Physico-Chemical Properties of A-and B-Type Starch Granules in Wheat

A-and B-type starch granules were isolated and purified from wheat(Triticum aestivum L.) flour to study their physico-chemical properties.Starch granule image of scanning electron microscopy(SEM) showed that there was obvious morpho-logical difference between A-and B-type starch granules,and they could be completely isolated without mixture due to the unique type of starch granule in each group.The diameter of A-type starch granule was 4.45-44.46 μm and there were 1.23×1010 granules per gram starch,whereas the two values of B-type granule were 0.47-11.16 μm and 6.70×1010,respectively.Amylose content in A-and B-type granules was 27.70% and 22.62%,respectively.Compared with the A-type granules,the B-type granules had higher pasting temperature and lower viscosities of peak,breakdown,and setback.The B-type granules contributed greatly to the pasting properties of the reconstituted starches when the fraction of B-type granules was less than 30%.Effects of starch granule size distribution on pasting property of reconstituted starch decreased when the fraction of B-type granules was higher than 30%.