Maturation of chum salmon (Oncorhynchus keta) leads to nuptial coloration, deterioration and a decrease in the fat content of muscle. Consequeutly, overmatured salmon has no commercial value. In this study, to find an effective use for overmatured salmon, we applied dried fish manufacturing such as dried skipjack (Katsuobushi) on these salmon. However, dried salmon (Sakebushi) manufactured according to the ordinary Katsuobushi manufacturing process had low extractive components and showed little umami. In order to increase the extractive components, a few modifications were introduced to Katsuobushi manufacturing process; the boiling process was changed to a steaming process, and mild enzymatic proteolysis was applied before the steaming process. By the modified procedure, extractive nitrogen of Sakebushi increased 2.5 times as much as that by the ordinary procedure. As compared with commercially available Katsuobushi and dried mackerel (Sababushi), extractive nitrogen of the Sakebushi was 30% and 60% higher than that of Katsuobushi and Sakebushi, respectively, and in particular, glutamic acid in Sakebushi was 12 and 4 times higher as well. But inosinic acid of the extract of Sakebushi was significantly lower than that of the others. Sensory evaluation indicated that Sakebushi had low bitterness and sufficient umami as much as Katsuobushi and Sababushi.

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Multiple physical measurements of individual cooked rice grain were carried out to make clear the relationship between components or eating quality of rice and physical properties of cooked rice, using japonica rice for general use as samples. Three kind of tests such as low compression test (compression ratio: 25%), high compression test (90%) and continuous progressive compression test (CPC test) were adopted as multiple physical measurements. The overall hardness on high compression test had a higher single correlation with amylose content than the surface hardness on low compression test. On the other hand, the Elastic limit length on CPC test indicated a correlation coefficient at 1% significant with amylose content. The estimation formulas based on physical properties of cooked rice for each test were made by multiple regression analyses to predict overall, stickiness, and softness on sensory evaluation. It was shown that the formula on low compression test gave a highest multiple correlation coefficient with predicted values of overall and stickiness on sensory evaluation for unknown samples among these three tests. Further, it was made clear that two parameters (peak -H1 and distance L3) related to stickiness of surface layer of cooked rice grain on low compression test were important as indices to evaluate stickiness of cooked japonica rice grains corresponded to sensory test by the instrumental measurement.

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An artificial neural network (NN) is a technical model of a brain neural network. Although conventional multivariate analysis is linear, NN is a nonlinear multivariate analysis. In the brain, stimulation of certain receptors forms the sense of the taste. It is believed that there are nonlinear interactions at play in the sense of taste. Because gustation comprises nonlinear interactions, it may be modelled by NN. It is hoped that NN analysis using chemical analysis data will shed light on the gustatory properties of food more accurately than usual methods. We investigated the estimation of taste for plain yogurt using NN by incorporating chemical analysis data. The accuracy of the NN model was compared with that of linear multivariate analysis using principle component regression (PCR). NN was more accurate than PCR. This result suggests that using NN the taste for plain yogurt may be evaluated without a sensory evaluation. Analysis of the NN which predicts the taste for plain yogurt shows that it is easy to explain bad taste by a single substance (eg., phenylalanine). On the other hand, it was not possible to determine substances related to good flavor. This result implies that the good flavor of plain yogurt is the complex phenomenon due to the interactions of many factors.

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We found that mushroom tyrosinase requires different electron donors in hydroxylation reaction depending on its substrates. In this paper, we investigated this differential electron donor requirement of the tyrosinase and the mechanism for it. We assumed that in hydroxylation reaction of L-tyrosine to L-DOPA by mushroom tyrosinase, the amino group in L-tyrosine is acted as an electron donor, forming- ammonia through the imino group. According to the time-course analysis of ammonia during the reaction, ammonia was increased until 5 min, then decreased in the reaction mixture containing L-tyrosine. On the other hand, when both N-acetyl L-tyrosine and phydroxyphenylpyruvic acid were used as the substrates of tyrosinase, almost no reaction occurred. LC-MS analysis after 5 min of the reaction indicated that one main component and several minor components were produced in the reaction mixture containing L-tyrosine and tyrosinase. The main component was proven to be 5, 6-dihydroxyindole, and some of the minor components were assumed to contain also some melanin intermediates combined with ammonia released from L-tyrosine by tyrosinase action. Therefore, it was deduced that amino group in L-tyrosine functioned as an electron donor, and the reaction proceeded from leuco-DOPA chrome by direct decarboxylation to 5, 6 -dihydroxyindole, then to oxidized indole-5, 6-quinone, and finally to melanin biosynthesis. Thus, we proposed the occurrence of the alternative pathway of melanin biosynthesis, also in plants, as indicated in melanogenesis of animals.

