科研之友
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摘要
Resveratrol (RES) is a kind of stilbene compound with bioactivities and ultraviolet or heating treatment can weaken its bioactivities by destroying its structure. Pectin is able to form non-covalent bonds with RES, which is conducive to the protection of antioxidant activity of RES. In this study, the structure of pectin was modified by the method of enzymolysis combined with ultrasound treatment. The molecular and microscopic structure of modified pectin was characterized, and the interaction mechanism between pectin and RES was discussed by isothermal titration method. At last, the antioxidant activity of RES-pectin complex under ultraviolet or heating treatment was tested. The results show that enzymolysis combined with ultrasound modification method can remarkably reduce the relative molecular mass and degree of methyl esterification (DM) of pectin. The weight-average molecular mass of pectin (PE45U) modificated by 45-min enzymolysis and ultrasound treatment is only 2% of that of unmodified pectin.SEM images show more irregular fragments of pectin structure after the modification. The enzymolysis-ultrasound modification exposes a great number of -OH of pectin, which considerably increases the interaction sites and affinity between RES and pectin. The interaction sites number between PE45U and RES is 24 times that between unmodified pectin and RES. The antioxidant activity of RES is significantly enhanced after interacting with pectin under ultraviolet or heating treatment (P<0.05). This study provides new insights to solve the problem of poor ultraviolet and thermal stability of RES and other stilbene in food industry.
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