In order to clarify the effects of water activity (a_W) and nisin on the growth of Listeria monocytogenes in raw ham, an unheated meat product, L. monocytogenes ATCC 49594 (serotype 4b, Scott A), was inoculated into raw ham and its growth was investigated in five laboratories. L. monocytogenes did not grow in raw ham with a_W of 0.93 (0.930≤a_W<0.940) in any of the laboratories during storage for 28 days at 10°C. The addition of nisin to raw ham induced a decrease in the initial number of L. monocytogenes. It is suggested that the inhibitory effect of nisin on L. monocytogenes growth is bactericidal. Growth of L. monocytogenes was observed in raw ham with a_W of 0.94 (0.940≤a_W<0.950) in two laboratories. However, the addition of nisin (12.5mg/kg) inhibited the growth of L. monocytogenes during storage for 28 days at 10°C. These results show that utilization of nisin effectively inhibits the growth of injured L. monocytogenes in raw ham produced in accordance with the Japanese Food Sanitation Law.

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We investigated the physicochemical and sensory properties of cooked rice prepared with a newly developed superheated steam rice cooking machine. Rice prepared with an ordinary electric rice cooker was used as a reference. We also stored the two types of rice at 5°C and compared them, obtaining the following results. 1) The steamed rice was whiter than the ordinary cooked rice. 2) The steamed rice did not harden or decrease in stickiness after storage as much as the ordinary cooked rice did. 3) The steamed rice maintained a higher degree of gelatinization during storage than ordinary cooked rice did. 4) After slicing and staining grains of rice with aqueous iodine solution, the steamed rice grains were purplish red, while the ordinary cooked rice grains appeared bluish purple. Steamed rice grains kept their shape for the most part, while ordinary cooked rice grains were more deformed. 5) The run-off from the steaming process was analyzed with gel permeation chromatography and it consisted almost entirely of amylose. 6) Steamed rice that had been stored at 5°C for one day was preferred in overall sensory evaluation, and it was also less retrograded. This study confirms that some amount of amylose escapes during the process of steaming rice, and as a result steamed rice shows slower retrogradation than ordinary cooked rice.

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The present study examined the effects of milk protein hydrolysates made by the enzymatic hydrolysis of milk protein during milk fermentation. Two kinds of lactic acid starter, YC-280 (Lactobacillus bulgaricus and Streptococcus thermophilus) and ABT-1 (Lactobacillus acidophilus, Streptococcus thermophilus and Bifidobacterium bifidum BB-12) were used. Fermentation time, the production of EPS, syneresis, hardness and the viability of the bacteria were measured. The effects were different between the various milk protein hydrolysates. The addition of casein hydrolysate and whey protein hydrolysate shortened the fermentation time and increased the production of EPS ; furthermore, it reduced the syneresis and hardness of milk fermented by ABT-1. However, only whey protein hydrolysates exhibited these effects when fermentation was conducted using YC-280. These results suggest that the peptides and amino acids in milk protein hydrolysates stimulate the metabolism of lactic acid bacteria and increase EPS production, thus reducing syneresis and hardness. The effects were different depending on the hydrolysate or starter culture.

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In order to utilize rice flour in food systems with high water content, rice flour was dispersed into water to prepare a rice flour suspension and emulsion. Stability of the suspension was significantly increased by heating processes in combination with homogenization processes. The improved stability was probably due to finely dispersed rice flour particles (∼10μm) and gelatinized starch granules. Since oil droplets with a size of several micrometers disperse in an aqueous phase of many real food emulsions, rice flour is expected to be utilized as a fat replacer mimicking oil droplets. Emulsions were prepared dispersing soybean oil into a rice flour suspension. The emulsion was relatively stable to oil droplet coalescence for 7 days. Starch and proteins such as 10-16kDa prolamin adsorbed to oil droplet surfaces to stabilize the emulsion. These results suggest that rice flour is expected to be utilized as a natural emulsifier in the food industry.

