Note: Descriptions are shown in the official language in which they were submitted.
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OIL ENROBED PAR-FRIED POTATO STRIPS
BACKGROUND OF THE INVENTION
The present invention relates to oil enrobed, and in particular frozen oil enrobed par-fried potato
strips which when oven fmished have a crisp surface layer and a moist inner core. The finished fry has
subst~nr~ y the same taste, quality and ~ha.a~ ia1i.,s as French fried potatoes that have been deep fried
in fat.
French fries are one of the most popular convenience foods. French fried pOtâtO strips,
cnrnmorly referred to as French fries, served in most fast food l~laulall1~ are ,.u~,Lased in bulk from
commercial suppliers in the form of partially fried (par-fried) and frozen potato strips which are stored in a
frozen con.li~ion until shortly before serving. At that point the par-fried potato strips are prepared for
con~ ~...ption by frying in fat or oil. In addition, frozen par-fried potato strips are also pu~llased by the
cOnaullll,. for pan frying, deep frying or oven fini~hing
The use of frozen par-fried potato strips instead of fresh potato strips has been widely adopted in
fast food ~ aulallla because of the convenience and savings in labor costs they provide. Frozen par-fried
potato strips also provide convenience for the C~JnSUIlll,.a who purchase them for home use. Few people
want to go through the plr;paudliun steps required to produce French fries from fresh potatoes.
Most l~laulallla, inrl--(ling the large franchise chains, prepare their French fried potatoes from
the frozen or chilled par-fried product, typically finishing them by deep-frying. Although par-fried potato
strips which can be oven finished are presently available, they suffer from a di~advau.Lgc in that when
they are baked, they produce limp, soggy fries which do not resemble deep fried potatoes in texture or
flavor.
The two most i~llpulkull textural attributes in French fried potatoes which have been deep fried
are interior moictn~ and crust clia~ulless~ The external surfaces of good textured French fries are
moderately crisp and are not excessively oily. The interior portions are also well cooked, tender, mealy
and free from soggi,.~ss.
Suppliers of frozen par-fried pohto strips have proposed a number of solutions to improve the
crispness of oven finished French fries. Most of the methods for producing "finished baked fries" require
coating the par-fried potato strip with firming agents such as modified shrches~ gums, ~lgin~tps calcium
salts, and the like. See for example U.S. 5,000,970 (Sh~ hh~g et al.) and U.S. 5,302,410 (Calder et al.).
Another method requires surface coating the par-fry with oil or fat, for example, U.S. 3,265,964 issued to
Kellermeier. The results obhined by such surface treatment plu~,elu~l, have had only a limited degree of
success.
The major problem with oven finished fries is that the texture of a high quality deep fried French
fry has never been duplicated. In particular, the same internal moist texture surrounded by a crisp yet
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tender outer surface or "crust" has not been achieved on a co~ .cid] scale. Although oil or fat coatings
have been applied to par-fries in the past, the oven-finished French fries produced tL~ o... are generally
limp and soggy or are dry and tough This may be due to any number of reasons; for example, the bulk
moisture and fat of the par-fry may not have been optimized for delivering a desirable texture upon oven
finiching, the desirable moist interior may have been lost in the course of the p~ uce;~aillg steps, or the crust
area may have become soggy due to the inability of water to escape during cooking.
It has been surprisingly discovered that oiVfat coated par-fries wherein the bulk moisture, interior
moisture and fat level are controlled, produce French fries having s~hct nti~lly optinli7.~d taste, color and
textural ch~,~ liali~ s when oven finished.
As has been stated, the production of oil coated French fries is known in the art. However, the
present invention offers signifir~ t improvements in the texture of the oven finished fry.
The present invention enables the ~,od)l.,lion of French fries in an oven which have deep fried
taste and textural properties. One aspect of the present invention is based in part on the al~niaillg
discovery that the prc-cllrubed par-fried potato strips must have a certain bulk moisture level. Another
aspect of the present invention is based on the fact that the par-fried potato strips are coated on the surface
with a specific levels of fat or oil.
Accordingly, it is an object of the present invention to provide par-fried potato strips, enrobed
with a surface coating of fat or oil, which when oven finished, closely resemble the texture and flavor of
deep fried fast food French fries.
It is another object of the present invention to provide a product which is prepared in an oven and
which provides a highly palatable French fried product, which has a crisp surface texture and a tender
moist interior.
It is still another object of the present invention to provide frozen par-fried potato strips which
can be finished in an oven of fast food 1~ or in the c~ 's home which is virtually
inrlictingllicha~le from deep fried French fried potatoes.
SUMMARY OF THE INVENTION
The present invention relates to oil enrobed par-fried potato strips suitable for oven finishing
CCIIII~JI iaill~,.
(a) par-fried potato strips having from about 34~/O to about 58% bulk moisture; and
(b) from about 8% to about 30% total fat;
said par-fried potato strips have a ~,lb,~ lly uniform surface coating of oil or fat wherein the surface
coating co...~. i5es from about 2% to about 15% by weight of said par-fried potato strips.
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The potato strips when oven finished have a color, texture, mouthfeel and taste which is virtually
h,di~ uishable from cuu~ ially prepared French fries that have been prepared by deep fat frying such
as MCDonaldsTM French fries.
DETAILED DESCRIPTION
The present invention relates to oil enrobed par-fried potato strips, and in particular, frozen oil
enrobed par-fried potato strips suitable for oven finishing prior to co~ tion Although the invention is
applicable to a number of finished heating IJluCe.~ S, it has particular application to toasters, toaster ovens,
forced air ovens, convection ovens, high air velocity ovens, hot air i...~- ~~ ~ ovens, infrared ovens,
combined convection/infrared ovens, combined microwave/convection ovens and conventional home
ovens. Potato strips of the present invention, when oven finished have the flavor and texture of deep fried
French fries.
