Morphological, hydrolytic and thermal properties of legume starches

Abstract

Legumes are an excellent source of carbohydrate and provide an inexpensive source of protein. With the exception of beach pea (12.3%), the percentage yields of extracted legume starches fall within the range of 18.0-45.0% on a whole seed basis. The total lipid contents of legume starches range from 0.01-0.87%. Legume starches have variable granule diameters, generally between 4 and 80 μm. Granule shape may be oval, spherical, elliptical or irregular, depending on the source. Legume starches exhibit a two-stage solubilization pattern; the rates of hydrolysis for the first and second stages are identical in some legume starches but differ in others. Most legume starches exhibit C-type X-ray diffraction patterns. The degrees of crystallinity of most legume starches are similar to, or slightly lower than, those of cereal starches. Most legume starches exhibit nearly identical gelatinization transition temperatures and enthalpies. However, their gelatinization temperature ranges (Tc - To) differ. Legume starches easily retrograde due to their relatively high amylose contents, although long term retrogradation is attributed to short chains of amylopectin.