磷钨杂多酸的固定化及其酯化黑米花青素的研究

Studies on Immobilization of Phosphotungstic Heteropoly Acid and Its Esterification of Black Rice Anthocyanins

黑米花青素具有良好的抗氧化活性,然而其高度水溶性,限制了其在油脂体系中的应用。为提高普通黑米花青素的抗油脂氧化性能,首先制备基于SBA-15的固定化磷钨杂多酸,然后以其为催化剂,用于黑米花青素的酯化反应中,得到脂溶性黑米花青素。通过X-射线衍射仪及透射电镜等表征手段,验证磷钨杂多酸成功进入SBA-15孔道内进行固定化。以酯化率为考察指标,探究黑米花青素与乙酸酐配比、杂多酸催化剂添加量、酯化反应温度和时间的关系,同时对黑米花青素分子结构进行初步表征分析并探讨了油脂抗氧化特性。结果表明:在反应物配比1∶2、催化剂用量2.5%、反应温度95.0℃,反应时间4.5 h条件下,酯化率达93%,回收率在80%以上。酯化后黑米花青素的脂溶性明显提高,出现酯羰基C=O键和酯基的特征吸收峰,说明增加了新的酯基官能团,改善了黑米花青素的亲脂性,显著提高了黑米花青素的抗油脂氧化效果。试验研究了脂溶性黑米花青素在一级大豆油中的长期抗氧化性,结果表明在相同添加量的情况下,脂溶性黑米花青素的抗氧化性要高于普通黑米花青素及维生素E,低于特丁基对苯二酚。

Black rice anthocyanin has good antioxidant activity,but its high water solubility limits its application in oil system.In order to improve the anti-oxidation performance of ordinary black rice anthocyanins,immobilized phosphotungsten heteropoly acid based on SBA-15 was prepared.The immobilized phosphotungsten heteropoly acid was used as catalyst in the esterification of black rice anthocyanins to obtain oil-soluble black rice anthocyanins.In this paper,X-ray diffraction and transmission electron microscopy were used to verify that phosphotungstic heteropoly acid could be successfully immobilized in SBA-15 channel.The esterification rate was taken as the inspection index,the relationship between the ratio of black rice anthocyanin to acetic anhydride,the amount of heteropoly acid catalyst,the temperature and time of esterification were studied.At the same time,the molecular structure of anthocyanins from black rice was preliminarily characterized analysis and the antioxidant properties of oils were discussed.The results showed that under the conditions of 1∶2 reactant ratio,2.5%catalyst dosage,95.0℃reaction temperature and 4.5 h reaction time,the esterification rate was about 93%and the recovery rate was over 80%.After esterification,the liposolubility of black rice anthocyanins was significantly improved,and the characteristic absorption peaks of C=O bond and ester group appeared.This indicated that the addition of new ester functional groups improved the lipophilicity of black rice anthocyanins,thus significantly improving the anti-lipid oxidation effect of black rice anthocyanins.The long-term antioxidant activity of oil-soluble black rice anthocyanins in primary soybean oil was preliminarily studied.The results showed that the antioxidant activity of oil-soluble black rice anthocyanins was higher than that of ordinary black rice anthocyanins and VE,and lower than TBHQ at the same addition amount.