As used herein the terrns "par-fry" or "par-fried" refer to potato strips that have been subjc~t~d to
at least one frying process (e.g. deep-frying) but which have not been CGIlllJI ' 'y cooked.
As used herein the tertn "oven finishing" refers to con~.li,.g the product to a ready-to-eat form
by cooking in a toaster, toaster oven, forced air oven, convection oven, high air velocity oven, hot air
hl~ .f~.l oven, infrared oven, combined convection/infrared oven, combined microwave/convection
oven or a conventional home oven.
As used herein the term "oven finished" refers to a product that has been subjected to an oven
baking process to convert it to a ready-to-eat form. Obviously, the advantages of the invention cannot be
realized until the oil enrobed par-fry is cooked, as by baking in an oven such as a forced air convection
oven, a combined infrared radiation/forced air convection oven or a conventional home oven. It is not
meant to imply that the final cooking step necessarily forms any part of the i..~ n, which is concerned
primarily with the ~111 it _ 9 of the par-fry.
As used herein the term "fat" or "edible oil" refers to edible fatty s ': ,e- in a general sense,
including natural or synthetic fats and oils co..~;~l;.,~ eccPnti~lly of triglycerides, such as, for example
soybean oil, corn oil, ~ -,nceed oil, sunflower oil, palm oil, coconut oil, canola oil, fish oil, lard snd
tallow, which may have been partially or e~ u, ': Iy hyd.og~,,.a~,d or modified ulh~wise~ as well as non-
toxic fatty materials having ~.op~ s similsr to triglycerides, herein referred to as fat substih~tes, which
materials may be partislly or fully intljgPctihle. The terms "fat" and "oil" are used hlt~.~hdngeably.
Reduced calorie fats snd edible non-digestil,~e fats, oils or fat sub~lit~r~ s are also included in the term.
As used herein the terrn "enrobed" refers to a ~ lly uniform coating on the surface of the
par-fry. The coating may also be flicc~ntinuouc (i.e. globules or droplets).
As used herein the term "conditioned oil" refers to oil which has been previously used for frying
for such a time that it has developed fried flavor.
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Unless otherwise stated, all p~ ,f 5, ratios or proportions e~p-~sed herein are by weight.
Pre-Enrobed Potato Strips
The pre-enrobed par-fried potato strips may be prepared according to the plucf saillg steps that are
conventional to most par-fry production tPrhniq-uPc The pre-emubed potato strips may either be prepared
from raw potatoes or from potato strips which have previously been par-fried or par-fried and frozen. Raw
potatoes of a variety known to be suitable for p..,~,~ui..g French fries (e.g., Russet Burbank variety), are
washed, peeled and trimmed in acco~dal)ce with conventional practice and are cut into strips of a desired
size and shape ~ua~uul~ily used for French fries such as shoestring potato strips, crinkle-cut strips, and
straight cut thick strips. After cutting, the strips may be washed to remove surface starch.
In the practice of the present invention it is preferred that the potato strips known in the art as
"shoestrings" be used. Shoestring potato strips, as used herein refer to potato strips that are from about
3116 to about 5/16 inch square in cross-section and from about 2.5 inches to about 5 inches in length.
Other potato strips which may be used herein are known in the art as "crinkle cut" strips. Such
strips usually average from about 5/16 to about 1/2 inch in cross-section and from about 2 to about 4
inches in length.
Also, straight-cut thick potato strips (also called regular-cut~ of from about 5/16 to about 1/2 inch
square in cross-section and about 2.5 to about 5 inches in length may be used. Larger potato strips of the
type referred to as "steak fries" may also be used. Typically, these potato strips have a rectangular cross-
section of about 1/2 inch by about 7/8 inch.
The potato strips are blanched according to conventional procedures known in the art. This is
done to inactivate enzymes and remove excess free sugars from the surfaces of the cut strips. Typically the
strips are blanched by i Illlle~aion in hot water at a te~ alul~ of about 140~F (60~C) to about 200~F
(93.3~C) for about 3 to about 20 minutes depending upon strip size. Alternatively, the strips may be
blanched in steam, at ~m-o~ ic pressure for about 2 to about 10 minutes.
Following the b' ' ing step, the potato strips may be treated according to conve, ~; -' methods
known in the art. For instance, the potato strips may be subjected to ~ water u~ iou steps to
further leach excess sugars or the strips may be treated with sodium acid pyl~rh~ ~ ~ (SAPP), a
chel~ing agent used to prevent discoloration of the strips. Dextrose (corn sugar) may also be applied to
the surface of the strips in order to yield a desired level of brown color devclu~ during subs~
plUC~ Other ll~dt~ .lL~ known in the art may also be used.
After blanching and the optional treatments des~,;l,ed 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
ucclul~s used in the ~JIu ' : on of par-fried potato strips may be used, such as, for example, subjecting
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the potato strips to heated air at t....p~ lres of from about 150~F (6S.6~C) to about 350~F (176.7~C) for
from about 5 to about 20 minutes. Microwave or radio-fi~qln,..cy drying may also be used.
