In this study, lactic acid bacteria were primarily collected from plant sources, and a bacterial library was constructed. To avoid duplicate isolates, the collected bacteria were classified by restriction enzyme cleavage polymorphism analysis of 16S rDNA. Most of the strains grew poorly in milk, with the exception of Lactococcus lactis, which showed good fermentability in milk, leading to the selection of L. lactis SIY8. Strain SIY8 exhibited a pronounced ability to induce interleukin 12. Furthermore, when strain SIY8 was cocultured with L. delbrueckii ssp. bulgaricus, the growth of the latter was promoted in the fermentation of milk. The resultant fermented milk had a higher free amino acid content than regular yogurt, potentially influencing its taste.

In this study, we compared the physiological effects of diets containing Dioscorea esculenta (Togedokoro), which is rich in diosgenin, Taro, and Jerusalem artichoke (Kikuimo) on lipid and blood glucose metabolism in KK-Ay mice, a hyperglycemic animal model. Diosgenin is known to have anti-obesity, blood glucose and lipid lowering effects. In addition, we also examined the effect of feeding KK-Ay mice diosgenin. Mice fed a diet of Togedokoro showed significantly increased total lipids and total bile acids in the feces, and significantly decreased serum total cholesterol levels. However, the significant effect on blood glucose levels observed in mice fed the Kikuimo diet was not observed in mice fed the Togedokoro diet. We speculate that this disparity may depend, in part, on the water-soluble dietary fiber content in each diet. In the diosgenin feeding experiment, diosgenin intake did not have a significant effect on glucose and lipid metabolism, but a significant increase in total lipids and total bile acids was observed in the feces. The results suggest that Togedokoro has a physiological effect on lipid metabolism, especially cholesterol metabolism, partly due to its diosgenin content. However, unlike the Kikuimo diet, the Togedokoro diet had no apparent effect on blood glucose metabolism.

This study evaluated the efficacy of food enzymes in fermented adzuki bean paste production. The optimal conditions for preparing bean pastes from rice koji flour with a particle size range of <425 μm treated with Amylase AG 300L and GODO AGI-EG as food enzymes and fermentation for 3 to 4 days at 55°C were clarified. The red and yellow colors of bean pastes were high after fermentation for 4 days compared to the color after fermentation for 3 days. The Brix% for bean pastes was significantly high, suggesting that bean pastes with a high level of sweetness could be produced using food enzymes. Textural analysis revealed that the breaking force and adhesiveness of bean pastes prepared using food enzymes were very low, indicating that bean pastes with a soft texture and low stickiness were produced. D-Glucose was a dominant saccharide in the bean pastes. Conversely, bean pastes prepared using GODO AGI-EG contained D-fructose and sucrose. A strong correlation was observed between γ-aminobutyric acid content and glutamate decarboxylase activity. Additionally, sensory analysis revealed that the food enzymes improved the color and melt-in-the-mouth feeling, as well as drastically inhibiting the koji aroma and enriching the sweetness of the bean pastes. As a result, high-quality bean pastes were produced.