the concept of this invention pertains broadly to a process for producing protein - based snack food products . the protein source material may be any of the high purity protein sources which form upon hydration , an irreversible gel such as oilseed protein isolates . soy protein isolates containing at least about 90 % protein on a dry basis are preferred . an aqueous slurry containing at least about 20 % protein solids is prepared and mechanically worked from a sticky paste or dough into a continuous plastic gel . this indicates that the protein is fully hydrated . the gel is then subjected to cooling action sufficient to form ice crystals of the free water , e . g ., freezing . the gel is formed into the desired shape either before or after freezing . the product is then dried sufficiently to melt the ice crystals and drive off such moisture while partially heat setting the protein . thorough drying of the product throughout its cross section is necessary ( without surface skin formation ) thus slower drying rates are advantageous . for example , temperatures of 180 ° to 250 ° f . are advisable . the desired dryness is from about 5 to 20 %, and preferably 8 to 10 %. finally , the product is immersed into hot oil and deep fat fried at conventional frying temperatures , wherein the product will expand or puff . the product has excellent structural integrity and a cripsy cellular structure . however , without the freezing and drying the procedure leads to a soft crumbly product of little structural integrity and little desirability as a snack product . the end product is typically characterized by containing at least 40 % protein , less than 50 % fat of absorption and about 2 % water yet it retains excellent structural integrity without the need of a starch or binder . it should be understood that salt and various flavorings can be added . the following examples are intended to illustrate the invention . one part of soy protein isolate is added to a blending device containing four parts of water and is mixed until full hydration of the soy into a continuous plastic gel is accomplished . two percent salt is dispersed into the mixture . the gel is placed into molds and frozen . the formed product is removed from the molds , thawed and sliced while still partially frozen ( for convenience ). the product is dried at about 200 ° f . until about 8 % moisture remains . then the product is deep fat fried at 400 ° f . for 10 - 15 seconds . the product puff and is pleasingly crispy , cellular with good cohesion and structural integrity . the same as example i except that after hydration of the protein , the product was refrigerated overnight rather than freezing and drying it . then it was deep fat fried . the product was soft and crumbly with a soggy mouth feel and undesirable as a snack chip or wafer . the same as example i except the product was dried prior to freezing and then fried . the product did not puff and had a soggy middle .
a protein - based snack food product and its method of manufacture are disclosed . the process negates the need for carbohydrate , starch or farinaceous ingredients in the product formulation . yet the product will expand or puff and will maintain its structural integrity during deep fat frying .