The blanched potato strips are then u..~l.L.~ed in an edible oil for a time s--rl~ "t to produce par-
fried potato strips having from about 38% to about 58% bulk moisture. Typically, the shoestring-cut
potato strips have from about 40% to about 56% bulk moisture. Preferably the potato strips have from
about 42% to about 54%, more preferably from about 44% to about 50% moisture. These par-fried potato
strips have from about 6% to about 25%, ,..l~r~,.ably from about 8% to about 22%, more preferably from
about 10% to about 20% and most preferably from about 12% to about 18% total fat. This can be
achieved by immersing the potato strips in oil, for example, at a temperature of from about 270~F (132~C)
to about 385~F (196~C). Of course the immersion time will be d~p~n~ent on the specific oil le.ll~.aLul~,
~limen~onc 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 ter~nirlu~s such as a
heated oil spray which 5UIIUUIIdS the potato strip with hot oil or frying using an oil foam can also be used.
Thicker-cut potato strips (e.g., straight, regular-cut, crinkle-cuts and steak fries) maybe fried to
slightly higher bulk moisture contents. For example, regular and crinkle-cut par-fries (5/16" to 1/2" cross
section) may be fried to about 40% to about 60% bulk moisture content; and steak fry par-fries (1/2" by
7t8" cross-section) may be fried to about 42% to about 62% moisture.
In a preferred embodiment of the present invention the potato strips which are to be enrobed have
been previously par-fried and frozen. The pre-c..lubed par-fried strips are commercially prepared and may
have been subjected to multiple p.-)ces~.ng steps (i.e., par-fry and freezing, multiple par-fryings and
freezing). The only limit.~'ionc are that the pre-e,,rûbed par-fried potato strips meet the requisite bulk
moisture and fat level.
After par-frying the par-fried potato strips may be immerli~ly enrobed with oil, or they may be
cooled or frozen prior to enrobing. Chilling or freezing of the par-fries may be accu...pli ,hed by methods
known in the art. For example, the par-fried potato strips may be sul,;~,t~d to a blast of cold air at a
t~,..pelalu.e of less than about -20~F, or the strips may be hl.~..cl~ed in a liquid IcrriE,_.a ll, such as liquid
nitrogen. Conventional freezing PlUCe.S3eS can be used. It is preferred that the par-fried potato strips be
frozen quickly, i.e., in less than 20 minutes, preferably less than 5 minutes after completion of the par-
frying.
Surface Coatin~/Enrobin~
In order to ensure that an outer crust similar to that of a deep fried French fry will be produced in
an oven, it is necessary to coat the surface of the par-fried potato strips with an edible fat. The surface
coating may be applied ;""..r.l; ,t~ly after removal of the par-fried potatoes from the fryer or the coating
can be applied to frozen, chilled, or room t~,...p~,, alul~ par-fried potato strips.
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The fat compositions used to coat or enrobe the par-fried potato strips can be applied to the
surface of the potato strips by a variety of means inrhlfling immersion, dipping, spraying, blowing,
pouring, pan coating (e.g., in a revolving pan), tumble coating, rolling around in a container of a fat
comrosition, falling film methods, enrobing and curtain coating. Preferably the edible liquefied fat is
applied in a ~ ly 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
.I;cc,...li...~ous so long as it is uniformly ~liall ~utell
To achieve oil levels on the surface of the potato strips, in the range of from about 2% to about
15% by weight of the par-fried potato strips, the following oil spray techni~lue can be used. The oil is
m~int~in~-d at a ~e.ll~;..alul~ of from about 70~F (21~C) to about 200~F (93~C), preferably from about
100~F (37.8~C) to about 180~F (82.2~C) and more plefe~ably from about 120~F (48.9~C) to about 160~F
(71.1~C). The spray nozzles are arranged to ~lminict~r the oil evenly whether the oil is atomized during
the spraying or simply sprayed in fine droplets, pl~f~lably over the potato strips in a single layer. The rate
of application of the oil, determined by the volume of oil that is sprayed and the amount of par-fried potato
strips that are sprayed, is ~,.efe.ably such that the weight of the par-fried potato strips is inc, eâ3ed by about
2% to about 15% after spraying.
A surface oil coating can also be applied via an i :,iu.. or dipping te~hniq~ For example,
the par-fried potato strips are frozen and equilibrated at 0CF (-17.8~C). The frozen par-fried strips are
immersed rapidly (e.g. 1-3 seconds) into oil at a t~ alul~ of about 335~F (168.3~C) and then
i,-,---c~ ly re-frozen by jJ~ C~jUn in liquid nitrogen. This type of enrobing process adds a coating of
oil onto the surface of the par-fried potato strips s ~ rri~ ;l .,1 to increase the weight of the strips by about 2%
toabout 15%.
It is hllp~JIIa ll to maintain the fat in a s~l~ st~nti~lly 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.
Edible Oils
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 beef tallow, lard, cottonseed oil,
canola, soybean oil, corn oil, palm oil, fish oil, safflower oil, ~ullllu..~n oil, coconut oil, peanut oil,
medium chain triglycerides, ~L,u~lul~d triglycerides contlining a combination of short or medium chain
fatty acids and long chain fatty acids (e.g. Caprenin-like) and the like or culllbillalions thereof. If desired
the oils may be con~liti.)ned or flavored, see Flavored Ve~etable Oils as a Substitute for Beef Tallow in
Deep Frvin~ Applications, Food Technology, pp 9û-94 (1989) and U.S. Patent 5,104,678 (Yang et al.)
~ referably the edible fat or oil used to fry and enrobe the par-fried potato strips has a free fatty
acid level of about 0.8% or less.
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The edible oils used for frying or enrobing the par-fried potato strips include natural or synthetic
fats and oils. The oils may be partially or completa!y hydrogenated or modified otherwise. Additionally
non-toxic, fatty materials having ~"o~.lies similar to triglycerides such as sucrose polyesters and Olean M,
from the Procter and Gamble Company, and reduced calorie fats, polyol fatty acid polyesters, and
diversely c;.~e.iried polyol polyesters or combinations of regular fats and fat suhstitutPc may also be used
herein.
