用乙醇提取桑椹花青素的工艺优化及影响产品稳定性的因素分析

Process Optim ization for Ethanol Extraction of Anthocyanins from Mulberry Fruit and Analysis of Factors Influencing Product Stability

花青素是一种天然色素和抗氧化剂,但其易受多种因素影响而发生降解。以桑椹冻干粉为原料,采用乙醇浸提的方法,以花青素得率为考核指标,在单因素试验的基础上采用Box-Behnken设计及响应面试验方法优化桑椹花青素的提取工艺,并对影响桑椹花青素稳定性的因素进行分析。在料液质量浓度为0.073 g/m L、提取剂乙醇体积分数50%、提取液p H 1、提取温度78.02℃、提取时间1.5 h的优化工艺条件下,用桑椹冻干粉提取花青素的得率达到6.93%。采用上述优化工艺提取桑椹花青素在保证提取得率的前提下,更加经济有效。提取的桑椹花青素在p H值为1时稳定性最好,H_2O_2对桑椹花青素有强烈的破坏作用,高浓度的Na_2S_2O_3也会使其发生降解;紫外光、室外自然光、室内散射光对桑椹花青素的稳定性均有影响;Na^+、Mg^(2+)、Ca^(2+)、Zn^(2+)、Fe^(2+)、Fe^(3+)等以及柠檬酸都对桑椹花青素有增色作用;高温(50~80℃)和蔗糖对桑椹花青素的稳定性无显著影响。由于桑椹花青素的不稳定性,在其产品加工及应用中需选择或设置适合的条件提高稳定性。

Anthocyanin is a kind of natural pigment and antioxidant. But it is easily influenced by many factors,which lead to its degradation. In this study,mulberry fruit freeze-dried powder was used as material and ethanol extraction was employed to prepare anthocyanins. By taking yield of anthocyanins as evaluation index,single factor experiments were conducted. Then,Box-Behnken design and response surface methodology were implemented to optimize extraction process for anthocyanins and to analyze factors influencing stability of anthocyanins. The results showed that the optimal condition for extracting mulberry fruit anthocyanins was as follows： material liquid mass concentration 0. 073 g/m L,volume fraction of ethanol 50%,extraction solution p H 1,extraction temperature 78. 02 ℃,and extraction time 1. 5 h. Under this condition,the yield of anthocyanins from mulberry fruit freeze-dried powder reached 6. 93%. This optimized process was more economic and effective on condition that high yield of anthocyanins was maintained. The extracted anthocyanins was the most stable at p H 1. H_2O_2 damaged anthocyanins strongly,and high concentrations of Na_2S_2O_3 also reduced its stability.Ultraviolet light,outdoor natural light and indoor scattered light all had obvious effects on its stability. Na~＋,Mg^（2＋）,Ca^（2＋）,Zn^（2＋）,Fe^（2＋）,Fe^（3＋） and citric acid had hyperchromic effect on mulberry fruit anthocyanins. High temperature （ 50~80 ℃） and sucrose showed no significant effect on its stability. Because of the instability of mulberry fruit anthocyanins,favorable conditions should be selected or set up to improve its stability during production and application of anthocyanins.