The oxidative degradation of cholesterol was investigated with or without fatty acids at 150-200°C.Cholesterol and cholesterol oxides were analyzed by using GC and GC-MS. Cholesterol was degraded depending on the heating temperature and period of time. However, the production of cholesterol oxides was very little compared with the degraded cholesterol. In addition, the molar ratio and molecular species of cholesterol oxides produced were independent of the heating temperature and period of time. In the presence of fatty acids, polyunsaturated fatty acids accelerated the degradation of cholesterol. Vitamin E prevented not only cholesterol, but also fatty acids from oxidative degradation. When the cytotoxicity of the oxidatively degraded mixture of cholesterol was examined by using cultured intestinal epithelial crypt cells, it was found to increase depending on the period of heating time. Vitamin C was effective for preventing cell death by the oxidatively degraded mixture of cholesterol.

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Sumo is the national sport of Japan, and Sumo wrestlers have a specific diet, special physical characteristics and do a great deal of practice for their sport. These factors may markedly affect the bones. We observed for 1 year the effects of the physical characteristics, daily diet, and physical activities of sumo wrestlers on bone mineral density (BMD) and compared their BMD with that of age-matched male students as controls. BMD values for the lumbar spine, humerus, and femur of sumo wrestlers were higher than those of the controls (p<0.001) and were markedly correlated with the physical characteristics of the sumo wrestlers. Accordingly, the most important factors for sumo wrestlers to increase BMD may be improvement of their physique and enhancement of skeletal muscle strength. Sumo wrestlers 1-2 years after entering a stable showed increased BMD of the diaphysis of the humerus and femur, suggesting that the diaphysis is affected by weight and practice (load and mechanical stress). In sumo wrestlers with 6-8 years of experience, BMD of the femur proximal metaphysis was increased. This finding suggests that stamping in the ring, an exercise specific to sumo, increases BMD in each bone part

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The substances for inhibiting blood platelet aggregation were screened in the water-soluble fraction of mushrooms cultivated on a sawdust base. Oyster fungus (Pleurotus ostreatus) was especially strong in blocking the aggregation of human platelets (220×10⁶/ml) caused by ADP, collagen or thrombin, the IC₅₀ being calculated as about 11.6-27.1, μg/ml in dry weight. It was a dark yellow solution and maintained more than 90% of its anti-platelet aggregation activity after boiling at 100°C for 1 h. The active substances that were extracted and freeze-dried from oyster fungus inhibited platelet aggregation in both rats (i.p.) and humans (oral). The acceleration of plasma fibrinolysis due to the release of tissue plasminogen activator (t-PA) was also confirmed in humans. Since this substance was heat-resistant and can be mass-produced, it is expected that the material can be developed and practically applied as a functional food for preventing several thrombotic diseases.

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Dental caries are initiated by water-insoluble glucan (IG) synthesis from sucrose by glucosyltransferase that is produced by mutans streptococci such as Streptococcus mutans and S. sobrinus. An IG synthesis inhibitor purified from dark beer by ethanol precipitation and DEAE-Toyopearl chromatography showed invertase activity. As invertase hydrolyzed sucrose into glucose and fructose, dark beer showed inhibitory activity against IG synthesis and the adherence of S. sobrinus to glass surfaces (a model of the surface of a tooth). Dark beer contained more invertase and more strongly inhibited IG synthesis than pale beer. The invertase in dark beer was derived from brewing yeast.

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The pH value, taste quality and quantity of inorganic ions, free amino acids, and IMP in a hot-water extract of yellowtail muscle were compared with those of an ethanol-treated hot-water extract. A sensory evaluation revealed that the taste quality of the white muscle extract was reduced by the ethanol treatment due to enhanced sourness and a concomitant decrease in the whole-taste quality. In contrast, although the dark muscle extract also had increased sourness, this improved the whole-taste quality. Ultrafiltration to remove high-molecular-weight components in the hot-water extract failed to produce any change in pH value. There was a considerable decrease in the amounts of PO₄^3- and Mg²⁺ together with the pH value in the ethanol-treated hot-water extract, suggesting that the decrease in amount of these inorganic ions caused the pH decline in the extract. Little change in the level of free amino acids was detected after the ethanol treatment, while a reduced level of IMP, a well-known taste-active component, was found.

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The nutritional characteristics of a semi-fermented fish product, commonly known as chapa shutki in Bangladesh, were studied. Its crude protein, crude fat, and crude ash contents were 33.2, 17.0 and 12.2 %, respectively. The calcium, phosphorus, magnesium and iron contents of chapa shutki were higher than those of similar kinds of Japanese processed fish. The amino acid score of the protein was found to be 100, based on the provisional amino acid scoring pattern (FAO/WHO 1990). The percentage of available lysine was 97.6. Chemical changes in the amino acid residues scarcely occurred during processing. Palmitic, palmitoleic, stearic, oleic, linoleic, and linolenic acids were the major fatty acids of chapa shutki. Highly unsaturated fatty acids with 20 or more carbons were relatively low. No significant losses of unsaturated fatty acids were observed during the semi-fermentation process. An investigation of the extent of lipid oxidation showed that the carbonyl value and thiobarbituric acid-reactive substances value were 27 meq/kg of oil and 38 mg/kg of oil, respectively. The level of peroxidation was the very minimum. These feature indicite that chapa shutki can be considered a high-quality protein food.

