Composition and physicochemical properties of oat starches

Abstract

Starches from two new oat varieties namely AC Stewart (Avena sativa L.) and NO 753-2 (Avena nuda L.) were isolated and some of their characteristics determined. The total amount of starch lipids (TSL) extracted by acid hydrolysis was 1.60% (w/w) in both starches. The free lipid content (extracted by chloroform-methanol (CM) 2:1 v/v at 25°C) was 0.36 and 0.30% (w/w) in NO 753-2 and AC Stewart starches, respectively. The bound lipid content (extracted by hot n-propanol-water 3:1 v/v from the residue left after CM extraction) was 1.27 and 1.37% (w/w) in NO 753-2 and AC Stewart starches, respectively. The total amylose contents were nearly the same (~23%, w/w) in both starches, of which 14.1 (NO 753-2) and 15.3% (AC Stewart) were complexed by native lipids. The starches differed widely in their degree of swelling, gelatinization transition temperatures and enthalpy, susceptibility towards acid and enzyme hydrolysis, gel strength, paste viscosity, thermal stability and retrogradation characteristics. The results suggest that the extent of interaction of starch chains within the amorphous and crystalline regions of the granule was stronger in NO 753-2 than in AC Stewart.