Submitted to: Food Technologists Institute
Publication Type: Abstract Only
Publication Acceptance Date: 6/20/1995
Publication Date: N/A
Technical Abstract: The indigestible starch fractions of dry bean seeds (Phaseolus vulgaris) have been studied by examining the raw and cooked seeds enzymatically and microscopically. It is generally recognized that the indigestible starches in dry beans are primarily composed of the ungelatinized starch and retrograded starch fractions. The degree of gelatinization of whole beans differentially prepared by cooking in either water or thermally processed in tin cans was evaluated. An enzymatic procedure using B- amylase and pullulanase was used to selectively digest the starch fractions. The results obtained were correlated with those obtained from a polarized light microscope. Large portions of ungelatinized starch granules, showing birefringence under polarized light, were observed even in fully-cooked whole beans prepared in an open kettle (boiled/2hrs). Ungelatinized starch granules were observed to be entrapped in parenchyma a cells. The indigestible starch component of whole beans was evaluated with three different sampling and preparation procedures [1) fresh cooked, 2) fresh cooked-refrigerated and 3) fresh cooked-lyophilized] to examine their effect on retrogradation. There were no significant differences in the amount of indigestible starch among these procedures. Ungelatinized starch and retrograded starch fractions were associated with the intrinsic degree of gelatinization observed and the subsequent indigestible starch components present in whole cooked beans.