A newly developed oven system, which generates superheated steam consisting of micro-droplets of hot water (Aqua-gas) by spraying heated water into a heating chamber, was applied to the blanching of potato. It was thought that the micro-droplets would increase the heat transfer coefficient of the heating medium to the extent that they would prevent the deterioration of foods due to drying during the heating process. Blanching of the potatoes was conducted using Aqua-gas (115°C), superheated steam (115°C) and hot water (100°C). The thermal properties of the heating mediums and the qualities of the potato processed with the heating mediums were compared. Though a greater heat transfer coefficient was measured in the Aqua-gas, no significant differences were observed in temperature distributions or the progress of peroxidase inactivation among the heating media. Heat transfer simulations showed that the temperature distribution in the potatoes was only dependent upon thermal diffusivity of the potato since the heat transfer coefficients of the heating mediums were sufficient. The potatoes processed with the Aqua-gas and with the superheated steam were firmer and brighter than the potatoes processed with the hot water. In addition, weight loss of the potatoes was reduced and any Bacillus subtilis would have been sterilized by the Aqua-gas.

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We examined mushrooms for inhibitors of angiotensin I-converting enzyme (ACE). We studied 23 different mushrooms that had shown ACE inhibition by preliminary screening. Of these mushrooms, marked ACE inhibitory activity was observed in Rhodophyllus clypeatus, Lyophyllum semitale, and Pholiota adiposa. Dialysis experiments showed that in mushrooms such as R. clypeatus and L. decastes, the main ACE inhibitor was a low molecular mass molecule. Conversely, the active substances in P. lubrica and Grifola frondosa were high molecular mass molecules, and ACE inhibitors from others species were assumed to contain both elements. It was demonstrated that mushrooms had specific characteristics with respect to their ACE inhibitory substances, and that these are reflected by their taxonomic affiliation at the level of family.
We then isolated ACE inhibitor from R. clypeatus. After extraction with 70% ethanol, we obtained crystals that showed ACE inhibition and identified them to be Nicotianamine. Of the 22 other mushrooms assayed for NA content, only Ramaria botrytis was found to produce this metabolite.

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With the increase in the proportion of older people in the population, the development of foods especially suitable for this segment of the population is eagerly expected. We produced a soft, sticky variety of natto that is easy for older people to masticate and to swallow, using a bacterial strain improved by mixed culture. By screening natto bacilli for their ability to make soft Itohiki-natto, we selected the strain Bacillus subtilis (natto) KFP 897, but the stickiness of the natto produced with this strain was very weak. Using a mixed culture of KFP 897 with Micrococcus luteus IAM1056, we obtained strain KFP 89711, which produced a soft, sticky natto. At approximately 5.2 times that of KFP 897-natto, the relative viscosity of KFP 89711-natto was close to that of marketed natto. Similarly, the activity of the γ-glutamyl-transpeptidase of KFP 897 natto was approximately six times that of KFP 89711-natto. Analysis by capillary column gas chromatography detected the ten volatile substances that are responsible for the flavor of natto, showing that the flavor of KFP 89711-natto was similar to that of Japanese Itohiki-natto. Organoleptic tests were conducted on elderly subjects concerning the taste of the new soft, sticky natto at three official centers for the elderly in Chiyodaku, Tokyo. The participants viewed the new soft, sticky natto as being slightly better than their generally held opinion of natto. Consequently, the newly developed soft, sticky natto proved to be a useful food for older people.

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In this study, the relationship between the electrical properties of frying oil (relative dielectric constant and conductance) and its deterioration indicators (acid value, amounts of polymerized triacylglycerols and chromaticity) were examined, focusing on the changes in electrical properties that accompany deterioration. The samples of frying oil used in this experiment were collected from fried food processing sites (school, hospital and factory feeding centers) and were collected at closing time every day for a maximum of ten days. An LCR meter was used for measurement of the electrical properties of the oil, and the relationships between the deterioration indicators and the electrical properties of samples used for various lengths of time were examined. It was found that more deterioration in the frying oil resulted in a greater relative dielectric constant and conductance. In particular, a clear correlation between the degree of deterioration and the conductance of the frying oil was observed. In addition, the obtained gradient (dG/dT) of conductance temperature dependence of frying oil used in this experiment showed a strong correlation with all deterioration indicators (acid value, amounts of polymerized triacylglycerols and chromaticity). From the above results, it is clear that the degree of deterioration of frying oil can easily be determined based on the conductance temperature dependence.

