Formulation of dough-based fried snack foods

The addition of a small amount of a lecithin-in-water suspension to the formulation of dough-based fried snack foods improves dough transfer, sheeting and cutting, and significantly reduces clumping during frying, without the rapid buildup of free fatty acids, and without significant darkening of frying oil normally associated with the frying of foods containing lecithin.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an improvement in the formulation of dough-based 
fried snack foods, especially products made from potato flakes. 
2. Background Art 
Food preservation is a long practiced art, made necessary by the seasonal 
nature of most cultivated crops, the action of cellular enzymes, the 
ubiquity of mycobacteria, insects and rodents, and by the economic 
advantage obtained by shipping foodstuffs from fertile growing areas to 
locations of greatest demand. The preparation of peserved foods frequently 
entails certain steps necessary to return the food to its normal 
appearance and taste. For centuries, potatoes have been a staple in the 
diet of Europeans and Americans. Whole potatoes were stored in cool 
buildings and cellars, and cooked by boiling or baking. Chemical changes 
in the potato, specifically the conversion of starch to reducing sugars 
and the "greening" due to the formation of chloroplasts, had little effect 
on the nutritive value or final appearance of the meal. Fried potato 
foods, such as french fries, shoestring potatoes, and especially potatoe 
chips, however, are discolored when reducing sugars are present. In the 
case of potato chips, only certain varieties of potato can be used to make 
a commercially acceptable chip, and numerous processes have been developed 
to store and prepare potatoes for slicing. 
In recent years, much of the potato crop in the Western United States has 
been converted to potato flakes or flour. The removal of the water (as 
much as 80% of the weight of some varieties) makes storage and shipping 
more convenient and economical. Reconstitution with water produces an 
acceptable mashed potato, but the formulation of shaped potato products, 
such as fries or chips, requires the addition of a binder to form a dough, 
and the implementation of one or more novel process steps. U.S. Pat. Nos. 
3,297,450, 3,539,356, 3,687,679, 3,753,735, 3,800,050, 3,935,322, 
3,997,684, 3,998,975, 4,005,139, 4,082,855, 4,140,803, 4,221,842, and 
4,238,517 are illustrative of various approaches which have been used in 
forming a fry or chip from a dough. An extrusion or sheeting step is 
normally required to achieve the required shape and thickness of a fry or 
chip. The dough must be formulated to be easily spread to the desired 
thickness, to resist sticking to the belt or roller, to be cleanly cut by 
a die, and to resist clumping during frying. Frequently, the resultant 
product lacks the characteristic flavor and mouth feel of a good potato 
chip made by the traditional methods of slicing, washing, and frying the 
slice. 
"Lecithin" is a generic name for a class of compounds which are mixed 
esters of glycerol and choline with fatty acids and phosphoric acid. 
Lecithin is present in eggs, but the predominant product in commerce today 
is prepared primarily from soybeans. Commercial soybean lecithin also 
contains cephalins (an analog of lecithin in which ethanolamine or serine 
is substituted for choline) as well as inositol, phosphatides, 
carbohydrates and traces of other substances. Lecithin is readily soluble 
in mineral oil but poorly soluble in vegetable oils. It is insoluble in 
water but forms an emulsion with water in certain concentrations. One use 
of soybean lecithin is as an emulsifying agent in oleomargarine and 
mayonnaise. Lecithin is also added in small amounts in doughs for baking, 
but is not used for doughs which are fried in deep fat or oil because the 
lecithin decomposes at high temperatures to produce free fatty acids among 
other products. Since many liquid lecithin preparations also include 
excess free fatty acids to solubilize the lecithin for easier handling 
(Kirk-Othmer Encyclopedia of the Chemical Industries, Vol. 12, p. 351, 
1967 Edition), the use of lecithin in fried foods has historically been 
avoided, since it causes a buildup of free fatty acids and darkening of 
the cooking oil. Addition of powdered lecithin to food products that are 
fried during their production results in rapid free fatty acid increases 
as well as significant oil darkening rendering the oil unsuitable after 
only a few hours. Prior to this invention there were no known methods for 
preventing such deterioration. Products which contain free fatty acids 
turn rancid quickly and cannot be shipped and stored for an acceptable 
period of time. As a result, the superior emulsifying properties of 
lecithin routinely employed by bakers have been unavailable to producers 
of fried dough-based foods, and less effective chemicals such as 
monosubstituted glycerides have been substituted, with less satisfactory 
results. 
SUMMARY OF THE INVENTION 
The present invention provides a novel process for the preparation of a 
dough for the production of fried snack foods. The process involves the 
addition of a lecithin-in-water suspension containing lecithin in a range 
of about 0.20 to 0.70% to the dough containing pregelatinized starch, dry 
flaked or powdered cereal or flakes of a starchy vegetable, and water, 
vegetable oil and flavorings. The resultant dough is easily formed by 
sheeting, followed by die cutting and frying so as to resemble a chip 
prepared by traditional methods directly from the vegetable.

DETAILED DESCRIPTION OF THE INVENTION 
The dough for a dough-based fried food product typically consists of flour 
or flake of the chosen grain or vegetable and vegetable oil, water and 
flavorings. When a low starch flour or flake is employed, a processed 
starch in either gelatinized or ungelatinized form is frequently added. 
