The changes in aroma compounds in itohiki-natto (a Japanese food made from fermented soybeans) during refrigeration were examined by the following methods because the smell was known to change under refrigeration. Itohiki-natto samples were stored in a refrigerator for a week and then aroma compounds were extracted by the simultaneous steam distillation extraction method, concentrated, analyzed by gas chromatography-olfactometry and gas chromatography-mass spectrometry. Several low-molecular-weight fatty acid esters, pyrazines, and low-molecular-weight fatty acids were detected as the main aroma compounds. After a week of refrigeration, the aroma associated with the low-molecular-weight fatty acid esters tended to weaken, the aroma associated with pyrazines and low-molecular-weight fatty acids tended to become stronger. The main aroma compounds of itohiki-natto manufactured in the laboratory were extracted by solid-phase microextraction, and analyzed by gas chromatography and gas chromatography-mass spectrometry. The aroma compounds derived from soybeans and low-molecular-weight fatty acid esters produced during fermentation decreased, and the aroma compounds derived from the pyrazines and low-molecular-weight fatty acids produced during the fermentation increased as the period of refrigeration was lengthened.

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Yacon (Smallanthus sonchifolius), a vegetable which originates from the Andean region in South America, was introduced to Japan about 20 years ago. Yacon root is known to be a good source of fructooligosaccharides (FOS). However, the effects of cooking on the FOS content in roots have not been sufficiently investigated. In this study, roots of four species of yacon (Peru-A, Sarada-Otome, Andesu-No-Yuki and Sarada-Okame) were cooked by several methods, such as boiling, microwaving, and steaming, and FOS was extracted from the treated roots and evaluated. Furthermore, the effects of peeling and grating on FOS content in the root were investigated. The following results were obtained: 1) Yacon FOS decreased markedly by storage at 4°C for 1 month, 2) FOS decreased by heating at 100°C after peeling and grating, 3) FOS in species, except for Sarada-Otome, was little influenced by treatment with 1% acetic acid for 1 hour, 4) FOS dramatically decreased with deep-frying and was little influenced by heating by methods such as boiling, microwaving, baking and steaming, and 5) Yacon extracts from Sarada-Otome containing 4% FOS had decreased emulsifying activity and increased emulsion stability. These findings suggest that high concentrations of FOS from yacon root could be obtained by using suitable cooking conditions.

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The effects of carnosine and anserine rich chicken extract on muscular power and fatigue sensation in middle and advanced age groups were investigated. Twenty middle and advanced aged healthy volunteers were divided into two groups and administered chicken extract at 1 500 mg/day (225 mg/day as carnosine + anserine) or 0 mg/day for 4 weeks. Before and after the administration period, isokinetic knee extension power, flexion power, and one-leg standing time with eyes open were assessed. Chicken extract administration significantly increased knee extension power and one-leg standing time. These results suggest that carnosine- and anserine-rich chicken extract administration effectively improves muscular power in middle and advanced age.

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In order to clarify the factors affecting the growth rate of Listeria monocytogenes in meat products, L. monocytogenes was inoculated into various meat products and raw ham, which is served unheated, and its growth rate along with the effects of pH and water activity (a_W) on the growth rate were investigated. L. monocytogenes grew in chicken nuggets and cooked pork loin ham during storage for 60 days at 10°C but did not grow in Vienna sausage which contains sorbic acid over the same period. The effect of sorbic acid on growth rate of L. monocytogenes should be investigated in more detail. On the other hand, L. monocytogenes did not grow in raw ham with pH ≤ 6.0 and a_W ≤ 0.93 during storage for 60 days at 10°C. These results suggest that the risk of listeriosis in raw ham can be reduced by adjusting pH and a_W.

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Rice flour is produced using a variety of milling techniques and has been utilized in many different types of food. Characteristics of starch have been shown to differ depending on the milling technique. However, there are few reports showing the relationship between particle diameter and various starch properties. In this study, we aimed to clarify the powder and hydration properties of rice flour. Regarding microstructures of rice flour particles, starch structure was observed in the flour produced by wet milling but not by dry milling. In the flour produced by dry milling, there were no clear relationships between particle diameter and starch properties. However, starch in rice flour produced by wet milling was damaged and crystallinity was decreased. From the hydration characteristics curve, hydration behavior was found to be especially slow in the dry milling sample with small particle diameter. In addition, the correlation between starch damage level and the hydration rate coefficient was shown. These findings indicate that hydration behavior is closely related to starch properties and that hydration rate coefficient is an important factor in utilizing rice flour in food products.

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Speck formation in wheat flour dough has been considered to be caused by tyrosinase (TyrI) from wheat. Five types (Fr. 1 to 5) of TyrI inhibitor were isolated from roasted rice bran extract (RRBE) by HPLC. Measurement of the IC₅₀ values of Fr. 1 to 5 showed that those of Fr. 2 to 5 had almost the same values, and that of Fr. 1 was much higher than that of other inhibitors. Examination of the results of inhibitory mechanisms to Tyr I for Fr. 1 to 5 were examined on Lineweaver-Burk plots, and Fr. 2 and Fr. 5 showed a competitive type, while the inhibition type of the other fractions could not be determined.

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