超声-微波预处理协同复合酶法制备壳寡糖的工艺优化及其抗氧化活性

Preparation of Chitosan Oligosaccharide by Pre-ultrasound-microwave Assisted Composite Enzymatic Method and Its Antioxidant

为了实现壳寡糖的高效制备,本研究以壳聚糖为原料,利用超声-微波预处理协同复合酶法制备低聚合度壳寡糖。以还原糖含量为指标,通过响应面设计法优化酶解工艺参数,并评估壳寡糖的抗氧化活性。结果表明:α-淀粉酶和壳聚糖酶1:1的复合酶组合效果最佳。最佳制备工艺参数为:微波功率200 W、超声功率200 W、超声-微波预处理时间5 min、底物浓度1%、pH5.8、温度53.5℃、复合酶添加量0.24%,在此条件下酶解5.7 h,还原糖含量达到最大值8.10 mg/mL。所制备的壳寡糖为2~6糖,平均分子量为993.5 Da。抗氧化活性结果表明壳寡糖具有较强的自由基清除活性,其对DPPH自由基和ABTS+自由基的IC50分别为0.274、0.127 mg/mL,铁离子还原能力在1.5 mg/mL时达到最大值24.56 mmol/L。本实验结果表明超声-微波预处理协同复合酶法在壳寡糖制备方向具有较好的应用前景。

To achieve efficient chitosan oligosaccharide preparation,chitosan oligosaccharide was prepared from chitosan through a pre-ultrasound-microwave assisted composite enzymatic method.The enzymatic hydrolysis process conditions were optimized using reducing sugar content as an indicator based on the response surface design method.In addition,the antioxidant capacity of chitosan oligosaccharide was examined.The results showed that the composite enzymes consistingα-amylase and chitosanase(1:1)possessed superior hydrolysis ability for chitosan than others.The optimum conditions of chitosan oligosaccharide preparation were as follows:A microwave power of 200 W,ultrasonic power of 200 W,5 min preultrasound-microwave time,1%substrate concentration,pH5.8,temperature at 53.5℃,0.24%composite enzyme additive amount,and 5.7 h enzymatic hydrolysis time.Under these conditions,the reducing sugar content reached the maximum(8.10 mg/mL).The prepared chitosan oligosaccharide contained 2~6 sugars with average molecular weight of 993.5 Da.The chitosan oligosaccharide had strong free radical scavenging activity,with the IC50 of DPPH and ABTS+free radicals at 0.274 and 0.127 mg/mL,respectively,as well as the ferric reducing power reached the maximum value of 24.56 mmol/L at 1.5 mg/mL.The results show that the ultrasound-microwave pretreatment combined with composite enzymatic method has a good application prospect in the preparation of chitosan oligosaccharide.