麻栎橡子单宁脱除工艺优化及抗氧化性

为探索高效可行的麻栎橡子单宁脱除工艺,实现其综合开发,以桥山林区麻栎橡子为原料,采用超声辅助乙醇法对影响单宁脱除率的因素进行单因素试验,选择影响显著的4个因素进行响应面分析,并测定单宁对1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基和羟自由基(·OH)的清除率,以探索麻栎橡子单宁的抗氧化活性。结果表明,液料比、乙醇体积分数、脱除温度、超声功率对单宁脱除率影响显著,模型拟合效果显著。最优脱除工艺为液料比42∶1(mL/g)、乙醇体积分数53%、脱除温度65℃、超声功率240 W,单宁脱除率为37.27%。麻栎橡子单宁抗氧化性与其质量浓度呈线性正相关,质量浓度为80 mg/L时,其对DPPH自由基的清除率可达75.56%,对·OH的清除率可达62.74%,可作为新型抗氧化剂。

Extraction Optimization and Antioxidant Activity of Tannins from Quercus acutissima Acorns

To explore an efficient and feasible extraction procedure for the removal of tannins in Quercus acutissima acornsfor comprehensive exploitation of Quercus acutissima acorns, the factors affecting the removal rate of tannins from Quercusacutissima acorns collected from Qiaoshan Mountains by ultrasonic-assisted extraction using ethanol as extraction solventwere firstly investigated by one-factor-at-a-time method and then the significant ones were selected and further optimizedby response surface methodology. Besides, the antioxidant activity of the tannins extracted was determined by testing1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and hydroxyl radical (·OH) scavenging capacity. Our results demonstratedthat liquid-to-solid ratio, ethanol concentration, extraction temperature and ultrasonic power were found to be the factorswith a significant effect on the removal efficiency of tannins. The proposed model showed good fitness. An ethanolconcentration of 53%, a liquid-to-solid ratio of 42:1 (mL/g), an extraction temperature of 65 ℃ and an ultrasonic power of240 W were found to be optimal for maximum removal rate of tannins (37.27%). The antioxidant activity of the tanninsextracted was positively linearly correlated with their concentration, and the scavenging percentages for DPPH and hydroxylradical radicals were respectively 75.56% and 62.74% at a tannin concentration of 80 mg/L. Hence, the tannins can be used anew antioxidant.