Epidemiological evidence indicates that postprandial hyperglycemia is an independent risk factor for cardiovascular disease. Improved postprandial glycemic control is promising for decreasing morbidity and mortality of cardiovascular disease in pre-diabetic and diabetic individuals. Recently, clinical trials such as the STOP-NIDDM Trial and Voglibose Ph-3 Study demonstrated that α-glucosidase inhibitor (αGI) reduces progression to type 2 diabetes from impaired glucose tolerance. Much attention has, therefore, been focused on αGI as a preventive and therapeutic agent for type 2 diabetes and its complications. Mulberry leaves have been known to prevent diabetes in Asian countries as traditional medicine. According to a previous study, mulberry leaves have strong αGI activity and its activity is caused by 1-deoxynojirimycin (DNJ), a glucose analogue. We developed an HPLC method to accurately quantify DNJ in mulberry leaves and optimized the process to achieve a DNJ-enriched (1.5%) mulberry leaf extract. We evaluated the effect of the extract on postprandial glycemic control by oral sucrose tolerance test and by a 38-day dietary trial. A dose above 0.8g of the powder (corresponding to 12mg DNJ) per, the elevation of postprandial blood glucose and secretion of insulin were suppressed significantly. Hypoglycemia, abnormal lipid profiles, or any other adverse events were not observed during and after the study period. DNJ-enriched mulberry extract may be useful in improving postprandial glycemic control in pre-diabetic or mild diabetic individuals.

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The purpose of our study is to examine the possible postprandial blood sugar control effects of various kinds of miso (fermented soybean paste), a traditional Japanese seasoning, from the viewpoint of preventing diabetes mellitus. We examined the relationship between intake of each type of miso and postprandial blood sugar levels in a human intervention trial. Glycemic index (GI) following cooked polished rice intake, in vitro effects of miso on digestive enzyme (α-amylase and α-glucosidase) activities, and the relationship of brown color degree to the postprandial blood sugar control were examined. Based on a previous report indicating that the intake of trypsin inhibitor (TI), a component of soybean as raw material, promotes insulin secretion from pancreas, we examined TI content in miso. Some kinds of miso were suggested to reduce GI. In vitro, all kinds of miso inhibited the activities of various digestive enzymes (α-amylase, α-glucosidase and trypsin) to varied extent, and a small amount of TI was detected in the miso. Also the greater the color intensity due to the brown pigment of miso, the more strongly that trypsin was inhibited. Therefore, GI was considered to be controlled several factors. Our findings suggest that postprandial blood sugar rise can possibly be controlled to a certain extent by the intake of miso, and miso may be a food that can be used to prevent diabetes in the future

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We developed an inorganic analysis technique for differentiating the geographic origin of edible burdock between Japan and China. After digesting 60 edible burdock from each Japan and China in acid, concentrations of 23 elements (Na, Mg, Al, P, K, Ca, Sc, Mn, Fe, Co, Ni, Cu, Zn, Sr, Rb, Cd, Ba, La, Ce, Nd, Sm, Gd and Tl) were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). A linear discriminant analysis function was developed using five elements (Na, K, Ca, Ce and Tl), and the discrimination accuracy of function was 95% for both the Japanese and Chinese samples. Results of cross validation in three ways showed discrimination accuracy exceeding 93%. Therefore, this analysis shows promise for use in inspecting agricultural products. To confirm the practicality of this technique, we distributed two Japanese and two Chinese burdock samples to three laboratories in our organization for independent analysis. The geographic origin of all samples was correctly determined. Therefore, this technique might be useful for discriminating the location of origin for edible burdock between Japan and China.

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Imported pumpkins (Cucurbita maxima), mostly from New Zealand and Mexico, account for two-fifth of the pumpkins distributed in Japan. As correct labeling of geographic origin is also required for pumpkins grown in Japan, we examined techniques to determine the geographic origin of pumpkins using 113 lots : 49 from Japan, 33 from Mexico and 31 from New Zealand. From each lot, seeds were collected from 10 pumpkins and pulverized. Approximately 1-2 g of test seed material was digested with nitric acid in a microwave digestor. Twenty-three elements (Mg, P, K, Ca, V, Mn, Co, Ni, Cu, Zn, Rb, Sr, Y, Mo, Cd, Cs, Ba, La, Ce, Nd, Sm, Gd and Tl) were analyzed by ICP-AES and ICP-MS. Linear discriminant analysis (LDA) was applied to two models to discriminate the geographic origin between Japan and Mexico (J-M) and between Japan and New Zealand (J-N). Using the established J-M LDA model using 6 elements (P, Ni, Zn, Rb, Sr and Mo) on 38 samples, 89% were correctly determined. Using the established J-N LDA model with 8 elements (P, K, Ca, Ni, Zn, Rb, Sr and Ba) correctly assigned the location of 87% of 39 samples. This technique was evaluated by three laboratories.

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Sourdough bread is a fermented food made using lactic acid bacteria that has good flavor and antimicrobial activity. Here, a unique lactic acid bacteria was obtained from a sugar factory and used to make the sourdough bread. The flavor of the unique sourdough bread was compared to that of non-sourdough bread and commercially sourdough bread by HPLC, GC-MS, and sensory analysis. The antifungal activity was also compared by an inoculating test. Our findings showed that the unique sourdough bread has distinctive flavor and strong antifungal activity.

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[in Japanese]

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