本文阐述一种高效，环保制备高价值天然抗氧化剂根皮素的方法。以天然的柑橘提取物柚皮苷为原料，经一锅法加氢反应制得柚苷二氢查尔酮，再以α-鼠李糖苷酶（α-rhamnosidase）和纤维素酶（cellulase）高效催化水解而制得根皮素。采用单因素和正交实验对α-鼠李糖苷酶和纤维素酶酶解反应的pH、温度、酶与底物比进行优化，同时对根皮素、三叶苷、柚苷二氢查尔酮、柚苷的抗氧化性进行了研究，结果表明：α-鼠李糖苷酶（α-rhamnosidase）酶解最佳工艺为温度60 ℃、pH 4、酶与底物比为0.6:1；纤维素酶（cellulase）最佳工艺为温度45 ℃、pH 5.5、酶与底物比为0.3:1。在此工艺下根皮素的转化率为96.10%，比原工艺提高了10.53%。抗氧化性研究结果为：清除DPPH自由基能力根皮素（0.18±1.45）>三叶苷（0.3±1.63）>柚苷二氢查尔酮（0.95±1.24）>柚苷（8±1.97）,还原铁离子能力为根皮素（7.1±0.68）>三叶苷（2.51±0.75）>柚苷二氢查尔酮（2.05±0.58）>柚苷（0.11±0.92）。本方法条件温和，周期短且转化率高，易于放大生产。抗氧化性结果表明根皮素具有较高的抗氧化性。这对根皮素的放大生产及应用具有重大意义。

A highly efficient and environmentally friendly method for the preparation of high-value natural antioxidant phloretin was described in this work. Naringin dihydrochalcone was prepared from naringin which is a kind of natural citrus extract by one pot hydrogenation, and then was hydrolyzed by α-rhamnosidase and cellulase to product phloretin. The process conditions including pH, temperature and substrate to enzyme ratio of α-rhamnosidase and cellulase were optimized by single factor and orthogonal experiments. The antioxidant activity of phloretin, trilobin, naringin dihydrochalcone and naringin were also studied. The results showed that the optimum conditions of α-rhamnosidase were as follow: temperature of 60 ℃, pH of 4.0, and the substrate to enzyme ratio of 0.6:1. The optimum conditions of cellulase were as follow: temperature of 45 ℃, pH of 5.5, and the substrate to enzyme ratio of 0.3:1. Under these optimum conditions, the conversion of phloretin was 96.1%, which increased by 10.53% compared to the original method. The orders of antioxidant activity were as follows: the DPPH free radical scavenging capacity of phloretin (0.18±1.45) > trilobatin (0.3±1.63) > naringin dihydrochalcone (0.95±1.24) > naringin (8±1.97), the reduced iron ion capacity of phloretin (7.1±0.68) > trilobatin (2.51±0.75) > naringin dihydrochalcone (2.05±0.58) > naringin (0.11±0.92). The new preparation method of phloretin was mild, short-cycle, high-conversion and was easy to scale up. Phloretin produced by this method had a good antioxidant activity. This work will be helpful to the enlarge production and application of phloretin.

广东省“扬帆计划”引进创新创业团队专项资助项目（2015YT02S006）