Expanded products with high protein content

Abstract

High protein expanded products are produced by extrusion with unique blends of ingredients, such as wheat protein isolates, modified wheat starch, salts, gums and moisture. The mixture is extruded in a twin-screw extruder with the temperatures in the range of 50 to 140° C., screw speeds of 250 to 450 rpm and with a back pressure of 350 to 1200 psi for different recipes. A range of expanded wheat crisps and other expanded products with wheat protein contents ranging from 30 to 90% are obtained from this process. The expanded products have good cell structure with varying cell sizes when viewed under a microscope. This process can be used to develop a varied range of products such as, wheat crisps, wheat curls, wheat loops etc. The products may be used in nutritional or health bars and other comestible having a high protein and low carbohydrate content.

We claim: 
     
         1 . An expanded food product comprising:
 a wheat protein isolate in an amount ranging from 50% to 75% by weight, the isolate being formed by dissolving wheat gluten in an aqueous solution and isolating the wheat protein components, the isolate having a protein content of at least 85% by weight;   an oxidized starch in an amount ranging from 19% to 49% by weight, the starch being oxidized by converting hydroxyl groups on a starch to carbonyl and carboxyl groups;   wherein the product contains no appreciable added fiber;   wherein the cell structure of the product has a substantially uniform distribution of cell sizes and cell wall thicknesses; and   wherein mixing of product ingredients has occurred to substantial homogeneity such that there is no appreciable transition of protein to starch.   
     
     
         2 . The product of  claim 1 , further comprising a cross-linked hydroxypropylated starch, the starch being made by reacting a starch with propylene oxide and crosslinking the product. 
     
     
         3 . The product of  claim 2 , wherein the cross-linked hydroxypropylated starch is present in an amount ranging from 8% to 38% by weight. 
     
     
         4 . The product of  claim 1 , further comprising a non-fibrous RS4 resistant starch made by a process of crosslinking by phosphorylation. 
     
     
         5 . The product of  claim 2 , further comprising a non-fibrous RS4 resistant starch made by a process of crosslinking by phosphorylation. 
     
     
         6 . The product of  claim 1 , further comprising a non-fibrous reversibly-swellable RS4 resistant starch made by a process of swelling followed by crosslinking by phosphorylation. 
     
     
         7 . The product of  claim 2 , further comprising a non-fibrous reversibly-swellable RS4 resistant starch made by a process of swelling followed by crosslinking by phosphorylation. 
     
     
         8 . The product of  claim 1 , further comprising an oxidized non-fibrous reversibly-swellable RS4 resistant starch made by a process of swelling followed by crosslinking by phosphorylation followed by oxidation. 
     
     
         9 . The product of  claim 1  in which the wheat protein isolate is present in an amount ranging from 65% to 75% by weight. 
     
     
         10 . The product of  claim 1  in which the wheat protein isolate has a protein content of at least 90% by weight. 
     
     
         11 . The product of  claim 1  having a final moisture level of less than 8%. 
     
     
         12 . An expanded food product comprising:
 a wheat protein isolate in an amount ranging from 50% to 75% by weight, the isolate being formed by dissolving wheat gluten in an aqueous solution and isolating the protein components;   a cross-linked hydroxypropylated starch in an amount ranging from 8% to 38% by weight, the starch being made by reacting a starch with propylene oxide and crosslinking the product;   wherein the product contains no appreciable added fiber;   wherein the cell structure of the product has a substantially uniform distribution of cell sizes and cell wall thicknesses; and   wherein mixing of product ingredients has occurred to substantial homogeneity such that there is no appreciable transition of protein to starch.   
     
     
         13 . The product of  claim 12 , further comprising a non-fibrous RS4 resistant starch made by a process of crosslinking by phosphorylation. 
     
     
         14 . The product of  claim 12 , further comprising a non-fibrous reversibly-swellable RS4 resistant starch made by a process of swelling followed by crosslinking by phosphorylation. 
     
     
         15 . The product of  claim 12 , further comprising an oxidized non-fibrous reversibly-swellable RS4 resistant starch made by a process of swelling followed by crosslinking by phosphorylation followed by oxidation. 
     
     
         16 . The product of  claim 12  in which the wheat protein isolate is present in an amount ranging from 65% to 75% by weight. 
     
     
         17 . The product of  claim 12  in which the wheat protein isolate has a protein content of at least 90% by weight. 
     
     
         18 . The product of  claim 12  further comprising an oxidized starch. 
     
     
         19 . The product of  claim 17 , wherein the oxidized starch is present in an amount ranging from 19% to 49% by weight. 
     
     
         20 . The product of  claim 12  having a final moisture level of less than 8%.