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The purpose of this investigation was to clarify the properties of antioxidative activity and antimutagenicity in vitro of proanthocyanidins (dimer and trimer) from barley bran in comparison with catechins. Radical scavenging activities to superoxide and DPPH radical of the prodelphinidins were found to be higher than those of the procyanidins, and almost the same as those of (-)-epigallocatechin ((-)-EGC) and (-)-epigallocatechin gallate ((-)-EGCG). The prodelphinidins from barley bran showed more effective antimutagenicity to MNNG and Trp-p-1 than that of the procyanidins, and showed the same or less effectiveness than those of (-)-EGCG and (-)-EGC. These results suggested that the B-rings with three hydroxyl groups (pyrogallol-type) such as prodelphinidins, (-)-EGC, and (-)-EGCG were more effective to antioxidative activity and antimutagenicity than the B-rings with two hydroxyl groups (catechol-type) such as procyanidins, (+)-catechin, (-)-epicatechin, and (-)-epicatechin gallate.

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The changes of hydration state by microwave heating were examined using various mixtures of protein powder and water from the viewpoint of the changes in physical properties and the velocity of evaporation of water, because these were remarkably different from those by conductive heating under a certain limited range of water content.
1. The bound water content of 17 kinds of commercially available protein powder were deter mined to be 0.038-0.276g of H₂O/g of dry matter by pulsed NMR method.
2. In comparison with the changes induced by conventional conductive heating, whole egg and egg albumin were more inflated, casein, gluten and soy globulin were more hardened, and gelatin was more softened by microwave heating.
3. The bound water content by pulsed NMR increased more rapidly and greatly after microwave heating, and the monolayer water contents of these samples determined with moisture sorption isotherms were much more, compared with those obtained by conductive heating.
4. In microwave heating, the water activity decreased rapidly in accordance with the proceeding of dehydration.
5. A correlation between the inflation phenomena and the changes of water states was observed. Then, a functional model was presented based on the data showing that changes in water-status were the most important factors for physical changes caused by microwave heating.

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The viscosity of O/W emulsions with each various droplet diameter was studied. Monodispersed emulsions with uniform dispersed droplets was prepared using a membrane emulsification system. The hydrophilic microporous glass membranes with the average pore diameter of 1.1, 2.9, 4.5, and 5.7μm were used to prepare O/W emulsions. Each emulsification operation was continued until the oil phase concentration of 10% (v/v). The droplet size varied depending on the average pore size and the average droplet diameter was about five times greater than the average pore diameter. In the present study, to prevent the variance of the viscosity from the droplet aggregates, the emulsion viscosity was exactly measured after stirring the emulsions before the dispersed droplets would float up. The correlation was found in the relationship between the average droplet diameter, or the totalsurface area of the droplets and the emulsion viscosity. As the dispersed droplet size decreased, the total surface area of the droplets increased. So the emulsion viscosity and the relative viscosity increased. Few studies on the viscosity of O/W emulsions with the droplet size over 5μm and the oil phase under 10% (v/v) had been reported. In the present study the correlation between the droplet size and the emulsion viscosity was statistically found on the O/W emulsions with the droplet size over 5.0μm at the oil phase concentration of 10% (v/v). And these data of the relative viscosity did not fit with the data calculated by a Mooney's equation including the factor of the droplet size.

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A finite element method (FEM) was applied to solve a heat transfer equation in the strawberry fruit, Toyonoka, assuming the modified heat transfer coefficient between strawberry fruit and cooling air at 0°C. We predicted the temperature distribution in a strawberry fruit cooled in an air flow, and obtained the relationship between the modified heat transfer coefficient and the air velocity in the range of 0.1m/s to 2.9m/s. The results revealed that, 1) predicted temperature of strawberry fruit was closely matched with observed data. The cooling rate of strawberry fruit was the smallest near the center of the maximum radius section. It is the center point of strawberry during cooling operation, 2) the following empirical equation is used to calculate the modified heat transfer coefficient between strawberry fruit and cooling air at various air velocity from 0.1m/s to 2.9m/s : h=-3.97v² +55.3v+50.0.

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