Changes of Nutritional Components and Antioxidant Activities of Moringa oleifera Leaf Extract during Fermentation

Moringa oleifera leaf extract was extracted from Moringa oleifera leaves. It was used as fermented substrate and Lactobacillus plantarum S35 was used as a fermentation strain,the fermentation conditions were obtained with the fermentation temperature of 37℃,the fermentation time of 72 h,the inoculum size of 3%,and the change of the basic physicochemical properties (pH,soluble solids,total acid),nutrient composition (reducing sugar,flavonoids,polyphenols,organic acids) and antioxidant activity (DPPH scavenging ability,hydroxyl radical scavenging ability,superoxide anion scavenging ability) of Moringa oleifera during the fermentation process of lactic acid bacteria were determined. The results showed that pH and soluble solids decreased,and the total acid increased during the whole fermentation process. The reducing sugar was observed a decreasing trend generally with the increase of fermentation time. The contents of flavonoids and polyphenols first rise and then decreased,and reached the highest at 24 h and 32 h after fermentation,with contents of 223.11 mg/L and 106.00 mg/L,respectively. The oxalic acid was no found to be a significant change,but citric acid,succinic acid,pyruvic acid,and acetic acid continuously decreased. Lactic acid increased rapidly and then decreased slightly,and reached the highest at 40 h after fermentation,with contents of 135.43 mg/L. DPPH scavenging ability,hydroxyl radical scavenging ability and superoxide anion scavenging ability reached the highest at 32 h,8 h and 32 h,and the scavenging rates were 89%,64% and 60%,respectively. In the study,it was demonstrated that fermentation of Lactobacillus was able to enhance the contents of flavonoids and polyphenols and antioxidant activity in Moringa oleifera leaves extract.