籽瓜多糖的超声波辅助提取工艺、分子量和抗氧化活性研究

Study on ultrasonic extraction of seed watermelon polysaccharides and evaluation of its molecular weight and antioxidant activity

采用超声波辅助萃取技术从籽瓜中提取籽瓜多糖（SWP），在单因素实验基础上进行响应面实验，对影响籽瓜多糖得率的提取时间、提取温度和料液比三个因素进行优化，结果显示：最优工艺参数为超声时间85min、温度49℃、料液比1：1．7（g／mL），多糖得率为4．128％。采用体积排阻色谱一光散射联用测得籽瓜多糖的分子量为Mn=1．089×106g／mol。通过测定籽瓜多糖对自由基的清除率，结果显示：在浓度为0．01-0．32mg／mL对DPPH自由基的清除作用明显高于Vc，可达到68％；在浓度为5mg／mL时，对羟基（·OH）自由基的清除率达到75．35％；而对超氧阴离子（O2-·），在浓度为5mg／mL时，清除率达到50％，表明籽瓜多糖具有较强的自由基清除作用，可作为潜在天然抗氧化剂应用于食品和医药工业中。

The seed watermelon polysaccharide was extracted from seed watermelon using ultrasonic assisted extraction technique. The three factors-extraction time,extraction temperature and solid-liquid ratio were optimized based on response surface methodology（RSM）. The results showed that the optimum seed watermelon polysaccharides extraction conditions was=ultrasonic treatment time 85min,extraction temperature 49℃,and solid/liquid ratio 1 ：1.7g/mL,seed watermelon polysaccharides yield reached up to 4.128%. The molecular weight of seed watermelon polysaccharides was measured using SEC-HPLC and LLS：Mn=1.089×106g/moL. According to the scavenging capacity of seed watermelon polysaccharides against radicals,it showed that the scavenging capacity of seed watermelon polysaccharides agaist DPPH radicals was 68% at the concentration of 0.01-0.32mg/mL,higher than Vc significantly. The scavenging capacity of seed watermelon polysaccharides agaist hydroxyl radicals was 75.35% at the concentration of 5mg/mL and the scavenging capacity of superoxide radicals was 50% at the same concentration. The result showed that seed watermelon polysaccharides had strong free radical-scavenging capacity. And could be use as a potential natural antioxidant in the food and pharmaceutical industry.