Composition, structure, morphology and physicochemical properties of lablab bean, navy bean, rice bean, tepary bean and velvet bean starches.

Abstract

The composition, morphology, structure and physicochemical properties of starches from lablab bean, navy bean, rice bean, tepary bean and velvet bean were examined. Starch yield (on a whole seed basis), total lipid, apparent amylose (AM) and starch damage were in the range 20.6-29.9%, 0.48-0.62%, 22.1-32.1% and 0.004-0.011%, respectively. Difference in amylopectin chain length distribution amongst the starches was marginal. The starches differed significantly with respect to granule morphology, molecular order, molecular orientation, double helical content, gelatinization parameters, swelling factor, AM leaching, thermal stability and enzyme hydrolysis. The results showed that interplay amongst differences in molecular order, double helical content, relative crystallinity, AM content, granule morphology and the extent of interaction between and amongst starch chains within the amorphous and crystalline domains, influenced thermal, rheological and digestibility properties.