响应面法优化柿渣中单宁提取工艺

【目的】利用响应面法优化柿渣中单宁的提取工艺，为柿单宁的综合开发利用提供技术支持。【方法】利用溶剂浸提法提取成熟柿渣中的单宁，采用福林酚法测定柿单宁含量，选取pH（水浸提取法）、乙醇体积分数（乙醇浸提法）、料液比、提取时间和提取温度为因素，柿单宁提取率（Y）为响应值，在单因素试验的基础上进行Box-Behnken中心组合试验设计，建立回归方程，优化柿渣中单宁的提取工艺。【结果】3种提取方法获得的柿单宁提取率排序为:碱性水浸>酸性水浸>乙醇浸提。选用碱性水浸提取法作为提取工艺，建立的回归方程为:Y=1.75-0.0424A+0.0164B+0.0118C+0.01AB+0.0015AC-0.0005BC-0.2528A2-0.0003B2-0.0179C2（A为pH，B为提取时间，C为提取温度）；3个因素对碱性水浸提取柿单宁提取率的影响排序为pH>提取时间>提取温度，两因素间的交互作用对柿单宁提取率的影响均不显著（P>0.05）。最佳提取工艺条件:pH 11、料液比1∶3、提取时间129 min、提取温度96.5℃，在此条件下获得柿单宁提取率为1.75%，与理论预测值（1.76%）接近。【结论】采用响应面法优化柿渣中单宁的提取工艺稳定、可行，具有实用价值，可在生产实际中推广。

Optimization of the extraction process of persimmon tannin from persimmon residue by response surface methodology

【Objective】 The response surface methodology(RSM) was used to optimize the extraction process of persimmon tannin in persimmon residue, providing technical support for the extraction and separation of persimmon tannin and the comprehensive development and utilization of persimmon tannin.【Method】 Solvent extraction of persimmon tannin from persimmon residue was carried out. The persimmon tannin was determined by Folin-Ciocalteu method. The pH (water extraction), volume fraction of ethanol(ethanol extraction), the material-liquid ratio, extract time, and extract temperature were selected as different experimental factors, persimmon tannin extraction rate(Y) as response value. Based on the experiment of single factor, the combined experimental design of Box-Behnken center was carried out. Establishing regression equation to optimize the extraction process of persimmon tannin from persimmon residue.【Result】 The results showed that the extraction rate of persimmon tannin:alkaline water extraction>acid water extraction>ethanol extraction.Established regression equation of alkaline water extraction was:Y=1.75-0.0424A+0.0164B+0.0118C+0.01AB+0.0015AC- 0.0005BC-0.2528A2-0.0003B2-0.0179C2(A was the pH, B was the extraction time and C was the extraction temperature). The influence order of the three factors on yield of extraction rate of persimmon tannin by alkaline water extraction was pH>extraction time>extraction temperature. The interaction between the two factors on extraction rate of persimmon tannin was not significant(P>0.05).The optimal process conditions were:pH 11, solid-liquid ratio 1:3, extraction time 129 min, extraction temperature 96.5℃, and the extraction yield was 1.75%, which was close to the theoretical prediction (1.76%).【Conclusion】 The response surface method is used to optimize the extraction process of persimmon tannin in persimmon residue, which is stable and feasible. It has practical value and can be popularized in p