Properties and Characterization of Cross-linked Purple Potato Starch with Different Degrees of Substitution

In this study, cross-linked purple potato starch was prepared from purple potato starch and a mixture of sodium tripolyphosphate and sodium trimetaphosphate as crosslinking agent, aiming at studying the effect of different degrees of substitution (0.0053~0.0212) on cross-linked starch, determining and characterizing the properties of cross-linked purple potato starch with different degrees of substitution. The results showed that with the increase of degree of substitution, the cross-linked purple potato starch of transparency and solubility degree boosted, swelling degree decreased, and freezing-thaw stability increased. The surface of purple potato starch was intact and smooth, but the cross-linked purple potato starch presented a stripped-off appearance. The force of interparticle of cross-linked purple potato starch increased, and the adhesion and aggregation of cross-linked purple potato starch represented obviously. All the crystallization of samples was C-type, the average particle size of cross-linked purple potato starch was not significantly different compared with purple potato starch, but the crystallinity decreased with the increase of degree of substitution. The negative charge of cross-linked purple potato starch also increased with the increased degree of substitution. Therefore, the properties of cross-linked purple potato starch were greatly improved compared with purple potato starch and were closely associated with degree of substitution, which provided theoretical basis for the further development of purple potato resources.