By analyzing the sugars extracted from oak chips toasted at various temperatures (180 to 280 °C) for various durations (10 to 30 min) in a model wine, we examined how wood polysaccharides are affected by toasting. The responses induced by toasting significantly differed among the major sugars constituting the wood. The main components of wood polysaccharides—glucose, arabinose, galactose, and xylose—were analyzed, and the results showed that galactose had the highest extraction amounts at around 220 °C of toasting, xylose at around 240 °C, and glucose at around 280 °C. On the other hand, the extraction amounts decreased with longer toasting durations. These results suggest that wood polysaccharides undergo temperature-dependent depolymerization while simultaneously undergoing denaturation. In addition, these depolymerization reactions tended to shift towards lower temperatures with longer toasting durations. The results of this study elucidate the chemical changes that occur within the wood during the toasting of oak chips and highlight the importance of the relationship between toasting temperature and duration. Additionally, this study demonstrated that by using the sugars extracted from oak chips as indicators, it is possible to partially visualize the reactions that occur within oak chips during toasting.

Ethyl caffeate (EC) is a natural phenolic compound that is present in several medicinal plants used to treat inflammatory disorders. However, its anti-inflammatory mechanisms are not fully understood. Here, we report that EC inhibits aryl hydrocarbon receptor (AhR) signaling and that this is associated with its anti-allergic activity. EC inhibited AhR activation, induced by the AhR ligands FICZ and DHNA in AhR signaling-reporter cells and mouse bone marrow-derived mast cells (BMMCs), as assessed by AhR target gene expressions such as CYP1A1. EC also inhibited the FICZ-induced downregulation of AhR expression and DHNA-induced IL-6 production in BMMCs. Furthermore, the pretreatment of mice with orally administered EC inhibited DHNA-induced CYP1A1 expression in the intestine. Notably, both EC and CH-223191, a well-established AhR antagonist, inhibited IgE-mediated degranulation in BMMCs grown in a cell culture medium containing significant amounts of AhR ligands. Furthermore, oral administration of EC or CH-223191 to mice inhibited the PCA reaction associated with the suppression of constitutive CYP1A1 expression within the skin. Collectively, EC inhibited AhR signaling and AhR-mediated potentiation of mast cell activation due to the intrinsic AhR activity in both the culture medium and normal mouse skin. Given the AhR control of inflammation, these findings suggest a novel mechanism for the anti-inflammatory activity of EC.

The skins of Vitis vinifera species contain 3-glucosyl anthocyanins (3G), but some non-vinifera species, such as ‘Yama Sauvignon’ (YS), contain a large amount of 3,5-diglucosyl anthocyanins (35DG), and the behavior of anthocyanin coloration with respect to pH is quite different. The anthocyanins of YS showed a very weak color at a pH of 3 or higher but a very strong color below a pH of 3. Furthermore, when we investigated the effect of co-pigmentation in commercially available wines, we found that YS red wine contained a large amount of co-pigmented anthocyanins, and even wine aged for about 4 years contained a large amount of co-pigmented anthocyanins. Due to concerns regarding disease resistance, many hybrid varieties of V. vinifera and non-vinifera species have been bred, but it is important to take these special properties of 35DG into consideration when producing wine.

This study aimed to clarify differences in susceptibility to red wine pellicle formation by pellicle-forming yeasts between two wine grape cultivars and to investigate wine components affecting pellicle formation. Twenty wines each of Muscat Bailey A (MBA) and Merlot (MR), the major grape cultivars of Japanese red wine, were used. Pellicle formation occurred more often in MBA wines than in MR wines, and almost all MBA wine surfaces were covered with pellicle after incubation for five days. Principal component analysis revealed the relationships between pellicle formation and the concentrations of ethanol, phenolics and tannins. The mean concentration of tannins in the pellicle MR wines (436 mg/L) was significantly lower than that in the non-pellicle MR wines (660 mg/L). Furthermore, the mean concentration of tannins in MBA wines (139 mg/L) was also significantly lower than that in MR wines (570 mg/L). Wine grape cultivar having a low concentration of tannins may be highly susceptible to pellicle formation by pellicle-forming yeasts during winemaking.

This study aimed to clarify the sensory characteristics of Koshu wine, which is the most popular white wine produced in Japan, by identifying descriptive terms for sour taste, a primary aspect of wine flavor. A sensory evaluation generated 56 terms related to sour taste quality. Some terms were categorized on the basis of the timing of perception— immediately after sipping, holding in the mouth, and after swallowing—while others were classified as expressing “temporal change”, “overall impression terms”, or “metaphorical terms”. From these, 12 terms—“fresh”, “stand out”, “sharp”, “soft”, “round”, “gentle”, “bright”, “duration”, “crisp”, “intensity”, “mild”, and “calm”—were selected, with definitions and reference standards (materials or examples that represent each characteristic) established. A trained sensory panel evaluated 16 Koshu wines, revealing significant differences in all sour taste quality terms except “duration”. The evaluation of “duration” may require improvement. Correlation analysis indicated that pH was strongly associated with “sharp” sour taste immediately after sipping, while titratable acidity and pH correlated with “round” and “gentle” sour taste when the wine was held in the mouth. Total acidity was linked to the duration of sour taste. Applying the sour taste quality terms determined from this study will enable the quantification of the sour taste quality of wines.