Water is required to soften the flour and, depending on the protein 
content of the flour, to form a network of protein (gluten) which is the 
framework of the product. Starch, which is present in flours, especially 
potato, corn and bean flour, is used as a binder and is required for the 
unleavened product to expand on frying. Starch also absorbs chemicals from 
the cooking oils which contribute to the flavor of the fried product. Oils 
may be added to the dough to control the stickiness of the dough and to 
control the hardness of the cooked product by controlling the extent of 
the protein framework. 
Doughs used for the manufacture of fried chip-type products must be formed 
in thin, relatively homogeneous layers. This is normally accomplished in 
an automated process, by "sheeting", i.e., placing the dough on a smooth 
surface and rolling the dough to the desired final thickness. The dough is 
prepared by adjusting the ratios of components and the mixing time to 
allow it to sheet uniformly at the desired thickness, without sticking or 
tearing. Control of the dough thickness is particularly important in 
manufactured potato chips because the product is compared in texture and 
color to the product made from sliced potatoes. Emulsifying agents are 
used to achieve a uniform distribution of oil and water in the dough. 
Although fatty acid esters of glycerol have been used in some published 
formulations, it has been found that soybean lecithin is superior in 
achieving the desired dough plasticity in a non-sticky formulation. Direct 
addition of lecithin in dry form to the dough produces a satisfactory 
dough sheet and fried chip but causes a buildup of fatty acids in the 
vegetable-based frying oil and consequent darkening of the frying oil. 
It has surprisingly been found that when lecithin is added to the dough 
during mixing, as a fairly concentrated lecithin suspension (1-5% w/v) in 
sufficient quantity to achieve the desired dough properties, free fatty 
acid buildup in the fryer is avoided. Additionally, the frying oil quality 
is maintained, i.e., severe oil darkening, rendering it unsuitable for 
further use in a few hours, does not occur. Furthermore, clumping of the 
product during frying, as high as 30% when using formulations not 
containing lecithin, is remarkably reduced when lecithin emulsion is 
included in the mix. 
The emulsion is formed by stirring dried lecithin powder free of excess 
fatty acids into water, such that when the emulsion is added to the 
remaining ingredients of the mix, the concentration of lechithin based on 
the dry mix weight being at or above about 0.02% by weight, but below 
about 0.70% by weight. It has been found that lecithin at concentrations 
of less than about 0.02% by weight based on the dry mix weight does not 
significantly reduce clumping, and at concentrations at or above about 
0.69% by weight, the dough sheet becomes lacy and unmanageable due to 
tearing and breaking. Preferably, the lecithin emulsion results in 
lecithin concentration of from about 0.20% to about 0.60% by weight 
relative to the dry mix weight, although lecithin concentrations at above 
about 0.25% by weight do not result in a further improvement in resistance 
to clumping. Most preferably, the concentration of lecithin relative to 
the dry mix weight is from about 0.20% to about 0.25% by weight. At a 
concentration in this range, clumping of the product during frying is 
reduced from about 30% to about 3% when compared to similar formulations 
without lecithin (see FIG. 1). 
As one example of the benefits achieved by the present invention, when 
about 0.2% lecithin in water was used in the preparation of the dough, 
free fatty acid concentration in the frying oil reached a plateau after 10 
hours and increased only very slightly thereafter during the normal useful 
life of the oil. This may vary with different fryers, production rates, 
etc. In contrast, when dry lecithin is used in the dough, the free fatty 
acid concentration increases linearly with time after the first hour and 
the oil is unusable after 6 hours due to darkening, and free fatty acid 
buildup occurs. 
A particularly advantageous result of the practice of this invention is the 
energy-saving which results from the properties of the dough which 
contains as little as 0.05% lecithin. The dough exits evenly from a 
continuous mixer and sheets without sticking to the roller. Approximately 
1/3 less energy is consumed in the sheeting process, as measured by motor 
amperage, than is required when no lecithin is present. 
This invention has been described with particular emphasis upon the 
manufacture of potato chips, but is also applicable to the production of 
other dough-based snack foods. Examples, which are not intended to be 
limiting, include snack foods containing corn, beans, rice, and wheat and 
which may include any approved natural or synthetic flavoring. The 
following example illustrates the applicability and advantages of the 
present invention, without intending to be limiting thereof. 
EXAMPLE 1 
Raw materials (30% modified food starch, 2% sugar, 0.6% salt, 0.3% oil and 
67% potato flakes) are first blended together in a ribbon blender. The 
resulting essentially dry mix is then transferred via vacuum to a large 
hopper. The dry mix is metered from this hopper into a Wenger mixer by use 
of an Acrison volumetric feeder. A 2.5% (w/v) lecithin/water suspension is 
introduced into the dry mix shortly past the mixer entrance. The remainder 
of the water necessary for proper dough formation is then added in the 
Wenger mixer slightly after the addition of the lecithin/water suspension. 
The resulting dough is sheeted on a two-roll sheeter, dried slightly by 
passage through a jet-sweep oven, and cut into rectangular pieces by a 
rotary cutter. After frying in vegetable oil, the chips are oil sprayed in 
a tumbler to increase oil content, cooled on a cooling conveyor, salted or 
seasoned and packaged. 
The lecithin/water suspension is prepared by vigorously mixing 100 g. of 
powdered lecithin with 4,000 mls. of water in a large blender. This 
suspension is added at a rate that results in a concentration of 0.23% 
lecithion based on the dry mix weight. 
It will be appreciated that modifications of the present invention, within 
the skill of those familiar with the cooking arts, can be undertaken 
without departure from the spirit or scope of this invention.