Effects of Konjac Gum on Physicochemical, Rheological, Textural Properties, and In Vitro Digestibility of Purple Potato Starch

Abstract Adding hydrocolloids into native starch is a secure and valid method of physical modification. However, few research focuses on the interactions between konjac gum (KGM) and purple potato starch (PPS). In this study, the effects of KGM on the physicochemical, rheological, textural properties, and in vitro digestibility of PPS are evaluated. The swelling power, solubility, transparency, zeta potential value, particle size, gel adhesiveness, and cohesiveness of PPS are enhanced with increasing KGM content. The results show the combination of PPS and KGM exhibits a higher adhesiveness and a denser structure than that of PPS alone. Static rheological analysis shows PPS/KGM composites exhibit pseudoplastic and shear thinning enhancement behaviors with the rise of the KGM content from 0% to 2.5%. Dynamic rheological analysis reveals that storage modulus ( G ') > loss modulus ( G ″), mainly showing elastic behavior, and G ′, G ″, and the loss tangent (tan δ ) increase with the rise of the KGM content from 0% to 2.5%. Fourier transform infrared spectroscopy analysis shows stronger hydrogen bonding of PPS/KGM complexes compared to PPS only. Moreover, KGM increases the contents of resistant starch. All these findings indicate that KGM can improve the functional properties of PPS.