Effect of tea polyphenols on the retrogradation of sweet potato starch

Retrogradation in cooked starch based products significantly shortens the shelf life of these products as they become firm and less elastic during storage. In this work, the effect of tea polyphenols ( TPs) on the retrogradation of sweet potato starch during long- term storage ( 80d) was evaluated by characterizing sweet potato starch sample using X- ray diffraction ( XRD) , texture profile analysis ( TPA) , color analysis, and Fourier transform infrared spectroscopy ( FT- IR) .After storage for 80 d, the hardness of pure sweet potato starch increased to about30 times of initial hardness.While for sweet potato starch with 9wt.% TPs, the normalized hardness was less than 4.The experimental results showed that TPs retard the recrystallization of starch, resulting in decrease in the hardness of sweet potato starch gel.The variations of hardness and color of the sweet potato starch gel were also limited by the addition of TPs.The results suggested that the retrogradation of sweet potato starch was inhibited by TPs.