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The gelatinization properties of 20 kinds of Indica and Japonica rice were measured by differential scanning calorimetry (DSC), the β-amylase-pullulanase method (BAP) and Fourier-transform infrared spectroscopy (FT-IR/ATR). There was a high correlation between the peak temperature for gelatinization and the apparent amylose content. The FT-IR peak at around 1000cm^-1 increased in height with increased cooking time. The absorbance at this wavenumber reflects an increase in the amount of OH groups, which are hydrated due to gelatinization of starch. There was a high correlation in the degrees of gelatinization found by the FT-IR method and the BAP method. The calibration curve obtained in this study indicates that the measurement of the degree of gelatinization of cooked rice by FT-IR at around 1000cm^-1 is an alternative to the conventional BAP method. It was also found that the hardness and stickiness of cooked rice as determined by sensory evaluation could be predicted based on the height of the FT-IR absorption peak.

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The amount of imported of dried Shiitake (Lentinula edodes) mushrooms is twice that of Japanese production, with most imports coming from China. While all domestic cultivation occurs on logs, Chinese mushrooms are cultivated chiefly on sawdust-based medium. The Japan Agricultural Standard (JAS) law requires the correct labeling for both geographic origin and whether the cultivation method used log (GENBOKU) or sawdust-based medium (KINSHYOU) of dried Shiitake mushroom. We developed a method for determining whether dried Shiitake mushrooms originate in Japan or in China by quantifying 29 elements contained in 147 training samples. A linear discriminant analysis (LDA) model calibrated with concentrations of 5 elements (P, Cu, Zn, Mo and La) from 97 GENBOKU and 50 KINSHYOU samples, assigned the correct cultivation characteristics to 60 test samples with 100% certainty. An LDA model calibrated using the concentrations of 9 elements (Li, Mg, Al, Ca, Mn, Co, Mo, Cd and Ce) from 50 Japanese GENBOKU and 47 Chinese GENBOKU samples, correctly predicted 45 test samples with 93% certainty. In addition, the LDA model for a 3-group-classification, calibrated using the concentrations of 13 elements (P, Pb, Zn, Mo, La, Li, Mg, Al, Na, Mn, Co, Mo, Cd and Ce) from 50 Japanese GENBOKU, 47 Chinese GENBOKU and 50 Chinese KINSHYOU samples, correctly predicted the origin and type of 60 test samples with 93% certainty. It was demonstrated that the assignment of geographic origin and cultivation method of dried Shiitake could be accurately authenticated by this method.

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The possibility of identification of onion (Allium cepa L.) cultivars by DNA analysis was investigated. The genetic diversity of twenty onion cultivars from Japan, New Zealand, Australia, the USA and Thailand were examined, and 19 sets of sequence-tagged site (STS) primers were designed. Discriminating bands were amplified by each set of STS primers using DNA extracted from 24 onion bulbs of each cultivar. Individual variations in DNA bands in each cultivar were shown, which caused difficulties in discrimination between cultivars in the case of two sets of STS primers which were designed from cytoplasmic DNA (chloroplastic and mitochondrial DNA). However, some individual variations were shown in each cultivar by using the other seventeen sets of STS primers which were designed based on genomic DNA. These results suggested that the identification of onion cultivars using a single onion bulb is impossible. However, because it was shown that the population of allele frequency derived from each cultivar tended to be constant, it may be possible to identify onion cultivars using a significance test to compare allele frequencies of two populations derived from multiple onion bulbs of two varieties.

