Chemical modification of oat flour starch and protein and assessment of the physical characterisrics of a cake prepared using them

Due to their nutritionally favorable proprties، including high protein، fat and β glucan contents and a desirable amino acid composition، oats have attracted much attention for human consumption. In this research، starch and a protein-isolate were extracted from husked oats، modified and added as ingredients in cake flour used for baking cake. Starch and protein isolated from oats were chemically modified، the former by cross-linking and acetylation and the latter by deamidation and succinylation. Oat flour formulations were prepared using different levels of the modified starch and protein isoltes and the physical characteristics of the cakes prepared from them determined. Cross-linking brought about a decrease in the swelling power of starch granules and an increase in syneresis (p<0. 001)، but it had not significant effect on gelatinization temperature. Acetylation، on the other hand، increased the granules swelling power (p<0. 001)، but it decreased gelatinization temperature and syneresis (p<0. 001). As regrds protein، both deamidation and succinylation increased the emulsifying activity and nitrogen solubility index but reduced foaming capacity and emulsion stability (p<0. 001). The prepared cake of oat flour has lower batter viscosity (p<0. 001) and higher volume (p<0. 001) than prepared cake of wheat flour. In the cake with Acetylated starch، increase in level of substitution led to increase in batter viscosity (p<0. 001) and cake volume (p<0. 001). Increasing in level of deamidated protein produced cake with lower batter viscosity (p<0. 001) and higher volume (p<0. 001)، but increase in level of succinylated protein increased batter viscosity and volume (p<0. 001) of cake. Simultaneous use of acetylated starch and deamidated protein resulted in a cake batter with a higher viscosity and lightness as compared to control. Therfore، substitution of oat flour with acetylated starch or acetylated starch and deamidated protein will result in improvements in the physical characteristics of oat cake.