Succeeded starch nanocrystals preparation combining heat-moisture treatment with acid hydrolysis.

Heat-moisture treatment (HMT) could be applied to increase the relative crystallinity (RC) of raw waxy maize starch (WMS) and mar the dense surface of starch granules. The optimal HMT conditions including temperature, treatment time, and moisture content were determined by response surface methodology (RSM). When the temperature, treatment time, and moisture content were 99.2 °C, 1.8 h, and 18.2%, respectively, the maximum RC of heat-moisture treated starch (HMTS) could reach to 42.44% and more holes, depressions, and cracks appeared on the surface of HMTS. Afterwards, HMTS was subjected to acid hydrolysis to prepare starch nanocrystals (SNCs). It was confirmed that SNCs could be successfully obtained with a hydrolysis time of 4 days and a yield of 26.7%. The results revealed that this method was more effective than conventional sulfuric acid hydrolysis method with a hydrolysis time of 5 days and a yield of 15.7%.