Starch Granules Size Distribution of Sweet Potato and Their Relationship with Quality of Dried and Fried Products

To understand the quality characteristics of different varieties of starch granules from sweet potato and their relationship with processing adaptability, 21 typical sweet potato varieties cultivated at Zhejiang A&F University are used to study grain size using a Mastersizer 3000 laser particle size analyzer. Our results are as follows: 1) The volume distribution of starch granules is a bimodal curve and the grain size is 2.27 μm. Starch granules with a particle size <2.27 μm are defined as small starch granules, starch granules with a particle size of 2.27–17.51 μm are defined as medium starch granules, and starch granules with a particle size >17.51 μm are defined as large starch granules. 2) The contents of total starch, amylose, and amylopectin are negatively correlated with the volume percentage of middle-sized (r = −0.611**, −0.489**, and −0.529**) starch granules but positively correlated with large-sized (r = 0.628**, 0.544**, and 0.517**) starch granules. 3) In processing applications of sweet potato, the cohesiveness of dried sweet potato is improved and hardness of dried sweet potato decreases with the increase of small- and medium-sized starch granules content. The color, fragrance, exterior, and taste of sweet potato chips are improved with the increase of small- and medium-sized starch granule content. Above results could help understand relationships between granule size and final product quality.