Influence of genotype and processing on the in vitro rate of starch hydrolysis and resistant starch formation in peas (Pisum sativum L.)

The formation of resistant starch (RS) and the rate of starch hydrolysis we re evaluated in vitro in a wild type of green-seeded pea genotype RRRbRb BC 3 (33-Am) with 32.7% amylose content and in two mutants RRrbrb BC3 (23-Am) and rrRbRb BC3 (65-Am) with amylose contents of 23.3 and 65.1%, respectivel y. Pea samples were intact or homogenized and subjected either to autoclavi ng or to boiling at atmospheric pressure. The amount of RS (total starch ba sis) varied from 6.2 to 12.9% in the 23-Am products and from 31.2 to 33.4% in the 65-Am products. The RS level of the 33-Am product with a regular amy lose content was 11.0%. Both the 23-Am and the 65-Am products were abundant sources of dietary fiber (39 and 34%, dry matter basis, respectively) vers us 23% in the regular pea product. The amylose/amylopectin ratio was an imp ortant determinant of the rate of starch hydrolysis. The hydrolysis indices (HI) and predicted glycemic indices were lowest in the 65-Am peas (HI rang e = 42-59) as compared to the 23-Am peas (HI range = 53-84). It is conclude d that the pea genotypes covered a wide range in starch availability, which is likely to affect nutritional parameters such as glycemic responses and colonic delivery of starch.