Heat moisture treatment modifies amaranth, quinoa, and taro starches via reorganizing granular architecture and driving aggregation.

Amaranth, quinoa, and taro starches have very small granule sizes, which are desirable in certain applications. Heat-moisture treatment (HMT) could modify their properties by changing the granular architecture but maintain the technical advantages related to small granule size. The study intended to investigate how starch structure modulated the diverse HMT modifications. The results suggested that, beyond the granular size, both amylose and amylopectin played important roles in the HMT modification of starch. Upon HMT, amylose might strengthen the packing of starch granules via interacting with amylopectin. Unit chains with chain lengths of 13-24 glucose residues and fingerprint B-chains in amylopectin were negatively related to the reduction of ordered structures upon HMT. Using a method newly developed based on the building block-backbone model, the HMT-induced alteration in the conformation of the branched backbone of amylopectin was characterized. For maize and taro starches, the HMT had relatively conservative effects on the branch distribution in starch granules. The branch distribution in the granule of potato starch was altered upon the transformation of its polymorphism. HMT resulted in severe aggregation of small-granule starches, which exerted a superimposed effect on the modification of starch properties.