One reduced calorie fat that has been found to be useful cv~u~iaes a fairly high level (e.g., at
least about 85%) of combined MML and MLM trigiycerides, where M is typically a mixture of C8-CIo
saturated fatty acids and L is predom ~~ lly behenic acid, but can be C20-C~4. See U.S. Patent 4,888,196
to Ehrman et al., issued December 9, 1989 and U.S. Patent 5,288,512 issued to Seiden, February 22, 1994
for the synthesis and more detailed de;.", i~lio" of these reduced calorie fats.The MML, LLM, triglycerides are further chala.,t~,. i,~d by having a fatty acid csn.l-sC;~ion which
culll~fiacs from about 35% to about 60% combined C8-CIo saturated fatty acids, a ratio of C8-CIo
saturated fatty acids of from about 1:5 to about 25:1, and from about 35% to about 60% behenic fatty acid.
By "reduced calorie " as used herein is meant fats that provide an at least about 10%, and
preferably an at least about 30%, reduction in calories relative to corn oil. The reduction in calories
provided by these reduced calorie fats can be determined by studies similar to that described by Peters,
J.C. et al., Journal of the American Colle~e of Toxicolo~v. Vol. 10, No. 3, 1991, pp. 357-367.
By "polyol" is meant a polyhydric alcohol contqining at least 4, preferably from 4 to 11 hydroxyl
groups. Polyols include sugars (i.e., l.-onss~rel-- idcs, diaaccllalides, and tfiaaccllAIides), sugar alcohols,
other sugar derivatives (i.e., alkyl gl~co5ide5), polyglycerols such as diglycerol and triglycerol,
pentaerythritol and polyvinyl alcohols. Specific examples of suitable sugars, sugar alcohols and sugar
derivatives include xylose, a,al.2.ose, ribose, xylitol, erythritol, glucose, methyl ghlcoside m~nnssP,
~alq~tose 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 crmt~ining 4 or more fatty acid ester groups are sulJa~ ially non-
digestible and cc.n~e~ ly non-absu,l,abl by the human body. It is not necessary that alt of the hydroxyl
groups of the polyol be esterified, but it is ~lel~. ble that ~ ~chqAride mole IPS contain no more than 3
ified hydroxyl groups for the purpose of being non-digestible. Typically, sllllalA-~t;~lly 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
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synthetic fatty acids. The fatty acid radicals can be saturated or unsdlul ' ~, in~hl~ling positional or
geometric isomers, e.g., cis- or trans- isomers, and can be the same for all esoer groups, or can be mixtures
of different fatty acids.
Liquid non-digestible oils have a complete melting point below about 37~C include liquid polyol
fatty acid polyesters (see Jan~ ; U.S. Patent 4,005,195; Issued January 25, 1977); liquid esters of
tricarballylic acids (see Hamm; U.S. Patent 4,508,746; Issued April 2, 1985); liquid diesters of
dicarboxylic acids such as derivatives of malonic and succinic acid (see Fulcher; U.S. Patent 4,582,927;
Issued April 15, 1986); liquid triglycerides of alpha-branched chain carboxylic acids (see Whyte; U.S.
Patent 3,579,548; Issued May 18, 1971); liquid ethers and ether esters cont~ining the neopentyl moiety
(see Minich; U.S. Patent 2,962,419; Issued Nov. 29, 1960); liquid fatty polyethers of polyglycerol (See
Hunter et al; U.S. Patent 3,932,532; Issued Jan. 13, 1976); liquid alkyl glycoside fatty acid polyesters (see
Meyer et ai; U.S. Patent 4,840,815; Issued June 20, 1989); liquid polyesters of two ether linked
hydroxypolycarboxylic acids (e.g., citric or isocitric acid) (see Huhn et al; U.S. Patent 4,888,195; lssued
December 19, 1988); liquid esters of epoxide-extended polyols (see White et al; U.S. Patent 4,861,613;
Issued August 29, 1989); all of which are i..co~ ~,u~ ~ d herein by reference, as well as liquid polydimethyl
siloxanes (e.g., Fluid Silicones available from Dow Coming).
The polyol fatty acid polyesters that are liquid have minimal or no solids at a t~.ll,.J~.dlul~; of 98.6
~F (37~C), i.e., body t~ ,dlul.,s. These liquid polyol polyesters typically contain fatty acid ester groups
having a high proporilon of C12 or lower fatty acid groups or else a high p~Jullion of C18 or higher
ullsdlulal~d fatty acid groups. In the case of those liquid poiyol polyesters having high IJlU~JUlliolls of
ullaalulal~d C18 or higher fatty acid groups, at least about half of the fatty acids incu.~ulaled into the
polyester molecule are typically ull~,alulat~,d.
The liquid polyol fatty acid polyesters can be prepared by a variety of methods known to those
skilled in the art. These methods include: lla.ls~,.,t~,.irlcation of the polyol (i.e. sugar or sugar alcohol)
with methyl, ethyl or glycerol fatty acid esters using a variety of catalysts; acylation of the polyol with a
fatty acid chloride; acylation of the polyol with a fatty acid anhydride; and acylation of the polyol with a
fatty acid, per se. See, for . '~, U.S. Patent Nos. 2,831,854, 3,600,186, 3,963,699, 4,517,360 and
4,518,772, all of which are i'llcu.~,o.al~d by .~f~.~nce, which disclose suitable methods for preparing
polyol fatty acid polyesters. Specific, but non -limiting, e~..pl~s of the preparation of liquid polyol
polyesters suitable for use in the practice of the present invention are disclosed in Young et al; World
Patent Application US91-02394 (publication number WO91-15964); published October 31, 1991, which is
hlcul~Jolaled by reference. The liquid polyol polyesters can contain behenic acid.
