Bioavailability of carbohydrate material stored in tropical fruit seeds

Abstract

Properties of starches derived from seeds obtained from tropical fruits used by the pulping industries were characterised and their response to enzyme attack ascertained. Despite similarity of the tissue from which starch was obtained, seeds starches varied depending upon the botanical source in all of the structural and physicochemical properties measured except in the pattern by which enzymes attack the native granule. Morphologically the granules were very different, possessing a variety of shapes and sizes; the composition and size of the macromolecular fractions were also distinct. The hydration properties and susceptibilities of the granules were found to be different, which was surprising considering the similarity in physiological function of the starches. Similarly, the susceptibility of intact granules to enzyme attack was different in extent, though all of the granules should undergo a similar pattern of attack, namely surface erosion. Correlation analysis revealed an apparent lack of correlation between the enthalpy of gelatinisation, assumed to represent degree of crystallinity, and enzyme susceptibility or swelling. It was concluded that, despite the existence of an underlying mechanism of hydrolysis, shaving of the granule surface and structural characteristics unique to a particular species may dominate.