We investigated the effect of black malt vinegar on the blood pressure of spontaneously hypertensive rats (SHR). Both single (3g/kg body weight) and continuous administration (8 weeks ; 10% (w/w) of diet) of black malt vinegar showed a significant hypotensive effect compared with distilled water as a control. Wort and acetic acid, a major component of vinegar, also lowered the blood pressure of SHR. A neutralized black malt vinegar inhibited angiotensin I-converting enzyme activity in vitro (IC₅₀=3.9mL/100mL). We also compared hypotensive effects of black malt vinegar and brown rice vinegar, and found that black malt vinegar had a hypotensive effect equal to or higher than that of brown rice vinegar.

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Anti-allergic effects of 16 commercial available tea extracts were examined by measuring leukotriene B₄ (LTB₄) release from rat peritoneal cells (PC). LTB₄ production is accomplished by oxidative reactions catalyzed by 5-lipoxygenase. As several kinds of tea include polyphenols that have anti-oxidative effects, we also determined the contents of total polyphenol, flavonol and tannin, and examined DPPH radical scavenging activity of the tea extracts. Guava, sweet tea (Rubus suavissimus S. Lee), rooibos, Quercus salicina, green tea, sweet tea (family unknown) and loquat contained large amount of polyphenols. Flavonol was found in guava, and tannin was found in guava and sweet tea (Rubus suavissimus S. Lee). The extracts of green tea and sweet tea (Rubus suavissimus S. Lee) almost completely inhibited LTB₄ release from PC, while extracts of ground ivy leaves, guava and Quercus salicina inhibited release by less than 50%. We also examined the correlation between LTB₄ release and DPPH radical scavenging activity and between LTB₄ release and polyphenol, flavonol, or tannin content. LTB₄ release was negatively correlated with DPPH radical scavenging activity and total polyphenol contents, and this correlation was strong among the tea extracts that suppressed LTB₄ release. These results suggest that polyphenols in tea extracts may play an important role in the suppression of LTB₄ release and may also scavenge arachidonic acid peroxyradicals in the production of LTB₄.

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Major components of avocado and their functionalities were investigated. The avocado sample used contained 5.23±0.53g of water-soluble dietary fiber and 11.3±0.71g of water-insoluble dietary fiber per 100g edible portion on a dry-matter basis. Water-insoluble dietary fiber contained hemicellulose>cellulose>pectin, in order of content, and was characterized by settling volumes in water and a high ability to adsorb food colors such as Rose Bengal. Water-soluble dietary fiber had a high ability to adsorb iron. The antioxidant activity of avocado was found in peel>seed>pulp, in order of intensity. The peel contained considerably higher amounts of polyphenols than other parts. GC-MS analysis revealed the presence of catechin, epicatechin, chlorogenic acids and other polyphenols, particularly in the peel, that could be involved in antioxidation. Avocado peel is expected to become a new functional food material with health benefits.

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Lipolysis induced by extracts of various citrus fruits (47 cultivars) was investigated using rat fat cells. High lipolytic activity was observed in unripe fruits. Lipolytic activity was also detected in ripe fruits ; peel or segment wall extracts from ripe fruits induced lipolysis, whereas juice sac extract did not. The lipolytic activity of segment wall extract was about 27% of that of peel extract. In peel fractions, the lipolytic activity of flavedo fraction was about 3-fold higher than that of albedo fraction. Using the Citrus genus classification of Tanaka, high lipolytic activities were observed in group V [Aurantium Tanaka ; including Natsumikan (Citrus natsudaidai Hayata) and Iyokan (Citrus iyo Hort. ex Tanaka)] and group VII [Acrumen Tanaka ; including Satsuma mandarin orange (Citrus unshiu Marc.) and Ponkan (Citrus reticulata Blanco)], while group II [Limonellus Tanaka ; including Tahiti lime (Citrus latifolia Tanaka)], group III [Citrophorum Tanaka], including lemon (Citrus limon (L.) Tanaka)] and group IV [Cephalocitrus Tanaka ; including Buntan (Citrus grandis (L.) Osbeck) and grapefruit (Citrus paradisi Macf.)] tended to have low lipolytic activity. The concentration of synephrine in unripe fruit was proportional to lipolytic activity. These results suggest that the peel and segment walls of ripe fruit, which are generated in large quantities as a waste product from the citrus juicing process, may be useful as a functional food, especially as a fat reducing material.

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The effects of position on the plant, ripening stage and water stress due to root-zone restriction on the quality and radical scavenging activity of tomato was investigated. The fresh weight of tomato fruit decreased due to root-zone restriction. Brix values and glucose, fructose and reduced ascorbic acid contents tended to increase gradually with progressive ripening stage and cluster order, and were higher in water-stressed than control fruit. The reducing sugar content of tomato pulp was greater than that of jelly, while the reduced ascorbic acid content of jelly was greater than that of pulp. Nitrogen content tended to decrease gradually with progressive ripening stage and increase with progressive cluster order, and was higher in the pulp of control than water-stressed fruit. Acidity tended to decrease gradually with progressive ripening stage. Radical scavenging activity of tomato fruit tended to increase gradually with progressive ripening stage and cluster order, was higher in jelly than pulp, and was higher in water-stressed than control fruit. In addition, the activity of a sample obtained from a market was lower than that of both control and water-stressed tomato.

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Inhibition of bacterial growth in unsalted squid liver by autolytic hydrolysis under hydrostatic pressure (AHHP) to produce seasoning was investigated. The desirable temperature for AHHP at 60MPa was in a range of 45-55°C, and hydrostatic pressure had no effect on the autolysis in a range of 60-300MPa. Squid liver was almost degraded for 24-48h under the conditions of 60MPa and 50°C. The autolysate contained taste-active amino acids, such as Glu, Asp and Ala, at high concentration. Although the Cd concentration of the autolysate decreased from 45 to 32ppm, it remained at a sufficiently high level to use the autolysate as seasoning. The removal of Cd from the autolysate must be further investigated.

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[in Japanese]

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