Polyol fatty acid polyesters that are solid at te~ alul~s of about 37~C and higher have the
ability to bind high levels of edible liquid non-digestible oils, such as liquid polyol polyesters previously
described, when included in a~J~lu~liale arnounts. This capacity to bind liquid non-digestible oils enables
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g
these solid polyol polyesters to control or prevent the passive oil loss problem a~coci~Pd with the
ingestion of such liquid oils.
Diversely Esterified Polyol P~ .Jt~. a
- One preferred class of suitable solid polyol polyesters for use in the liquid/solid blend are those
wherein the esters groups comprise a combination of (a) C12 or higher u~aLu.dled fatty acid radicals, C4-
C12 fatty acid radicals or mixtures thereof, and (b) at least about 15% C20 or higher saturated fatty acid
radicals, preferably at least about 30%, more preferably at least about 50%, most preferably at least about
80%, long chain saturated fatty acid radicals.
Suitable u~aaLu~àled fatty acid radicals contain at least 12, plefe,àbly from 12 to 26, more
preferably from 18 to Z, most preferably 18, carbon atoms. Suitable short chain saturated fatty acid
radicals contain from 4 to 12, preferably from 6 to 12, and most preferably from 8 to 12, carbon atoms.
Suitable long chain saturated fatty acid radicals contain at least 20, preferably from 20 to 26, most
preferably 22, carbon atoms. The long chain UlladlUI_ d fatty acid radicals can be used singly or in
mixtures with each other, in all proportions, as is also the case with the short chai n and long chain
saturated fatty acid radicals. In addition, straight chain (i.e. normal) fatty acid radicals are typical for the
short chain and long chain saturated fatty acid radicals, as well as the long chain unsaturated fatty acid
radicals. Examples of suitable long chain ul.adlu.d~ed fatty acid radicals for use in these solid polyol
polyesters are monou~saLltl t~,d radicals such as lauroleate, myristoleate, palmitoleate, oleate, elaidate, and
erucate, and polyunaaluldl~d radicals such as linoleate, ar~hid linoleate, eico~.l.- ,u. .~o~r and
docos~ ..u~lr In terms of oxidative stability, the m-~nou..~l...aled and diullsdlu-dt~d fatty acid
radicals are preferred. Examples of suitable short chain saturated fatty acid radicals are acetate, butyrate,
h~ .O~lt, (caproate), oct~n- (caprylate), dc~ --.oa'~ (caprate), and dodc~a~.oale (laurate). Examples of
suitable long chain saturated fatty acid radicals are e.c: o~te (arachidate), d~cos -~ (behenate),
tetraccs~- (lignocerate), and hPY:~os -oate (cerotate).
Mixed fatty acid radicals from oils which contain s ~ .ti~l amounts of the desired long chain
unsaturated fatty acids, short chain saturated fatty acids, or long chaln saturated fatty acids can be used as
sources of fatty acid radicals in ~ ,palhlg the solid polyol polyesters useful in the liquid/solid blend type of
non-digestible fat coll,pul~ ll. The mixed fatty acids from such oils should preferably contain at least
about 30% (more preferably at least about 50%, most preferably at least about 80%) of the desired long
chain Ullaa~ , short chain saturated or long chain saturated fatty acids. For example, palm kernel oil
fatty acids can be used instead of a mixture of the respective pure saturated fatty acids having from 8 to 12
carbon atoms. Similarly, rapeseed oil fatty acids or soybean oil fatty acids can be used instead of a
mixture of the respective pure monou~ n~at~d and pOlyullaalula~ed fatty acids having 12 to 26 carbon
atoms, and hardened (i.e., hydlu~e~lated) high erucic rapeseed oil fatty acids can be used in place of a
mixture of the respective pure long chain saturated fatty acids having from 20 to 26 carbon atoms.
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P~ef~lably, the C20 or higher saturated fatty acids (or their derivatives, e.g. methyl esters) are
concentrated, for example, by riictill~tion An example of source oils for these solid polyol polyesters are
high oleic sunflower oil and s-ll,a~ lly completely hydrogenated high erucic rapeseed oil. When
sucrose is 5nbs~nti~lly completely esterified with a 1:3 by weight blend of the methyl esters of these two
oils, the resulting polyester has a molar ratio of u.l~alulal~d Clg acid radicals to saturated C20 or higher
acid radicâls of about 1:1, the saturated C20 and C22 acid radicals being about 28.6% of the total fatty acid
radicals. The higher the proportion of the desired long chain ullaalulal~;d/short chain saturated and long
chain saturated fatty acids in the source oils used in making the solid polyol polyesters, the more efficient
the polyesters will be in their ability to bind the liquid non-digestible oils.
The molar ratio of (a) long chain ul.sdlu~al~,d fatty acid radicals or short chain fatty acid radicals
or mixtures thereof, to (b) long chain saturated fatty acid radicals, is from about 1:15 to about 1:1.
Preferably, this molar ratio of (a) to (b) radicals is from about 1:7 to about 4:4, most preferably from about
1:7 to about 3:5.
