Since the Japanese are known for their long life span, “Japanese food” has potential for health promotion. To identify the era of Japanese food that was beneficial to health, we investigated the health enhancing effects of Japanese foods from different eras, focusing on lipid and carbohydrate metabolic systems. Based on the National Nutrition Survey, representative one-week menus of Japanese foods from 2005, 1990, 1975 and 1960 were prepared, cooked, and powderized. Each mixture of Japanese food was given to normal ICR mice and senescence-accelerated mice (SAM) P8 as a 30% mixture in standard diet for eight months. As a result, the Japanese food mixture from 1975 suppressed lipid accumulation in white adipose tissues in both mouse strains. To examine the underlying mechanisms, we conducted DNA microarray analysis of the liver, which is responsible for energetic lipid metabolism. As a result, the Japanese food mixture from 1975 promoted gene expression for high-energy expenditure in ICR mice. Additionally, the Japanese food mixture from 1975 promoted gene expression for enhanced degradation of triglycerides, suppression of fatty acid synthesis, and cholesterol catabolism in SAMP8 mice. Overall, it was suggested that components of Japanese foods from around 1975 are more effective than those of modern Japanese foods in preventing metabolic syndrome.

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Using 4 g samples of 15mm and 3.5mm agar gel cubes, the size of gel pieces generated after mastication (1∼10 times) was measured. The total number of gel pieces, which were arranged in size from large to small, was then categorized into 10 groups, and the average size in each group was calculated. Next, the correlation between the mean size of gel pieces and the number of chewing cycles was investigated. In the 15mm agar gel cube group, the size of gel pieces after mastication was widely distributed, and the gel bolus was evaluated to be more easily collected than the bolus of the 3.5mm agar gel cubes. In the 3.5mm agar gel cube group, the size distribution of gels after a small number of chewing cycles resembled a normal distribution ; however, the size distribution of the 3.5mm agar gel cubes approached that of the 15mm agar gel cubes with a larger number of chewing cycles. With respect to the rate of reduction of the average size for the number of chewing cycles in all 15mm cubic agar gel groups and in the 3.5mm cubic agar gel groups with small size pieces, it was accepted that crossover structure, i.e., two kinds of domains where inclination differs, exists. The present results using 4g samples of both 15mm and 3.5mm agar gel cubes suggested that facile bolus formation, an important factor in swallowing, is influenced by the size dispersion more than by the actual size of gel pieces that comprise the bolus. Furthermore, the results also suggest that the gel bolus is easier to gather with gel pieces of various sizes than with those of similar sizes.

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Contents of quercetin glucosides, antioxidant capacities (ORAC method), and total polyphenol contents were compared among 9 cultivars of onions harvested in Hokkaido, Japan. The contents of quercetin glucosides ranged from 31.24±2.15 to 133.7±8.88 μmol/100g fresh weight. ORAC values and total polyphenol contents ranged from 878.1±44.7 to 2 075.6±168.6 μmol Trolox equivalent/100g fresh weight, and 22.65±1.41 to 48.44±1.35mg gallic acid equivalent/100g fresh weight, respectively. “Tsukikou 24” showed the highest quercetin content, ORAC value, and total polyphenol contents. “Tsukikou 24” was the richest in quercetin derivatives among the onion cultivars ; hence, it is suggested that its extract showed the highest antioxidant capacity.

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Ground meats (3% NaCl) composed of frozen surimi of arabesque greenling (AG) or walleye pollack (WP), both with and without the addition of 3% protein powders (albumen powder (Al), soybean protein powder (Sp), and Na-caseinate (C-Na)), were heated at 90°C for 30min. both with and without preheating at 25°C for several hours. The rheological properties of the heated gels were then measured with a rheometer throughout the preheating process. The heated gels were solubilized in various solvents, including 0.6M NaCl (N), 1.5∼8.0M urea (U), and 2% mercaptoethanol (Me), and protein solubility was determined. 1) Direct heating of AG and WP and two-step heating of AG, both with and without the addition of individual protein powders, resulted in unset gels. 2) Two-step heating of WP, both with and without the addition of Al or Sp, resulted in a set gel, while the use of C-Na resulted in an unset gel. 3) The majority of the protein structure of unset gels was readily soluble in N+8.0M U+Me, whereas the solubility of set gels in N+8.0M U and N+8.0M U+Me was greatly reduced with the accumulation of an insoluble gel structure. 4) Protein solubility differed clearly between the set and unset gels. A large difference in the possible types of binding forces involved in both gel structures was therefore suggested.

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A new Bacillus subtilis natto-fermenting strain, Miyagi-4100, showing enhanced exoenzyme production and developed from the parental Miyagi-4 strain, was used to prepare natto from hard-hulled black soybeans. In this study, we evaluated the ability of Miyagi-4100 to ferment black soybeans, based on the amount of viscous substances, poly-γ-glutamic acid and levan, as well as the degree of hardness of the fermented black soybean component. Miyagino, a commercial starter strain, and Miyagi-4 were compared to Miyagi-4100. Black soybean natto produced with Miyagi-4100 contained much more levan than that produced with Miyagi-4, and showed a tendency for decreased hardness. Therefore, we conclude that Miyagi-4100 is highly applicable to fermenting black soybeans to natto.