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The present study undertook to further improve the identification of onion cultivars. Using nineteen sets of Sequence-Tagged Site (STS) primers designed in our previous report, the populations of allele frequency in an additional twenty-five Japanese cultivars were examined. Significance between the allele frequencies from each combination of the forty-five cultivars, including twenty reported previously, revealed that all but five cultivars could be identified, even though the total number of combinations for the forty-five cultivars was 990.
In addition, the variation in the population of allele frequencies derived for identical cultivars for two successive years was investigated using twelve domestic and foreign cultivars. The results showed that the allele frequencies were stable and there were few differences between successive years.
In addition, the variation in the population of allele frequencies derived from identical varieties between multiple cultivation areas was also investigated. This was undertaken using three cultivars that were commonly cultivated in western Japan. The results showed that there were few differences between the various cultivation areas. Furthermore, the finding that thirty-one market samples could be determined as being one of five possible onion cultivars revealed the accuracy of this technique. It was shown that the identification of individual onion cultivars was possible using this method.

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The contents of γ-aminobutyric acid (GABA) in potatoes (Solanum tuberosum L.) and in processed potato products on the market were studied. In 22 varieties of potato, the total content of free amino acids and GABA content were found to vary from 239 to 819mg/100g FW and from 16 to 61mg/100g FW, respectively. There was also a positive correlation (r=0.8048) between the total content of free amino acids and GABA content in the Ldquo;Toyoshiro” variety that is always used in processed foods. The amount of GABA accounted for about 7 to 8% of the total amount of free amino acids. From analysis of the GABA contents of food products made from potatoes, about 61mg of GABA was found in 100g FW of a product made only from potatoes, about 20mg was found in 100g FW of a product made mainly from potatoes with mixed flour, and only a few mg was found in a product containing no potato. It was thus shown that the GABA content in processed potato products increases as the potato content increases.
These results suggest that GABA can be ingested, for various purposes, by consumption of potatoes and food products made from potatoes.

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This study assessed the effect of different temperatures on the product yield of flakes derived from shaving commercial Katsuobushi (boiled and dried bonito). The Katsuobushi was shaved using a household Katsuobushi-plane. The chosen temperature was lower than the glass transition temperature (glass state), and higher than the glass transition temperature (rubber state). Also, the load and energy associated with shaving each Katsuobushi was measured and used to compare Katsuobushi processing characteristics at the glass state and rubber state.
The results showed that the product yield in the rubber state was consistently higher than for the glass state. The shaving load of rubber state Katsuobushi was lower than that associated with the glass state. The rubber state Katsuobushi was shaved with a shaving load of between eighty-five and ninety percent that of the glass state. The shaving energy for the rubber state Katsuobushi was less than that required for the glass state. Regarding specific shaving energy, which is the shaving energy necessary to get 1g of Katsuobushi flake, the energy exerted for the rubber state Katsuobushi was less than that of the glass state. The rubber state Katsuobushi was shaved using only twenty-five to forty-six percent of the energy needed for the glass state.
From these results, it was shown that rubber state Katsuobushi could be shaved more efficiently than glass state Katsuobushi. This indicates the potential for laborsaving and boosting material yield in shaving Katsuobushi on a commercial scale.

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Water absorption and softening characteristics of dried tomatoes during soaking was measured at five temperatures ranging from 30 to 70°C. The moisture content data were fitted to an exponential model in the decreasing period using a non-linear least squares method. The measured results agreed well with the empirical results. An Arrhenius type equation was used to relate the constant k for water absorption rate to temperature. A first-order rate equation was applied to the change of surface softening for the sample during soaking. As a result, an Arrhenius relationship can be derived between the constant k_s for softening rate and water temperature. The activation energy for softening was estimated and the relationship between softening and pectin diffusion were described. Therefore, it was found that changes in surface softening associated with water absorption during soaking affect the water absorption characteristics of dried tomato material.

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[in Japanese]

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