Examples of solid polyol fatty acid polyesters ~ g mixtures of (a) and (b) radicals include
sucrose t~lml~eh~ tt:llacalJIylate, sucrose p. .II;.h~ h. .~lr trilaurate, sucrose h~ ~hch~ dicaprylate,
sucrose h~,~dlJ~hendle dilaurate, the sorbitol h~x~esttor of palmitoleic and arachidic fatty acid radicals in a
1:2 molar ratio, the raffinose octaester of iinoleic and behenic fatty acid radicals in a 1:3 molar ratio, the
maltose hept~cstP- of a mixture of sunflower oil and lignoceric fatty acid radicals in a 3:4 molar ratio, the
sucrose octaester of oleic and behenic fatty acid radicals in a 2:6 molar ratio, the sucrose octaester of
lauric, linoleic and behenic fatty acid radicals in a 1:3:4 molar ratio, and the sucrose hepta- and o - a
of C 18 mono- and/or di-ullaatul_ ~ fatty acid radicals and behenic fatty acid radicals in a molar ratio of
u.lsdlulat~d:behenic acid radicals of about 1:7 to 3:5.
Enrobin~ parameters
The edible oil is applied to the surface of the par-fried potato strips in an amount sufficient to
prevent rapid migration of moisture from the interior during oven finiching Typically an amount of from
about 2% to about 15% by weight of the par-fried potato strips, preferably from about 3% to about 12%,
and more~~,lef~,.dbly an amount of from about 4% to about 10% oil is used to coat the surface of the par-
fried potato strips.
The oil enrobed par-fried potato strips before baking (shoestring-cut), typically cGIl~ ise from
about 34% to about 54% bulk moisture. P~t:fe.al,ly, the aho~ iulg cut, oil enrobed par-fried potato strips
colllpliae from about 36% to about 52%, more preferably from about 38% to about 50%, and even more
preferably from about 40% to about 48% bulk moisture. Ad~lition~lly, the oil enrobed par-fries before
baking culll~lise from about 8% to about 30% total fat, wherein the level of surface fat is from about 2%
to about 15% by weight of the par-fried potato strips. Preferably, the oil enrobed par-fries before baking
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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% total fat.
Thicker-cut oil enrobed par-fried potato strips may have slightly higher bulk moisture contents.
For example, regular and crinkle-cut oil enrobed par-fries (5/16" to 1/2" cross-section) may comprise
about 36% to about 56% bulk moisture; and steak fry oil enrobed par-fries (1/2" by 7/8" cross section)
may comprise about 38% to about 58% bulk moisture.
After coating the surface of the par-fries, the oil enrobed par-fried potato strips may be frozen,
packaged and stored or shipped for Snb!;e~l~lf ~1 use. Typical frozen storage t~ ,.alul~ ranges from
about -20~F (-28.9~C) to about 10~F (-12.2~C). Freezing the oil enrobed par-fried potato strips may be
accomplished by methods known in the art. The strips may be c~.r t~eted with a liquid t~rr;g~ l which is
at a t~.llp~.ature below 0~F (-17.8~C), preferably below -20~F (-28.9~C). One may also use any of the
fluo.v.,a.bons which exist in the liquid state. P~li~ ulally ~,~f~....,d is the use of liquid nitrogen.
The step of cnntactinp the l~;rr;g~.a~ll with the oil enrobed par-fried potato strips may be
accomplished by dipping the strips in a pool of the r~Gig~ ll, or by spraying the l~L;ge~alll on them. In
any case, the time of contact is limited so that preferably only the surface layers of the strips become
frozen. The time required to achieve the desired degree of freezing will vary depen~ling on such factors as
the te.ll~.alul~ of the r~;Gi6~.ant, the size of the potato strips, etc. The freezing may either be a surface
freeze or a total freeze. It is not essential that the surface freeze be accomplished by the use of a liquid
l~Gi6~lal~t; one may use a r~:r~ig~,.a~l in a gaseous state. For example, the oil enrobed par-fried potato
strips may be aubje~tcd to a current of cold air at a te,..p~.alule below 0~F (-17.8~C). A convenient
method is to use a conventional blast freezer or a high velocity current of air where the potato strips are
subjected to a blast of cold air at a t~ c-alul~: of less than or equal to about -20~F (-28.9~C).
Alternatively, the potato strips may be placed in a freezer colllp~l~ ,nl, for example, at -10~F (-23.3~C),
of a suitable size such as a coln---c.-;idl or industrial unit.
However, the freezing step may be excluded and the enrobed par-fry potato strips may be
imm~ ' ~ Iy oven finished without freezing.
O~en Finishin~
The time period and t~ p~.atul~ for pr. ~alillg the oven finished French fries will vary depf n~ g
upon the quantity of strips, their initial l~lllpe.dtUI~:, the type of oven and the oven conditions (e.g.,
t~ alul~ air velocity) used, and the thermal l.,u~,,li.,s of the oil-enrobed par fries. Of particular
i n~o,la..ce 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 par fry. In
general, higher thermal conductivities and higher surface heat transfer coefficients will result in more rapid
transfer of heat from the oven to 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
,
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properties are of particular impo.i _a, The desirable thermal conductivities at oven t~llp~,,alulc of the
low moisture crust region in the oil-enrobed par fry are from about 0.1 to about 0.3 watts/m-~C. The
desirable thermal conductivities at oven l~ p~.alùre of the high moisture core region in the oil-enrobed
par fry are from about 0.4 to about 0.~ watts/m-~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 coc~ l of the oil e. obcd par fry is a function of forced air velocity,
air l~.np~. c, and the nature of the oil film at the surface of the par 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 coPffirientc at oven ~ lp~alulc of the oil e,..~,bcd par fry in the oven are from about 50 to about
400 watts/m2 ~C. The surfacc heat transfer coefficient is increased as a concequPnce of enrobing the par
fry with an edible fat or oil, which ulCIcaSeS the con~ rti~r of heat from the surrounding air to the fry
surface. The surface of the 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. Inc.~ing the velocity of the oven air at the surface of the par fry will also increase the
surface heat transfer coccrrlc;.,.lt. The oven air velocity should be high enough to achieve a ~ r~. ~o,y
heat transfer coeffi~ient, but not so high as to strip away the enrobing oil on the surface.
