a moisture content of about 44% and a fat content of 
about 14%. The frozen par-fried potato strips are enrobed with oil by 
immersing in liquid vegetable oil (conditioned Primex 108) having a 
temperature of about 335.degree. F. (.about.168.degree. C.) for about 1-3 
seconds. The resulting oil-enrobed prebake fries are then frozen by 
immersion in liquid nitrogen for about 20 seconds. About 10% fat is on the 
surface of the frozen oil-enrobed prebake fries. The oil-enrobed prebake 
fries have about 40% moisture content and about 23% fat. 
About 128 grams of the frozen prebake fries are placed on an open wire mesh 
oven tray in a single layer and then baked at a temperature of about 
400.degree. F. (.about.204.degree. C.) in a forced air convection oven 
(Wells Manufacturing Company, Verdi, Nev. Model No. M42003S) for about 1 
minute. Then the fries are transferred to a solid stainless steel oven 
tray in a single layer and baked an additional 1.25 minutes. The resulting 
French fries have: a bulk moisture of about 38%; a total fat content of 
about 19%; an internal moisture content of about 68%; a Surface Aw of 
about 0.4, and a French Fry Texture Value of about 260 (Max. Force=239 g; 
Area=260 g.times.sec.; Ratio of Area to Max. Force=1.09). The 
oven-finished French fries are virtually identical in taste and texture to 
high-quality deep fried French fries. 
Example 3 
The commercially available frozen shoestring-cut parfries of Example 2, 
which have a bulk moisture content of about 70%, are used as the starting 
material. 
The above-mentioned par-fried potato strips are further processed. First, 
about 1 lb. the frozen potato strips are fried by immersing in Primex 108 
vegetable oil (blend of partially hydrogenated soybean oil and corn oil; 
available from The Procter & Gamble Co.) for 3 minutes at a temperature of 
about 335.degree. F. (.about.168.degree. C.). The par-fried potato strips 
are then frozen in liquid nitrogen for 20 seconds and stored at 0.degree. 
F. (-18.degree. C.). The frozen par-fried potato strips have a moisture 
content of about 44% and a fat content of about 14%. The frozen par-fried 
potato strips are then enrobed with oil by spraying warm 
(.about.150.degree. F.) conditioned Primex 108 oil onto the surface of the 
frozen par-fries. About 5% fat is applied to the surface of the frozen 
par-fry by the spray enrobing process. The resulting oil-enrobed prebake 
fries comprise about 42% moisture and about 18% fat and are stored frozen 
at 0.degree. F. (-18.degree. C.) until oven finishing. 
The frozen oil-enrobed prebake fries are finished in a conventional home 
oven (General Electric). About 0.5 lb. of the prebake fries are placed 
onto a solid stainless steel baking tray in a single layer and baked for 
6-7 minutes at a temperature of 425.degree. F. (.about.218.degree. C.). 
The finished French fries have a crisp crust, a moist interior, and taste 
very similar to good deep-fat fried French fries. 
Example 4 
A reduced calorie fat composition is used to prepare enrobed prebake fries. 
The fat composition contains a nondigestible fat component and a 
"conventional" triglyceride component. The nondigestible fat component 
comprises a blend of a liquid and solid sucrose polyester (SPE) e.g., 
OLEAN.RTM., made by The Procter & Gamble Company. The nondigestible fat 
component is added to refined, bleached and deodorized soybean oil and the 
resulting blend is heated until all the solids are dissolved to provide a 
fat composition containing 75% SPE and 25% soybean oil. 
Russet Burbank potatoes at about 20% potato solids content are peeled, 
washed and cut into 1/4" wide.times.31/2" long potato strips to make 
shoestring style French fried potatoes. The potato strips are blanched in 
hot water (140.degree. F. 60.degree. C.) for about 5 minutes. The blanched 
potato strips are allowed to equilibrate at ambient conditions for 5 
minutes followed by partial drying in an oven. 
The partially dried potato strips are then fried in the above-mentioned fat 
composition for 90 seconds at about 375.degree. F. (.about.190.degree. C.) 
followed by freezing to make frozen par-fries. The frozen par-fries 
comprise about 55% moisture and about 11% fat. The frozen par-fried potato 
strips are then enrobed with the reduced calorie fat composition by 
immersing the frozen parfries in the fat composition having a temperature 
of about 335.degree. F. (.about.168.degree. C.) for about 1-3 seconds. The 
resulting prebake fries are again frozen. The frozen oil-enrobed prebake 
fries have about 12% oil coated on the surface; they comprise about 48% 
bulk moisture and about 22% total fat. 
About 128 grams of the frozen oil-enrobed prebake fries are placed on an 
open wire mesh tray in a single layer and then baked at a temperature of 
about 425.degree. F. (218.degree. C.) in a forced air convection oven 
(Wells Manufacturing Company, Verdi, W.Va., Model #M42003S) for about 3 
minutes. If desired, the French fries may then be subjected to a short 
(i.e. 5-30 sec.) blast of hot air or gas at high velocity to remove any 
excess surface fat and control greasiness of the finished fries. The 
resulting reduced calorie French fries have: a bulk moisture of about 40%; 
a total fat content of about 15%; an internal moisture content of about 
65%; a Surface Aw of about 0.4 and a French Fry Texture Value of about 
250. 
These oven-finished French fries are virtually indistinguishable from deep 
fat fried French fries.