The third crop of green tea leaves contains a relatively large amount of catechins, resulting in a bitter taste to the hot-water extract of its leaves. On the other hand, loquat leaves have a strong enzymatic activity that can oxidize catechins. They also contain chlorogenic acid, which accelerates the oxidation of catechins. Thus, we tried to promote the oxidative polymerization of catechins in third-crop green tea leaves by the addition of loquat leaves, and presumed that the taste of the third-crop green tea would be improved. However, the active ingredients contained in loquat leaves are difficult to extract with hot water due to the hardness of the leaves. Thus, we mixed and kneaded the third-crop green tea leaves and loquat leaves together using the tea roller of a tea manufacturing machine, which may have facilitated the elution of the components contained in loquat leaves, and may have effectively promoted the oxidation of catechins contained in the third-crop green tea. In this study, we improved the conventional method of producing black tea leaves, and developed a method for producing new high-quality mixed and fermented tea using the third crop of green tea leaves and loquat leaves, which were previously unused resources. We outline our main efforts here.

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The antihyperglycemic and antioxidant effects of flesh and peel powder, which were isolated from the pomace of Viburnum dilatatum fruit (VPFPP), were investigated in normal and diabetic mice in order to find methods of utilizing this previously unused resource and to reduce waste. There were no negative effects on the growth and plasma biochemistries of mice that were fed a 1% VPFPP-containing diet for four weeks. Normal mice fed VPFPP did not show any elevation of non-fasting plasma glucose level. However, when VPFPP was fed to KK-A^y mice, a type 2 diabetic model mouse, the mice showed a dose-dependent suppression of increasing plasma glucose and insulin levels. When sucrose was administered orally into the fasted mice, a dose-dependent suppression of elevating plasma glucose concentration was also found in the KK-A^y mice that were fed VPFPP diets. It was considered that these inhibitory effects were induced by the α-glucosidase inhibitory activity of polyphenols and the large amount of dietary fiber contained in VPFPP. Moreover, increase of plasma lipid peroxidation was suppressed by VPFPP ingestion in KK-A^y mice. These results suggested that the flesh and peel from the pomace of V. dilatatum might be a new functional material with antioxidant and antihyperglycemic potencies.

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Nucleotide sequences of a fragment of PCR product amplified by the forward pair (5′-tgcgtacgcgatatgacga-3′) and reverse primer (5′-tgatttctcacaggtctcac-3′) was determined to distinguish genetic differences within Camellia sinensis. Different nucleotide sequences of retroposon-like sequence DNA (RLS-DNA) were detected in C. sinensis, from which the identification of tea leaves from among 40 Japanese tea cultivars was possible. Commercial teas, including ten Japanese teas, six Chinese teas, three Taiwanese teas, three Myanmar teas, and two Vietnamese teas, were also used for comparison examination as different types of green teas. Nucleotide sequence comparison analysis of RLS-DNA was able to identify tea cultivars according to the nucleotide sequence polymorphisms. This included specific cultivars, such as Okumidori and Benifuki, which were identified from green tea material. It was suggested that a 491 bp fragment of RLS-DNA was the target DNA marker for specific cultivars. Nucleotide sequence polymorphisms of RLS-DNA may be used as a powerful tool to discriminate processed materials.

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We prepared CS-ALA, the α-lipoic acid (ALA) salt of chitosan, and investigated the adsorption of primary or secondary bile acid and the release of ALA in vitro. Calcium-induced alginate gel beads (Alg-Ca) containing CS-ALA were also prepared, and the usability of these beads as a vehicle for oral administration was investigated. When CS-ALA was soaked in a taurocholate solution, it released ALA and simultaneously adsorbed bile acid. The adsorbed amount of taurodeoxycholate, a secondary bile acid, was higher than that of taurocholate. These two functions were recognized in Alg-Ca containing CS-ALA irrespective of water content of the gel matrix. As all these elements can be ingested as food, Alg-Ca containing CS-ALA could serve as a useful dietary agent for the prevention of colon cancer.

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New isolates of Saccharomyces cerevisiae from natural habitats are needed in order to give new characteristics to fermented foods such as alcoholic beverages and breads. Although many attempts to isolate S. cerevisiae strains from flowers and fruits have been made in Japan, there are few successful reports. These results indicate that an efficient method of isolating S. cerevisiae should be developed. Therefore, we tried and succeeded in isolating selective strains of S. cerevisiae from flowers in Aichi prefecture by a combination of selective enrichment culturing and PCR analysis of the rDNA 5.8S-ITS region. Six strains of S. cerevisiae were successfully isolated, and their fermentation and sugar assimilation properties were determined. Fermentation and sugar assimilation profiles were identical among five isolates, but was different in one isolate. The sugar assimilation profiles of all six isolates were different from those of the S. cerevisiae K7 used in sake-brewing and the S. cerevisiae By used in bread-making. They did not produce any killer toxins against K7 and By. The mtDNA RFLP analysis of the six isolates showed a high level of polymorphism, although identical patterns were found for two isolates. PCR analysis of the Ty1 delta element revealed that both the number and the size of the amplification products differed among the six isolates, K7 and By. These results showed genetic diversity among the six S. cerevisiae isolates.

