Mechanism of starch gelatinization and polymer leaching during microwave heating

The objective of this study was to investigate the process of gelatinization, granule swelling, and polymer leaching following microwave heating of wheat starch suspensions. Polymer leaching was investigated as a function of heating rate, final temperature and starch concentration. Different heating rates were achieved by changing the mass of the starch slurry heated in the microwave oven and the temperature study was conducted on samples of same weight heated to different final temperatures. The total soluble carbohydrate and amylose content in the supernatant was measured. Granule swelling and leaching of polymers occurred only after complete loss of granule birefringence presenting evidence of an asynchronous process of gelatinization compared to conduction modes of heating. The amount of soluble carbohydrate and amylose in the supernatant increased with the increase in temperature and the amylose leached into supernatant decreased with increasing heating rates.