提取方法对柚皮海绵层不溶性膳食纤维理化性质、功能及结构的影响

以柚皮海绵层为原料，采用酶碱法、复酶法、超声法和超声辅助复酶法提取柚皮海绵层中的不溶性膳食纤维(insoluble dietary fiber, IDF),比较4种提取方法对IDF理化以及功能性质的影响。理化指标显示，超声辅助复酶法提取的IDF的持油性和膨胀性均显著高于其他3种方法(P<0.05);酶碱法提取的IDF的持水性(12.70 g/g)和阳离子交换能力最高；扫描电子显微镜分析表明，酶碱法和超声辅助复酶法提取的IDF结构疏松多孔；此外，酶碱法提取的IDF的总酚类物质含量(2.80 mg/g)高于其他3种提取方法；超声辅助复酶法提取的黄酮类物质的含量(6.62 mg/g)高于其他3种提取方法；体外抗氧化实验表明，超声辅助复酶法和酶碱法提取的IDF具有更高的铁离子还原能力和ABTS阳离子自由基清除能力。综上所述，不同提取方法对柚皮海绵层IDF的理化指标、功能性质和抗氧化能力影响较大，超声辅助复酶法提取的IDF性质最优，可为提高柚皮海绵层利用率及进一步挖掘营养价值提供参考。

Effects of extraction methods on the physicochemical properties,function and structure of insoluble-soluble dietary fiber in sponge layer of pomelo peel

The sponge layer of pomelo peel was used as raw material to explore different extraction method on the properties of insoluble dietary fiber(IDF)extracted by enzyme alkaline method,double-enzyme method,ultrasonic method and ultrasonic-assisted double-enzymatic method.The effects of four extraction methods on physical,chemical and functional properties of IDF were compared.The physical and chemical indicators showed that the oil holding power and swelling power of ultrasonic-assisted double-enzymatic extraction of IDF were significantly higher than the other three extraction methods(P<0.05).The IDF extracted by enzymatic alkali extraction had the highest water holding capacity(12.70 g/g)and cation exchange capacity.Scanning electron microscopy analysis showed the surface of IDF extracted by enzyme alkaline and ultrasonic-assisted double-enzymatic method were loose and porous.In addition,the content of total phenolic substances(2.82 mg/g)in IDF extracted by enzymatic alkaline was higher than that of the other three extraction methods.The content of flavonoids extracted by ultrasound-assisted double enzymatic extraction(6.62 mg/g)was higher than that of the other group.The in vitro antioxidant experiments showed that IDF extracted from ultrasonic-assisted double-enzymatic method and enzyme-alkali method showed a higher iron reduction ability and ABTS free radical scavenging ability.To sum up,different extraction methods had a greater influence on the physicochemical,functional properties and antioxidant capacity of insoluble-soluble dietary fiber to sponge layer of pomelo peel.The properties of insoluble-soluble dietary fiber extracted by ultrasonic-assisted double enzymatic were superior to the other three extraction methods,which providing reference for improving the utilization rate of pomelo peel layer of sponge and further exploiting its nutritional value.