To determine the mechanism of inhibition of anthocyanin accumulation in the skin of grape berries due to high temperature, the effects of high temperature on anthocyanin composition and the responses in terms of gene transcript levels were examined using Vitis vinifera L. cv. Cabernet Sauvignon. High temperature (maximum 35 degrees C) reduced the total anthocyanin content to less than half of that in the control berries (maximum 25 degrees C). HPLC analysis showed that the concentrations of anthocyanins, with the exception of malvidin derivatives (3-glucoside, 3-acetylglucoside, and 3-p-coumaroylglucoside), decreased considerably in the berries grown under high temperature as compared with the control. However, Affymetrix Vitis GeneChip microarray analysis indicated that the anthocyanin biosynthetic genes were not strongly down-regulated at high temperature. A quantitative real time PCR analysis confirmed this finding. To demonstrate the possibility that high temperature increases anthocyanin degradation in grape skin, stable isotope-labelled tracer experiments were carried out. Softened green berries of Cabernet Sauvignon were cut and aseptically incubated on filter paper with 1 mM aqueous L-[1-(13)C]phenylalanine solution for 1 week. Thereafter, the changes in (13)C-labelled anthocyanins were examined under different temperatures (15, 25, and 35 degrees C). In the berries cultured at 35 degrees C, the content of total (13)C-labelled anthocyanins that were produced before exposure to high temperature was markedly reduced as compared with those cultured at 15 degrees C and 25 degrees C. These data suggest that the decrease in anthocyanin accumulation under high temperature results from factors such as anthocyanin degradation as well as the inhibition of mRNA transcription of the anthocyanin biosynthetic genes.

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Five aliphatic carbonyl compounds and two methoxypyrazines (MPs) were identified as olfactory dominant green odorants in macerated grape cluster stems of Vitis vinifera var. Cabernet Sauvignon and Chardonnay by a gas chromatography eluate sniffing and dilution analysis technique. Quantitative analysis of these odorants and related volatiles showed that the MP content of the stems was higher than those of the berry or leaf samples, though the aliphatic carbonyl compound content of the stems was not as high as the other parts. The addition of blended stems to the vinification process increased the MP content of the wine, but the identified aliphatic green odorants of the macerated stems were not detected in the wine. Keywords: Grape stem odorant; Cabernet Sauvignon; Chardonnay; methoxypyrazine; stemmy flavor; Vitis vinifera; wine

Proanthocyanidins, which are oligomers and polymers of flavan-3-ol units (e.g., (+)-catechin and (−)-epicatechin), are important components of grapes for red winemaking. Flavan-3-ols are biosynthesized by the catalysis of anthocyanidin reductase (ANR) and leucoanthocyanidin reductase (LAR). In this study, we investigated the effect of shading on proanthocyanidin biosynthesis in berries of Vitis vinifera 'Cabernet Sauvignon'. Shading of the berries reduced the accumulation of proanthocyanidins and the transcription of ANR and LAR genes in the skins during berry development, while no significant effect was observed in the seeds. Because the proanthocyanidins significantly decreased in the skins and seeds of the control berries during ripening, the levels of proanthocyanidins were similar in the shaded and control berries at the harvest stage.

Effect of dietary supplementation of two types of rice bran fraction on blood pressure (BP), lipid profile, and glucose metabolism in stroke-prone spontaneously hypertensive rats was studied. Male 4-week-old rats were divided into one group fed the AIN-93M-based control (C) diet and two groups fed diet supplemented with 60 g/kg of Driselase and ethanol fractions (DF and EF, respectively) of rice bran. After 8 weeks feeding, the BP decreased in the DF and EF groups in comparison with the C group (p < 0.01). Plasma ACE inhibitory activity, BUN, BUN/creatinine ratio, albumin, triglyceride, and glucose levels were lower in the DF and EF groups than in the C group (p < 0.01). Plasma nitric oxide and urinary 8-hydroxy-2'-deoxyguanosine levels were lower in the DF and EF groups than in the C group (p < 0.01). Rice bran fractions appear to have a beneficial dietary component that improves hypertension, hyperlipidemia, and hyperglycemia.

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