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In the enzymatic peeling process of persimmon fruit, heat treatment prior to enzyme treatment is indispensable, as heat inactivation of polygalacturonase inhibiting protein (PGIP) greatly enhances the enzymatic degradation of pericarp tissue, and heat treatment produces cracks on the pericarp surface of certain cultivars. These cracks act as channels that introduce enzyme solution into the pericarp tissue. Since the frequency of crack formation affects the quality of peeled fruit, a combination of PGIP heat inactivation and mechanical perforation using metal needles, instead of heat-induced crack formation, has been proposed to improve the enzymatic peeling process of persimmon fruit. However, this process requires specially designed machinery to achieve uniform perforation. In the course of investigating the chemical components of the cuticle membrane of persimmon fruit, we found that the cuticle loses its stretching strength with the removal of wax, one of the main components of the cuticle membrane. Raw fruit treated with chloroform/methanol (1 : 1, v/v) to weaken the cuticle membrane before heat-treatment, showed increases in surface cracks and improved enzymatic peeling efficiency. A practical process applicable to food processing was achieved using a combination of chemical treatment in a detergent solution, for wax extraction, and heat treatment in a weak alkali solution, producing results similar to treatment with perforation. Using this new process, the entire enzymatic peeling process of persimmon fruit can be performed in solutions without mechanical perforation.

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In this study, methods for the extraction of nasunin, delphinidin-3-(p-coumaroylrutinoside)-5-glucoside, an antioxidant anthocyanin contained in eggplant peel, were investigated. Extracts were obtained by treating the peel with 0.5% acetic acid, after washing the peel 3 times in order to reduce the content of chlorogenic acid. About 80mg of nasunin (86.5% purity) was obtained as the Sep-pack C₁₈ cartridge-absorbable fraction of the extracts from 185g of peel. When the obtained nasunin was dissolved in McIlvaine buffer (pH 4.5) and incubated for 2 weeks at 4°C in the dark, its concentration was reduced to 65.1%. On the other hand, when nasunin was collected as a nasunin-casein complex from the extracts, using isoelectric point precipitation, nasunin showed enhanced stability. Using this method, 60.8% of nasunin was recovered from the extracts. After 2 weeks incubation at 4°C in the dark, no significant reduction in nasunin content was observed. Furthermore, when freeze-dried, the nasunin-casein complex was relatively stable, remaining 89.4% stable even at room temperature. From the results, it was concluded that the nasunin-casein complex can be used for effective preparation of stable nasunin-containing food material from the extract of eggplant peel.

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One hundred sixteen samples of black soybeans were collected from various areas of Japan, including Hokkaido, Honshu and Kyushu, between 2010 and 2012. Total anthocyanin and proanthocyanidin contents were determined by the pH differential and 4-dimethylaminocinnamaldehyde (DMAC) methods, respectively. Total anthocyanin content ranged from 0.25 to 1.40mg/g as cyanidin-3-glucoside equivalents, with a mean value of 0.90mg/g. Proanthocyanidin content ranged from 0.23 to 1.52mg/g as (+)-catechin equivalents, with a mean value of 0.93mg/g. A weak negative correlation was observed between black soybean weight and total proanthocyanidin content (n=116, r_s=—0.332, P<0.01), while no correlation was found between black soybean weight and total anthocyanin content (n=116, P=0.18). Total anthocyanin content of black soybean was highly positively correlated with total proanthocyanidin content (r=0.739, P<0.01).

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Citrus fruits contain a variety of functional constituents. However, in some cases, the citrus flesh lacks certain functional constituents, such as nobiletin and auraptene. During juice extraction, nobiletin is extruded from the peel of ‘Shiikuwasha’ into the juice. As a result, nobiletin becomes available in the juice. The new Citrus-Ponciruss hybrid ‘Aurastar’ contains large quantities of auraptene in both the flesh and peel. Additionally, satsuma mandarin juice, enriched with β-cryptoxanthin, was produced by supplementation with an extract of its by-product. A simple, low-cost production process for isolating β-cryptoxanthin from by-products was also developed. Development of novel products containing functional constituents is significant for farmers and agribusiness.

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Programmed citrus breeding in Japan began at the National Institute of Fruit Science in 1937. The intent was both to improve fruit quality and productivity and to broaden fruit ripening time. Citrus is a woody perennial crop that requires a lengthy period of time during cross-breeding for the cross-seedlings to flower and bear fruit. Polyembryony is a fatal obstacle specific to citrus cross-breeding in many cultivars in which a high percentage of seedlings are not hybrids, but rather identical to the female parent, which severely hinders cross-breeding. Therefore, cultivar improvement was achieved through identification of bud sports (natural mutation) among the tree branches.
On the other hand, in 1979, cross-breeding efforts slowly continued and succeeded in producing ‘Kiyomi’ tangor, which is a hybrid of ‘Miyagawa-wase’ mandarin and ‘Trovita’ orange. ‘Kiyomi’ is the first tangor cultivar to be released in Japan. It has excellent eating quality, high juiciness, and fragrant flavor. Fortunately, ‘Kiyomi’ seeds are monoembryonic, meaning that all the seedlings raised are hybrids.
In addition, since the latter half of the 1990’s, new cultivars bearing fruit containing functional constituents, including carotenoids such as β-cryptoxanthin and/or polymethoxyflavonoids such as nobiletin, have been released. ‘Kankitsu Chukanbohon Nou 6 gou’ fruit has excellent eating quality when fresh, contains high levels of functional constituents, including β-cryptoxanthin, nobiletin, tangeretin, and phenylpropanoids, and is suitable for value-added fruit processing due to its functional constituents.

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