In order to examine the bioavailability of soybean isoflavone and to obtain basic nutritional data, we measured separately the quantities of each of twelve kinds of isoflavone contained in soybeans : malonyl glucosides, acetyl glucosides, glucosyl glucosides and aglycon. First, we analyzed six types of soybean generally seen in the market. Differences in total isoflavone content, some greater than 100%, were observed depending on the type of bean. Second, we analyzed the compositional changes of isoflavone, using a heating method that reflected the domestic cooking process, with soybeans of known quantities. Isoflavones were not eluted to a significant extent by immersion in water, but after boiling for 3 min, 8∼9% of the isoflavones dissolved in water, which was drained off. By boiling for 30 min and 60 min, 24% and 30%, respectively, of the total isoflavone contents in soybean broth were dissolved. Upon heating, the content of glucosyl glucosides decreased and that of malonyl glucosides increased ; this tendency became more marked as the heating time was extended. Although heating time was shorter when a pressure cooker was used, elution of isoflavone was no greater than when the broth was boiled normally. When a steamer was used for heating, only small amounts of isoflavones could be eluted.

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Dried salmon and dried cuttlefish were treated with superheated steam and hot air. The effects of both treatments in terms of surface sterilization of the products were compared, and evaluations of surface color change and product toughness were conducted. Dried salmon and dried cuttlefish had viable bacteria counts of 10⁶ or more cfu/g before treatment. The main bacterial types found were Kocuria genus and Staphylococcus genus, which are resistant to drying conditions. Treatment by hot air circulating in a dryer at 120°C and 180°C for 1min had little effect in sterilizing dried salmon, but superheated steam treatment of dried salmon using a conveyer system at 120°C for 1min or 180°C for 30s decreased viable bacteria counts to less than 300cfu/g, indicating that this treatment was more effective for sterilizing bacteria than the use of hot air. However, the toughness of the fish increased when superheated steam treatment was used. In order to minimize this effect, the superheated steam was blown from a slit to increase the efficiency of heat exchange, and the dried cuttlefish was placed on a net conveyer and passed under the superheated steam. At a temperature of 170°C or 200°C, and with a conveyor belt velocity of 5cm/s, viable bacteria on the surface of dried cuttlefish decreased less than 10⁵cfu/g, with little change in toughness or surface color. The present study demonstrated that brief treatment with superheated steam resulted in considerable reduction of surface bacteria on dried fishery products with no decrease in quality.

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The increase in serum cholesterol level in a group of rats fed a high-cholesterol diet containing an ethanol extract of Adzuki bean seeds was significantly lower than that in a group of rats fed a control diet that did not contain the extract. Feces weight and cholesterol excretion were significantly higher in the Adzuki bean group. An in vitro micellization study showed that the solubility of cholesterol micellized by addition of an ethanol extract of Adzuki bean seeds at concentrations of 1.10mg/ml∼5.56mg/ml decreased in a concentration dependent manner. In addition, liver HMG-CoA reductase activity in rats fed the Adzuki bean seed extract was significantly lower than in the control. However, there was no significant difference in the level of HMG-CoA reductase mRNA expression. Furthermore, there were no significant differences in the levels of mRNA expression of genes associated with cholesterol metabolism, cholesterol 7α-hydroxylase, LDL receptor, LCAT, ACAT, hepatic cholesterol esterase, and SREBP2. These findings suggest that an ethanol extract of Adzuki bean seeds may inhibit increases in serum cholesterol by two mechanisms : inhibition of micellization of cholesterol in the gastrointestinal tract, leading to reduced absorption of cholesterol and its excretion in feces ; and a reduction in the activity of cholesterol synthase in the liver. It is also possible that the fatty acid metabolism system was affected, because the expression of SREBP₁ was significantly lower.

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The antioxidizing effect of Adzuki polyphenol (APP) was studied in in vivo and in vitro experiments. Serum specimens and homogenates of the liver and kidney obtained from the mice which had been given a drink (20ml/d) containing 0.05% (w/v) APP for one week were less susceptible to oxidizing agents than those obtained from control mice. In particular, liver homogenates obtained from APP treated rats were significantly resistant to oxidizing agents. Increases in the serum GOT activity and production of lipid peroxides in the liver induced in response to an intraperitoneal injection of galactosamine and lipopolysaccharides were significantly suppressed in the mice which had been previously given 0.05% (w/v) APP for one week. The amounts of glutathione and GPx activity in the liver of the APP treated mice were significantly higher than those in the control mice. In view of these results, APP may have the following possible effects : it removes free radicals and reactive oxygen species produced during inflammation, it keeps both the glutathione level and the GPx activity in the body high and thereby suppresses production of lipid peroxides, and as a consequence, it suppresses aggravation of inflammation in the liver. IC₅₀ of APP for removal of DPPH radicals was 64.2μmol/l (converted as a catechin quantity), which was about half of the value of catechin and vitamin C available in the market. Moreover, 2.5ml solution of human LDL (protein concentration, 70μg/ml) containing 80μl of 0.05% APP was resistant to the oxidation-promoting action of 200μmol/l copper sulfate : Oxidation of LDL started approximately one hour later in the presence of APP than in its absence. These results suggest that APP has both an antioxidative effect and a liver protective action. It was also found in this study that the main monomer type polyphenol in Adzuki was catechin7β-glucoside.

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The results obtained in our experiment are two-fold : Firstly, a convenient model of a near-infrared spectrophotometer, which has proved to be useful in the determination of mellowness in fruit, was successfully applied to the measurement of fat content in horse mackerel and dried split horse mackerel. This measurement may be performed instantly, with the specimen remaining intact. To obtain this result, we used multiple linear regression (MLR) based on second derivative values of spectra measured at the back abdomen side part of the fish body and the fat content of the whole body. This resulted in a good calibration equation, with D2 log(1/R), at the fat band of 924nm, as the first variable. Secondly, we succeeded in developing a global calibration equation that can be used for both frozen and thawed samples of horse mackerel, eliminating the need to measure the temperature of each specimen. The global calibration equation has the function of temperature compensation, with high accuracy : 0.88 decision coefficient (R²) and 1.6% standard error of prediction (SEP) for whole fish (actual fat range 1-24%) and dried split fish (actual fat range 1-19%).

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[in Japanese]

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[in Japanese]

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