Process Optimization of Soluble Antioxidant Dietary Fiber Extracted from Spongy Layer of Guanxi Honey-pomelo Peels by Ultrasonic Assisted Enzymatic Method

In this study,the optimal extraction process of soluble antioxidant dietary fiber(SADF)from sponge layer of Guanxipomelo peels was studied to realize comprehensive utilization of honey-pomelo waste and reduce resource waste.Guanxi honey-pomelo peels were selected as raw material,and the SADF from the spongy layer of the peels was extracted by ultrasonic-assistedenzymatic method. Based on the single factor experiment which investigated the influence of ultrasonic action time,solid-liquid ratio,cellulase dosage,cellulase temperature,as well as cellulase action time on both extraction yield and antioxidant activity of SADF,Box-Benhnken dual-response surface optimization experiment characterized with 3 levels and 3 factors,combined with Matlabanalysis was carried out. The optimal technological condition was determined as follows: ultrasonic pre-treatment for 30 min,solid-liquid ratio of 1∶55 g/mL(1∶53~1∶55 g/mL),cellulase dosage of 3%,cellulase action temperature of 50 ℃(48~50 ℃),cellulase action time of 90 min(The upper limit C=90 min). On this condition,the theoretical extraction yield and hydroxyl radical clearance rate of SADF from Guanxi honey-pomelo peels can reach 31.40%(25.12%~31.40%)and 66.16%(51.50%~66.16%),respectively,which showed no significant difference between the actual value(extraction yield: 32.82%±0.33%,clearance rate: 64.43%±1.88%)(P>0.05). It can be seen that the SADF of the sponge layer from pomelo peels obtained under the optimized process conditions by Box-Benhnken combined with Matlab was of better extraction yield and hydroxyl radical clearance rate,so that providing a new idea for the extraction and application of functional raw materials.