Heat-moisture treatment and acid hydrolysis of corn starch in different sequences

•Corn starches were acid hydrolyzed and heat-moisture treated in two sequences.•The sequence of dual treatments deeply affects the physicochemical properties.•Acid hydrolysis after heat-moisture treatment results in more thermostable starches.•Perfection and destruction do vary during different stages of dual modifications.

Dual modification of corn starch was carried out by combining acid hydrolysis (AH, 6, 12, 24 h) and heat-moisture treatment (HMT, 15, 30, 60 min) in different sequences (AH-HMT and HMT-AH). X-ray diffractometry, differential scanning calorimetry, polarized light microscopy, and rheometer were used to characterize the differences in molecular structure and physicochemical properties resulting from the sequences. Both AH-HMT and HMT-AH sequences increased the metastability of the starch granules. Starch hydrolyzed by AH for 12 h and then subjected to HMT for 15 min (AH12-HMT15) has onset, peak, and conclusion gelatinization temperatures that were 4.2, 3.9 and 6.4 °C higher than those of HMT15-AH12 one, respectively. The relative crystallinity of HMT15, 30-AH decreased as AH time increased; however, it increased in the HMT60-AH sample. Besides, all the temperature ranges of gelatinization of AH-HMT15, 30 were higher than those of HMT15, 30-AH, but lower in the case of AH-HMT60 when compared to HMT60-AH. This indicates that the perfection effect became more prominent over destruction on HMT60 for AH-HMT samples. The AH-HMT sequence also resulted into lower relative crystallinity, swelling power, solubility, gelatinization enthalpy, and pasting viscosity than in those samples produced using HMT-AH sequence.