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Various determination methods for alginic acid have been developed for specific samples. As we were unable to directly compare the results of these methods, we developed a novel determination method. The procedure is as follows : ① extraction of dietary fiber fraction from samples ; ② selective extraction of alginic acid from the dietary fiber fraction ; and ③ colorimetric determination of alginic acid by carbazol-sulfuric acid reaction. When kelp (alginic acid content : 26.6g/100g) assessment was repeated 7 times, the intermediate precision (relative standard deviation) was 2.1%. The lower limit of determination was 0.1g/100g when using dextrin as a blank sample. Based on the present results, the trueness (mean recovery) ranged from 67.3% to 99.2% for 7 types of food.

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Mental stress recovery effects are demonstrated after the oral ingestion of γ-amino butyric acid (GABA). The contents of GABA in fruit were compared among the eight varieties of eggplant, Solanum melongena. The average content in the fruit was 24mg/100gFW, and the difference among the varieties was not large. We found that heat treatment at 60°C helped the accumulation of GABA in the fruit. Heat treatment after supplying glutamate to the fruit duplicated the contents of GABA in the fruit. We hope that the results presented here will draw the attention of consumers.

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Most of the spring wheat in Hokkaido was replaced by winter wheat after the release of the winter hardy variety ‘Hokuei’ in 1954 ; the target of wheat breeding subsequently shifted to increased yield. After the release of the winter wheat variety ‘Horoshirikomugi’, with good storage tolerance and disease resistance, in 1974, wheat production in Hokkaido increased remarkably. At the time, Hokkaido’s wheat was mostly consumed for bread-making, and millers demanded hard wheat with higher protein content. However, the higher yield of new varieties resulted in lower protein content, generating a negative reputation because of poor bread-making qualities. Therefore, we focused on Japanese ‘Udon’ noodles, which require intermediate protein content, in consultation with millers. Our aim was to develop a winter wheat with good Udon noodle-making qualities, similar to those of Australian Standard White (ASW). ‘Chihoku-komugi’, which was released in 1981, showed slightly lower amylose content and good Udon-making qualities, because the amylose content of flour is greatly associated with the texture of Udon noodles. This variety was regarded as one of the best domestic wheat varieties for Udon noodle-making ; however, its lower disease resistance, poor milling qualities, and undesirable flour color did not satisfy farmers and millers. This led us to screen breeding lines of early generations by evaluating milling qualities and flour color. As a result, a new variety, ‘Kitahonami’, with good noodle-making and milling qualities, similar to those of ASW, was developed in 2006. ‘Kitahonami’ shows excellent milling qualities and flour color, high yield, good resistance to diseases, and pre-harvest sprouting, which is satisfactory to farmers and millers. ‘Kitahonami’ is currently cultivated throughout Hokkaido.

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Several measurements and observations were performed to improve the quality of Japanese noodles made from wheat cultivated in Saitama Prefecture. First, water distribution in noodles during and after boiling was investigated using magnetic resonance imaging (MRI). Water diffusion from the surface to the core was quantitatively determined by quantifying water distribution in the noodles, using the calibration line of spin-spin relaxation time (T₂) and moisture content in gelatinized flour gels. The slope of the force-displacement curve corresponded with the changes in water distribution. It is known that water distribution is an important factor in determining the texture of boiled noodles. Then, observations of the microstructure of boiled noodles were conducted using a fluorescence microscope. The degree of starch granule swelling and the structure of the gluten network differed depending on the location within the boiled noodle. Moreover, the effects of flour type on microstructure were also observed on the noodle surface. With respect to noodle color preservation, loss of creamy/yellow color was observed in the boiled noodles made from high lutein content flour. The lipoxygenase activity remaining in the boiled noodles was thought to cause the discoloration, and the addition of antioxidant ingredients was effective in maintaining the color of boiled noodles.

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In order to encourage the participants to reconsider how to obtain and provide food assistance in the event of a large-scale natural disaster, we held a disaster prevention forum at the 59th annual conference of the Japanese Society for Food Science and Technology. We presented various meal combinations of processed food based on the concepts of the Japanese Food Guide Spinning Top, which presents information for maintaining physical well-being that can be understood without any specialized knowledge about nutrition. In addition, we introduced menus for groups in need of special assistance such as infants, the elderly and foreign residents (e.g., Muslims). We targeted participants at a disaster prevention event as a way to induce individuals to learn diet self-help techniques, in the hopes that participation in this forum raises awareness of food-related issues in disaster prevention.

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