Indigestible fraction and starch availability in peas measured in vitro

The size of the indigestible fraction of, and the availability of starch in, commercial frozen and canned peas was studied in vitro. The total dietary fibre content, as determined by chemical analysis, was similar in both samples (27%); nevertheless, appreciable amounts of resistant starch (4.4-6.9%) and resistant protein (4.7-5.4%) were found in the insoluble dietary fibre gravimetric residue. Other indigestible components of the pea were an additional fraction of resistant starch, not associated with insoluble dietary fibre, and the oligosaccharides inulin and stachyose. The total amount of starch (25.8-36.1%) was very different between frozen and canned samples, and was inversely correlated with their sucrose contents (14.2-6.7%). Our results indicate that 35-40% of the dry weight of peas is not digested in vitro and that the relative rate of glucose release by alpha-amylase hydrolysis seems to be decreased in the presence of resistant starch.