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The radical scavenging activity found in the pomace of Viburnum dilatatum fruit and the development of its useful portions, including active compounds, were investigated. Grinding and extracting treatments of pomace (VPW) showed radical scavenging activity localized in the flesh and peel, and a new technique for the separation of flesh and peel (VPFP) from pomace by grinding with a machine similar to a rice-cleaning machine was developed. The VPFP contained 60% dietary fiber. The radical scavenging activities of VPFP were found to be 3.3 times higher than those of VPW, and its powder (VPFPP) showed even higher activity than VPFP. The concentrations of chlorogenic acid and cyanidin 3-sambubioside in VPFP and VPFPP were 10 to 21 times higher than those in VPW. These results established that polyphenols, which contribute to radical scavenging activities, localized in the flesh and peel, and that powdering enhanced its extraction. Thus, a new dietary fiber- and polyphenol-rich material may have been developed using a new technique that can physically separate the flesh and peel, which has radical scavenging activity, from wasted pomace of V. dilatatum fruit.

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We investigated the production of γ-aminobutyric acid (GABA) from glutamic acid using mushroom fruiting bodies. It was found that Flammulina velutipes (Enokitake) had the highest GABA production ability among 11 mushroom varieties. The GABA content of brown Enokitake was 6% to 7% (dry powder) after reaction for 6 to 8 hours at 20°C. After a single administration of GABA-enriched Enokitake powder, a significant lowering of blood pressure was observed in spontaneously hypertensive rats (SHR), but no effects were observed in rats with normal blood pressure (WIST). Ingestion of GABA-enriched Enokitake powder (0.9 mg GABA/kg) resulted in a reduction in systolic blood pressure (SBP) by about 30 mmHg.

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An anti-peptide antibody for a 15mer peptide, including the epitope-related amino acids of the tetrameric wheat α-amylase inhibitor (AI), CM16, was prepared in order to investigate the degradation of CM16 in a reaction mixture of wheat flour, pepsin and pancreatin using immunoblotting and enzyme-linked immunosorbent assays. The antibody had a high specificity for CM16. It was found that CM16 was partially degraded by simulated gastric fluid (SGF), and the epitope of CM16 was fully degraded after a consequent reaction of simulated intestinal fluid (SIF). Monomeric and dimeric wheat α-AI were similarly degraded by SGF and SIF.

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To study the effects of water extracts of Cucurbita pepo seeds on nocturia and sleep, we conducted a clinical study with 25 elderly volunteers with nocturia (>one void/night) using tea prepared from C. pepo seeds (pepokabo-cha). This study comprised the following periods : a screening period (1 week drinking water) and treatment periods (3 weeks drinking pepokabo-cha). As a result, the mean number of nocturnal voids decreased from 2.23±0.77 during the screening period to 1.30±0.51 by the third week of the treatment period, and the number of nocturnal voids during the first week of treatment decreased significantly relative to that of the screening period (P<0.01). The urination condition (urinary flow, residual sensation, post micturition dribble) during the treatment period was better than that of the screening period. Moreover, the level of sleep satisfaction was evaluated to be better than that during the screening period. Therefore, it is considered that pepokabo-cha improves nocturia and may improve quality of sleep. Until now, many papers have reported that the oil from C. Pepo seeds, or its ethanol-extracted fraction, has dysuria-improving effects. Therefore, our discovery of the strong nocturia-improving effects of water extracts of C. pepo seeds even after the removal of the oil is novel.

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A hot-water extract of Artemisia indica var. maximowiczii, or yomogi in Japanese, was prepared and treated with chlorogenate esterase (ETY, enzyme-treated yomogi). We investigated the inhibitory effects of yomogi, ETY, and a polyphenolic fraction on the degranulation of rat basophilic leukemia RBL-2H3 cells. All three inhibited the degranulation of the cells. The polyphenolic fraction has been identified as caffeic acid by HPLC analysis. These results suggest that the degranulation inhibitory activity is most likely derived from caffeic acid.

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The shielding of radiation in the environment after the Fukushima Daiichi Nuclear Power Plant accident were examined for the detection of a low level of radioactive cesium in food samples by using a NaI(Tl) scintillation survey meter. The reduction of the environmental radiation with different thickness of lead shield was demonstrated in a laboratory in the Tsukuba City. To detect the low level of radioactive cesium (¹³⁷Cs and ¹³⁴Cs) in barley samples, the conditions in terms of the shielding and the geometry of sample and scintillation probe were designed. Under the appropriate shielding conditions, a linear correlation between the concentration of ¹³⁷Cs and ¹³⁴Cs (Bq/kg) and the net counting rate (cps) of the NaI(Tl) scintillation survey meter was confirmed.

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[in Japanese]

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