The oven finished French fries are a golden brown color and have a crisp crust and a moist
interior. The finished French fries have a color, texture, mouthfeel and taste which closely l~s~albles
co...l.,cl~;ally prepared French fried potatoes that have been prepared by deep fat frying, such as
MCDonaldsrM.
Ad ' - -I Ic~r~ients
Flavoring agents, such as salt, pepper, butter, onion, or garlic may be added to the oil to enhance
the flavor or modify the flavor to any desired taste. One skilled in the art will readily a~ ,ciale that the
ar~ ;onrd listing of na~u.ll.g 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.
(I)ther hlgll,.ii~.l~ known in the art may also be added to the edible fats and oils used to fry and
enrobe the par-fried potato strips, i~ch~ n~ tc such as TBHQ, che!~ tinp agents such as citric
acid, and antifoaming agents such as dimethylpolysiloxane.
A primary advantage of the present invention is that it provides par-fried potato strips which,
upon oven finiching. yield French fries of excellent texture and taste.
Another advantage of the h~ n is that the French fry potato producer is now able to produce
oven-finished French fries having excellent texture. Often, in CollllllC,.L,ial operations the par-fried potato
strips are deep-fried to obtain a desirable texture. As a result of this invention, the final frying step is
completely l'lm~f S~'; because the crisp crust and moist interior of the oven finished fries are virtually
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jn~ic~ingnichahle from French fries which have been finished using a deep frying process. Besides being
advant~geouc from a texture standpoint, the invention also offers an economir~l advantage to the
producer. It should be I ~ d that the amount spent for cooking oil is one of the major eYr~ "~
incurred by the producer of French fries .
While specific pl~f.,.~;d processing steps have been disclosed to facilitate an und~,aL~ding of the
invention, the fun~tion~l equivalents can be s ~ba~ lf d or ad~l;l;o~ d ~ a may be added without
departing from the spirit or essential chala.,t~.;alics of the present invention.
ANALYT/CAL PROCEDURES
The methods for determining the bulk moisture and total fat of par-fried potato strips and oil
enrobed par-fried potato strips are set forth below:
Determination of Bulk MGLIUr~: Content
Moisture content is determined by a forced air oven method as follows:
1. Uniformly grind up a ;p~es~,.lali~e sample of potato strips in a blender or conventional
food plùcessol~
2. Accurately weigh ap~lu~ilnd~ly S grams of ground sample (weight "A") into a
previously tarred metal pan or dish.
3. Place the metal dish c- nt~ining the sample in a forced air convection oven at 105~C for 2
hours.
4. After 2 hours, remove the metal dish cont~ining the dried sample and allow to cool to
room t~ u- e in a ~ c~ ., over a d~ ~ir~. ll such as anhydrous calcium sulfate.
5. Re-weigh the dish cont~ining the dried sample and calculate the weight ûf the dried
sample (weight "B") by aubtla~ g the dish tare weight.
6. C~iru' ~ the percent moisture of the sample as follows:
% Moisture = [(A - B) / (A)] x 100
Det~ n of Total Fat Content
Total fat content is determined by a solvent e,~ clio.. method as follows:
Apparatus
1. Soxtec HT6 extraction system; unit includes heating block and cooling condenser.
2. Recirculating water bath for cooling con~
3. Recirculating oil bath for heating block.
4. Extraction beakers.
5. Extraction thimbles, 26 mm (Fisher TC 1522-0018)
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6. Nitrogen purging gas
7. Vacuum drying oven
8. Analytical balance (4 place)
9. Di~ i.,g 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 ~ ;u~live sample of pohto strips in a blender or conventional food
plucessol .
2. Accurately weigh (to four places) a piece of glass wool (s~ t in size to contain sample
pieces in the thimble) and the eAl,a,t; thimble; record weight of thimble + glass wool (weight
~A~
3. Load the ground sarnple 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").
5. Place two or more boiling stones into an e.~lla~lion beaker and weigh (to four places); record
weight of extraction beaker + boiling stones (weight "C").
6. Place loaded thimbles on the w~lra~,liOIl 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~C and water cooling bath to 28.3~C and allow l~ alu~ to
e~uilibl
9. Lower the loaded thimbles into the extraction beaker c.,,,~ g the solvent and allow to boil in
the solvent for 60 minutes with the cond~nc~r's pet cock in the open position.
10. Raise the thimbles to the rinsing position and rinse for 60 minutes.
I l. Turn the con~l~ncerls 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~C, for 30 minutes at full vacuum.
13. Allow the beaker to cool to room lulllp~,lalulc; and weigh (to four places); record the weight of the
beaker + boiling stones + extracted fat (weight "D").
14. Calculate percent total fat as follows:
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% Fat = [(D - C) / (B - A)] x 100
Accordingly, the ~liccl<s~d embodi~ ,.,la are con~id~.ed in all respects to be illustrative and not
restrictive. The scope of the invention is in-' I by the appended claims.
