1-Deoxynojirimycin (DNJ), an alpha-glucosidase inhibitor, has been used to prevent or treat type 2 diabetes. Low amounts of DNJ are found in mulberry leaf; however, a methodology is necessary to enhance the DNJ content of mulberry leaf extract (MLE) since increasing the amounts of DNJ is required for the prevention and treatment of type 2 diabetes. In this study, the DNJ content of MLE was increased through the optimization of the conditions for MLE fermentation by Lactobacillus plantarum SG-053, using response surface methodology (RSM). By single factor testing, the optimal conditions were identified as an inoculum concentration of 1%(v/v), an MLE concentration of 3°Bx, and no agitation. Based on a Plackett-Burman design, the following factors were considered to majorly affect the DNJ content in the MLE fermentation product: the initial pH, fermentation temperature, and fermentation time. By response surface methodology, the optimal conditions for MLE fermentation was found to have an initial pH of 5.5, a fermentation temperature of 31.9oC, and a fermentation time of 34 h. Under these optimal fermentation conditions, the DNJ content in MLE increased 3.59 times, or from 23.85 to 85.54 μg/mL.

Glucansucrase is an enzyme classified as a glycoside hydrolase (GH) 70 family, which catalyzes the synthesis of various glucans and glucooligosaccharides with a low molecular weight using sucrose as a donor of D-glucopyranose and maltose as a carbohydrate acceptor. Oligosaccharides are indigestiable carbohydrate with low calories, which have various positive effects on the health of intestinal track. In this study, oligosaccharide produced from Leuconostoc lactis CCK940 was purified and its prebiotics effect was investigated. Leuconostoc lactis CCK940 which isolated from Chinese cabbage kimchi produced oligosaccharide using 5%(w/v) sucrose as a donor and 3%(w/v) maltose as an acceptor. Oligosaccharide produced was purified using Bio-gel P2 column chromatography and DPs of the resulting oligosaccharide were ranged from 3 to 7. When the prebiotics effects of freeze dried oligosaccharide were examined, 1%(w/v) of purified oligosaccharide added to carbohydrate-free MRS showed good prebiotics effects on Lactobacillus plantarum KCCM 12116, L. reuteri KCTC40417, and Bifidobacterium animalis KCCM1209.

Recently, many studies have shown that propolis has diverse health beneficial effects such as anti-cancer, anti-bacterial, anti-inflammation, and anti-oxidant activities. Water-insolubility of propolis has made it extremely difficult in manufacturing health beneficial beverages containing propolis. In this study, the solubility of propolis was dramatically improved by entrapping with beta-cyclodextrin and the prebiotics effect of water-soluble propolis on the yogurt fermentation was investigated. Lactobacillus pentosus SC60 was selected as a starter for the yogurt fermentation due to its high DPPH radical scavenging activity. Low-fat milk which was supplemented with different concentrations of propolis (0.01, 0.05, 0.1, or 0.5% (w/v)) was fermented with L. pentosus SC60 for 30 h and the viable cell number, pH, and titratable acidity were checked. The rates of decrease in pH and increase in titratable acidity of yogurt after 12 h of fermentation were the highest when 0.5% (w/v) propolis were supplemented. Meanwhile pH and titratable acidity of yogurt without propolis reached 4.54 and 0.73%, respectively, most slowly after 30 hoffer mentation when compared with other yogurts supple mented with propolis. The viable cell number of L. pentosus SC60 in yogurt with 0.5% (w/v) propolis increased with highest rate and it exceeded 9 log CFU/mL at 8 h of fermentation, but that of yogurt with no propolis was only 8.54 log CFU/mL at 30 h of fermentation. This results showed that L. pentosus SC60 grew very well in the presence of water-soluble propolis and it is proposed that propolis acts as prebiotics