Morphological structure and crystallinity of ‘Rainha’ sweet potato starch by heat–moisture treatment

Abstract Heat-moisture treatment is type of physical modification that which cause changes in the technological characteristics of the starch. One of the sources of starch that presents potential of use of this treatment is sweet potato of the variety 'Rainha' (Ipomoea batatas). Therefore, the objective of this work was extract the sweet potato starch, apply the heat-moisture treatment in different relative humidity conditions (15, 20, and 25%), and characterize the starches as to water absorption capacity, morphology and crystallinity. Starch extracted from sweet potato resulted in a product of high purity. All modified starches showed a higher water absorption capacity when compared to native starch. The morphology of the starch granules remained unchanged after the modification and the same was observed with respect to the crystallinity. However, modified 15% moisture starch showed significant changes in the amylose content, water absorption, and crystallinity, these characteristics extend the use of this starch, for use in foods.