F.~s- p~ I
Frozen cv~ln.,~,idl shoestring cut par-fried potato strips are an ~cceptnbie starting product (e.g.,
Simplot Par-Fries, J. R. Simplot Co., Caldwell, ID). A typical l)locesaillg history may include: sorted and
graded Russet Burbank potatoes are peeled, washed, trimmed and cut axial1y into sLoe~l, illg strips (0.25
inch by 0.25 inch). The potato strips are blanched in hot water at 150~F to about 178~F (65.5~C to about
81.1~C). for 15-20 minutes and oven dried at 150~F to about 158~F (65.5~C to about 70~C) for 6-7
minutes. The partially dried strips are then par-fried in v~g~,lable oil at 375~F to about 385~F (190.5~C to
about 196.1 ~C) for 30 to 60 seconds. The par-fried potatoes are cooled and frozen at -30~F (-34.4~C), and
par~a~Pfl The par-fried potato strips have a moisture content of about 64%.
About I Ib. of the pae~ d frozen par-fried potato strips are further p~oc~ ,d by frying in a 45
Ib. oil capacity fryer cont~ining Primex 108 ve~, tAb'~ oil ( blend of partially hy~L.g ~ soybean oil and
corn oil; available from The Procter & Gamble Co.) for about 3 minutes at a t~,..lp~ u,c of about 290~F
(143.3~C). The resulting par-fries are ;.. c l; ~ly 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%.
ImmP~i Iy after being frozen the par-fries are enrobed with oil by hll~lclaing in liquid oil (con~lition~d
Primex 108) having a t-,.llp~.atul~ of about 335~F (168.3~C) for about 1-3 seconds. The resulting oil
enrobed par-fried potato strips are again frozen by i...lll~,.aion in liquid nitrogen. The frozen potato strips
are packed into tightly sealed, i.e. airtight, packages and stored at normal freezer temperatures of
approxim~ Iy 0~F (-17.8~C) to about -20~F (-28.9~C). The oil enrobed par-fried potato strips contain
about 10% surface fat by weight of the potato strips. The total fat level is about 22% and the bulk
moisture level is about 43%.
F. -~nD!~ 2
Erozen ' - illg-CUt par-fried potato strips available to fast food l~ aul~ulb are obtained for
~drlitio~ luceiaing (e.g., Payette Farrns Shûe~tring Frozen Potatoes, J. R. Simplot Co., Caldwell, ID). It
is understood that such conventional frozen potato strips are derived from whole potatoes which have been
peeled, cut, water or steam bl~nrh~l and possibly dried partially with hot air. The potato strips are
thereafter par-fried in veg~,~able oil for a~Jpl~J~illlately 30-60 seconds at about 375~F (190.5~C) and frozen.
The resulting par-fries have a bulk moisture content of about 70%.
The above~ ;on~d par-fried potato strips are further processed: First, the frozen potato strips
- are fried a second time by immersing in Primex 108 ve~ ablc oil (available from The Procter & Gamble
Co.) for 3 minutes at a t.,-..p~,.dlUI~ of 335~F (168.3~C). The par-fried potato strips are then frozen in
.
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liquid nitrogen for 20 seconds and stored at -20~F(-28.9~C). The resulting frozen par-fried potato strips
have a moisture content of about 44% and a fat content of about 15%. The frozen par-fried potato strips
are enrobed with oil by hlllll~. g in liquid veg.,tab'e oil (confliti-ned Prirnex 108) having a t~ alulc
of about 335~F(168.3~C) for about 1-3 seconds. The oil enrobed par-fries are then frozen by i ~,ion
in liquid nitrogen for about 20 seconds. About 10% fat is applied to the surface of the frozen par-fry by
this enrobing process. The oil c.~vbed par-fried potato strips comprise about 40% bulk moisture and
about 23% total fat. The oil enrobed par-fried potato strips are finish baked in a forced air convection
oven (Wells ~ ,..ur~ 1,.. i..g Co., Verdi, NV, model #M42003S) at a Ic...p~.alu~e of about 400~F(204.4~C)
for about 2.25 minutes. The resulting fries are virtually identical to fries which are prepared by deep
frying.
'~.Y~ C1~3
A reduced calorie fat cv~ n- :~ion is used to prepare the prc-e"robed par-fried potato strips in the
following example. The fat co~ o,;lion contains a non-~ ,c~liblc fat co ~ t and a "conventional"
triglyceride cu~ on n The non-di~ ;LI~ fat co...l.ù~ cG."~,.i.,es a blend of a liquid and solid sucrose
polyester (SPE). The non-digestible fat cv".,., - 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 cumrG~;lion
cont~ining 75% SPE and 25% soybean oil.
Russet Burbank potatoes at about 20% potato solids content are peeled, washed and cut into 1/4
inch wide by 3 1/2 inch long potato strips to make ~,hoe;,ll",g style French fried potatoes. The potato strips
are blanched in hot water (140~F;60~C) for about 5 minutes. The blanched potato strips are allowed to
equilibrate at ambient co-~-lil iOIlc for 5 minutes followed by partial drying in an oven.
The partially dried potato strips are then par-fried in the above-mentioned reduced calorie fat
co,..po~;~ion for 90 seconds at 375~F(190.5~C), followed by rapid freezing to make frozen par-fries. The
frozen par-fries cu.,-p.k,e about 55% moisture and about 11% fat. The frozen par-fried potato strips are
then enrobed with the reduced calorie fat cu...po~;~ion by i".-..~.~,i-,g the par-fried in the fat cu...; o,;';on
having a t~."l,~,.at~ue of about 335~F(168.3~C) for about 1-3 seconds. The oil enrobed par-fried potato
strips are again frozen. The frozen par-fries have about 12% oil coated onto the surface. The oil en,ubed
par-fried potato strips comprise about 48% bulk moisture and about 22% total fat. The oil enrobed par-
fries are packed into tightly sealed, i.e. airtight, p ~ a~es and stored at freezer t~.ul~ u~c;, of about 0~F.
