3种改性方法对琼胶理化性质的影响

文章采用羧甲基化、过氧化氢氧化和羟丙基化3种方法对琼胶进行改性,通过比较表征改性前后琼胶的溶解性能、色泽、凝胶透明度、凝胶质构特性、IR分子结构和热稳定性,探究不同改性方法对琼胶理化性质的影响。结果显示,羧甲基化和羟丙基化后琼胶的溶解温度、凝胶温度、凝胶再溶温度和凝胶强度显著降低(P<0.05),琼胶凝胶软弹性和持水性增强;氧化改性显著提高了琼胶凝胶强度(P<0.05),由984 g·cm^-2提高至1463 g·cm^-2;氧化改性和羟丙基化改性显著提高了琼胶的白度(P<0.05),而羧甲基化改性显著降低了琼胶白度(P<0.05);3种改性方法均显著提高了琼胶凝胶的透明度(P<0.05);羧甲基化改性降低了琼胶的热稳定性,氧化和羟丙基化改性提高了琼胶的热稳定性。由此证明3种改性方法可不同程度地改变琼胶的理化性质。

Effect of three modification methods on physicochemical properties of agar

In this study,agar was modified by carboxymethylation,hydrogen peroxide oxidation and hydroxypropylation to compare the solubility,color,gel transparency,gel texture,IR molecular structure and thermal stability before and after the modification,aiming to explore the influence of three modification treatments on the physicochemical properties of agar.The results show that the dissolving temperature,gelling temperature,melting temperature and gel strength decreased significantly after carboxymethylation and hydroxypropyl treatments(P<0.05),whereas the soft elasticity and water holding capacity of agar gel improved;the gel strength of agar was improved by oxidation treatment(P<0.05),from 984 g·cm^-2 to 1463 g·cm^-2;after oxidation and hydroxypropylation,the modified agar showed higher whiteness(P<0.05),while carboxymethyl agar was on the contrary(P<0.05).Besides,all modifications had increased the transparency of agar gel significantly(P<0.05).The thermal stability increased with oxidation and hydroxypropylation,but reduced with carboxymethylation.In conclusion,three modification methods can improve physicochemical properties of agar at different extents.