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Separation, which occurred by heating to 90°C a white sauce made with a chicken thigh meat extract, was almost completely suppressed by the addition of 2.4 mM N-ethylmaleimide (NEM) or 10 mm ethylendiaminetetraacetic acid (EDTA). The proteins in the extract were not apparent in the cream layer of the white sauce from either the heated or unheated extract, and sauce separation by reheating did not occur in the white sauce containing the heated extract. These results suggest that sauce separation depended on entrapping casein micelles and oil droplets during the formation of a protein network in the extract through disulfide bonds and the interaction of divalent cations. Upon heating, the increase in surface hydrophobicity of the proteins in the extract was not affected by the presence of NEM, indicating that the degree of protein aggregation in the extract with and without NEM was similar.

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In this paper, the effect of ultra violet (UV) light irradiation on the stress-strain curve for nylon 6 fibers, treated with a disperse dye and control reference was investigated. The breaking point of the specimen irradiated by UV light was moving toward a lower extension side, depending on the exposure time, while the stress-strain curve kept the basic form of the unirradiated specimen. This phenomenon suggested an assumption that a region with a higher cohesive energy in the amorphous region is more easily damaged than a region with a lower cohesive energy. Until around 20 h UV light exposure, the breaking stress decreased in the order of untreated, controlled and dyed specimen. When the exposure time was more than 20 h, the order of retention values of dyed and controlled specimen was reversed. The results also support the assumption mentioned above.

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The leavening ability of bakers' yeast cells grown in several media containing NaCl was evaluated in several types of dough. Three types of growth media were used : YPG medium containing 5% glucose, 1% peptone, 0.5% yeast extract, 0.1% KH₂PO₄ and 0.1% MgSO₄·7H₂O (pH 5.6); YPS medium containing 2% sucrose, 4% peptone, 2% yeast extract, 0.2% KH₂PO₄ and 0.1% MgSO₄.7H₂O (pH 5.6); and MO medium containing 1% urea, 0.2% KH₂PO₄, and 5% total sugar as cane molasses (pH 5.6). The addition of 3% NaCl to each of these growth media clearly suppressed the growth of the yeast cells, irrespective of the types of media; the cell yield was decreased by 15-60% in the stationary phase. When we analyzed the leavening ability of these cells that had been exposed to salt stress, the cells showed higher leavening ability than those grown in the absence of NaCl, irrespective of the types of growth media and dough. The increase ratio of leavening ability in the presence of NaCl was highest at 45% when we used the YPS or YPG medium containing 3% NaCl and dough supplemented with 5% glucose. However, the increase was at a much lower level (2-7%) in sugar-less dough, irrespective of the types of growth media. Since the leavening ability of yeast is well known to be primarily limited by the rate of sugar uptake, the high leavening ability of bakers' yeast grown in the presence of NaCl may be due to an increase in sugar-uptake rate. The presence of NaCl in each growth medium also enhanced the leavening ability of various Saccharomyces yeast strains.

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We measured oxygen consumption (VO₂) and heart rate (HR) of university students under free-living conditions to investigate a simple and precise method for estimating energy expenditure during low-intensity daily activities. A portable telemetry system was used so that we could measure their continuous VO₂ and HR values. The measurement of VO₂ and HR in daily activities started at about 11 : 00 a.m. and ended at 7 : 00 p.m. We obtained a regression line (L3) based on the correlation between VO₂ and HR during low-intensity daily activities and estimated total energy expenditure (TEE), comparing it with TEE estimated by two other regression lines : L1 was based on the correlation between VO₂ and HR while lying down, sitting at rest and standing, and L2 was based on the correlation between VO₂ and HR during a high-intensity step exercise. The daily activities of each subject were recorded every minute, and an accelerometer was placed around the waist of each subject during the experiment. Most of energy expenditure during daily activity was below 0.05 kcal/kg/min, the intensity of their daily activities being low. TEE estimated by the heart rate monitoring method (HRM3) and based on L3 was very close TEE measured by the portable telemetry system, the correlation coefficient being very high (r=0.9998). TEE values estimated by two other heart rate monitoring methods (HRM 1 and HRM2) and based on Li and L2 were significantly greater than TEE measured by the portable telemetry system, the differences being significantly greater than that by HRM3. The correlation coefficients for HRM 1 and 2 with the portable telemetry system were low compared with that for HRM3. These results suggest that the correlation between VO₂ and HR during low-intensity activities is important for estimating energy expenditure in daily life and that it will be possible to create a simple and precise method for estimating energy expenditure during daily activities by applying L3 to the heart rate monitoring method.

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