烷基化果胶凝胶性质的研究

Study on Gel Property of Alkylated Pectin

本文研究了蔗糖含量、pH值及钙离子浓度对烷基化果胶凝胶性质的影响。将C_6、C_(12)及C_(18)烷基链引入果胶分子中,通过气相色谱测定了产物的取代度,得到具有不同取代度、相同链长的产物(PC_6S^(1.35),PC_6S^(2.90)和PC_6S^(4.53))和不同链长、相同取代度的产物(PC_6S^(2.90),PC_(12)S^(2.90)和PC_(18)S^(2.90))。通过流变、质构及FT-IR方法考察蔗糖含量、pH值及钙离子浓度对烷基化果胶凝胶性质的影响。结果表明:烷基化果胶的凝胶强度随蔗糖含量和钙离子浓度的增加而增强,随pH值的降低而增强;在蔗糖含量、pH值及钙离子浓度一定时,烷基化果胶的凝胶强度随着取代度和链长的增加而增强,且较高取代度和较长链长的烷基化果胶凝胶强度高于原果胶;提高取代度、取代基的碳链长度以及钙离子浓度均可提高烷基化果胶的凝胶稳定性。此外,随着钙离子浓度的升高,烷基化果胶凝胶的红外吸收峰发生红移且强度增大,说明钙离子与果胶的羧酸基团发生了络合。

The effects of sucrose content, pH and Ca^2+ concentration on the properties of alkylated pectin (ALP) gel were investigated in this study.Pectins were alkylated with alkyl chain (C6, C12, C18) at different degrees of substitution (DS) and the DS was determined by gas chromatography.The pectin derivatives were divided into two groups, one was the derivatives with the different DS but the same chain length named as PC6S^1.35,PC6S^2.90,PC6S^4.53, and another one was the derivatives with the different chain length but the same DS named as PC6S^2.90,PC12S^2.90,PC18S^2.90.The effect of sucrose content, pH and Ca^2+ concentration on gel strength of original pectin and ALP was analyzed by rheological properties, texture properties and FT-IR.The results suggested that the gel strength of ALP was increased with the increase of sucrose content and Ca^2+ concentration, as well as the decrease of pH.When the sugar content, pH and Ca^2+ concentration were constant, the gel strength of ALP increased with the increase of DS and chain length, and the gel strength of ALP with higher DS and longer chain length was higher than that of the original pectin.The higher DS, longer chain length and higher Ca^2+ concentration enhanced the gel stability of ALP.What's more, the FT-IR results observed that the infrared absorption peak was red shift and enhanced indicating the formation of a complex between calcium and ionized carboxylate groups during gelation.