Soybean broth (SB), a by-product of miso, soy sauce and natto manufacturing, is discarded as an industrial waste. The change in the inhibitory activity of angiotensin I-converting enzyme (ACE) in the soybean steaming process was investigated to evaluate the use of SB as a functional food material. An ACE inhibitor was isolated from SB by ion-exchange and gel chromatography. The results of the chemical identification by TOF-mass, IR, and NMR spectra analysis corresponded to those of Kristensen et al. for nicotianamine. The yield of pure nicotianamine from SB was 0.037% (dry matter). In the soybean steaming process at 121°C for 30min, the ACE inhibitory activity was the same in both raw and soaked soybeans, but decreased to 30% of raw soybeans in steamed soybeans and 10% in SB. The same changes were found for the nicotianamine content as for the ACE inhibitory activity in the soybean steaming process. As the content of lipids and water-soluble high-molecular-weight proteins is low in SB, nicotianamine can be easily isolated. Therefore, SB may be a suitable source of nicotianamine.

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The chewing patterns of young and elderly people were analyzed by electromyography (EMG) and magnitude of chewing sounds during the process of eating pickles under normal conditions to examine differences in mastication by age and food characteristics. Four types of pickles were examined : takuan, pickled shallot, pickled ginger and pickled eggplant. The number of bursts and the duration of chewing were significantly higher in the elderly group compared to those in the young group. On the other hand, chewing cycle, EMG amplitude, muscle activity per chew and magnitude of chewing sound per chew were significantly higher in the young group compared to those in the elderly group. Next, chewing properties related to the differences among the pickles were investigated. Compared to pickled ginger and pickled eggplant, takuan and pickled shallot were judged to be more difficult to masticate based on their high EMG amplitudes, muscle activities per chew and magnitudes of chewing sound per chew. The time course results of muscle activity and chewing sound for takuan revealed dramatic variation in chewing throughout the course for the young group, but not for the elderly group. These findings suggest that young people adapt better to the texture of the pickles while eating.

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The relationship between taste and ingredients was examined for mentsuyu, a Japanese noodle soup. The semantic differential (SD) technique and chemical component analysis were conducted on 16 types of mentsuyu having different combinations and proportions of ingredients. The results of the SD technique showed that mentsuyu containing an increased amount of sugar or IMP substituted for dried bonito retained a good, balanced taste. The mentsuyu containing MSG substituted for kombu had a good taste similar to the control mentsuyu containing kombu. The results of multiple regression analysis between taste and chemical components of mentsuyu showed that MSG concentration affected the taste while changes in salt concentration only slightly improved it. Factor analysis resulted in three factors, complex richness, sharpness and taste of dashi and umami. The mentsuyu containing increased amount of dried bonito and prepared using dark soy sauce showed high factor scores, suggesting that these ingredients help develop a particularly complex richness and sharpness with a taste of dashi and umami. In conclusion, the development of the mentsuyu taste requires a unique balance of dried bonito, dark soy sauce and MSG.

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Recently, the adipocyte differentiation mechanism and adiponectin secretion have been attracting attention due to their relationship with diabetes and hyperlipidemia. We investigated the effects of propolis extract on differentiation of the 3T3-L1 preadipocytes. These cells were cultured in the presence of propolis extract, and then intracellular lipid droplets were stained with oil Red O to determine the amount of adiponectin produced in culture medium by ELISA. We found that the propolis extract significantly increased triglyceride content in the cells, indicating that 3T3-L1 cells differentiated to adipocytes in the presence of insulin. Furthermore, propolis extract abolished the suppressive effect on adipocyte differentiation and adiponectin secretion of TNF-α in the presence of dexamethasone, methylisobutylxanthine and insulin. In addition, assays of the ligand-activated nuclear receptor proteins showed that propolis extract has potential as a PPAR-γ activator. These results suggest the value of propolis extract as an antidiabetic diet for regulating lipid metabolism and insulin sensitivity.

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To evaluate the effect of processing conditions on the hardness of natto, physical properties of steamed soybeans and fermented soybeans (natto) were investigated by instrumental rheological analysis and sensory evaluation. The boron content in the elution of steamed soybeans was also determined as boron is a potential indicator of cell wall fracturing, which is induced by steaming and may affect hardness reduction. The elastic modulus (E) and the storage elastic modulus (E′) of soaked soybeans significantly decreased with increasing steaming temperature, independent of the soybean variety. The sensory-evaluated hardness negatively correlated with both E (-0.75) and E′ (-0.67). On the basis of this correlation, natto with E> 200 kPa or with E′>800kPa was determined to be ‘hard’. To prevent the production of ‘hard’ natto, the optimal processing conditions were determined to be as follows : steam soybeans containing more than 80% water content at a minimum steaming temperature of 121°C for at least 15min. Increases in water content and steaming temperature were accompanied by elevation in boron elution and therefore acceleration in the rate of cell-wall fracturing due to steaming. Except for steamed soybeans with E>300kPa, there was also a negative correlation between the elution level and E, confirming that boron content positively correlates with cell wall fracturing.

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Japanese mugwort (yomogi, Artemisia princeps Pampan) has traditionally been used as a food or medicinal plant. In this study, we prepared yomogi extract to investigate its effect on lipid metabolism in stroke-prone spontaneously hypertensive rats (SHRSP) fed a cholesterol diet. The experimental diet was prepared by adding 0.3% yomogi extract to the control diet. Seven-week-old male SHRSP were fed the control or experimental diet for 35 days. In serum lipids, triglyceride concentration was significantly decreased in the experimental group, which was accompanied by a significant decrease in triglyceride content in the VLDL and LDL fractions. In addition, apoA-I was significantly increased, whereas apoB was significantly decreased in the experimental group. In the liver, there was no significant difference in the lipid content. In conclusion, ingestion of yomogi extract produces a hypolipidemic effect, which may be due to a decrease in hepatic secretion and/or synthesis of VLDL in SHRSP fed a cholesterol diet.

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The dietary effects of Chinese yam, nagaimo (Dioscorea opposita Thunb.), on 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) formation in the large intestine of mice were investigated and compared with those of other potato species. Potato consumption was found to significantly suppress ACF formation in the large intestines of all mice treated with DMH. Suppression of ACF formation was most remarkable in the nagaimo group. Moreover, the commercial product (aojiru) containing nagaimo powder also suppressed ACF formation.

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[in Japanese]

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