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Anthocyanins are important compounds contributing to the color of red wine, which play a crucial role in the quality of red wine. Anthocyanins are biosynthesized via the phenylpropanoid-flavonoid pathway during the growth of wine grapes. In red wine, there is an equilibrium among anthocyanin species, and the color of red wine is closely related to the diverse structure and morphology of anthocyanins. However, anthocyanins are not stable and could be degraded through a series of reactions including oxidation. From a winemaking perspective, anthocyanins are extracted from grape skin into the wine by maceration, and anthocyanin concentrations and color of red wine vary with changes in fermentation conditions and the composition of red wine during fermentation. During wine aging, anthocyanins can react with other components to form new anthocyanin derivatives. The evolution of anthocyanins and these derivatives can lead to constant changes in red wine color during wine fermentation, aging and storage. So far, few systematic reviews have been carried out on the origin, coloration mechanism and reactions of anthocyanins in red wine, and their evolution during the production of red wine. Therefore, this paper aims to fill this lacuna in order to provide a theoretical basis for further investigation of anthocyanins in red wine.

With global climate warming, grape berries ripen too fast in warm growing regions especially in grape growing regions in western China, which in turn results in low acidity in grapes and ultimately will cause a great negative impact on the taste and quality of wine. Lachancea thermotolerans (LT) is a non-Saccharomyces yeast that can produce a high yield of lactic acid. The mixed inoculation of LT and Saccharomyces cerevisiae can effectively increase the acidity and reduce the pH of wine, thereby maintaining the microbial and color stability. In this paper, recent progress in the research and application of LT in wine fermentation is reviewed with respect to the basic physiological, biochemical and enological characteristics of LT. Furthermore, the influence of LT on the major metabolites, aroma and color of wine and the molecular mechanism of over-production of lactic acid by LT are reviewed. Finally, the commercial application of LT is outlined. This review is expected to provide a reference for further research on LT to promote its industrial application in wine production.

In this study, the influence of the distillation system, geographical origin, and aging time on the volatiles of brandy was investigated. An untargeted metabolomics approach was used to classify the volatile profiles of brandies based on the presence of different distillation systems and geographical origins. Through the predictive ability of PLS-DA models, it was found that higher alcohols, C13-norisopenoids, and furans could serve as key markers to discriminate between continuous stills and pot stills, and the contents of C6/C9 compounds, C13-norisoprenoids, and sesquiterpenoids were significantly affected by brandy origin. A network analysis illustrated that straight-chain fatty acid ethyl esters gradually accumulated during aging, and several higher alcohols, furfural, 5-methylfurfural, 4-ethylphenol, TDN, β-damascenone, naphthalene, styrene, and decanal were also positively correlated with aging time. This study provides effective methods for distinguishing brandies collected from different distillation systems and geographical origins and summarizes an overview of the changes in volatile compounds during the aging process. [ABSTRACT FROM AUTHOR]

This study investigated the effect of leaf removal at three stages of grape development on the phenolic and volatile profiles of Cabernet Sauvignon and Marselan grapevines for two consecutive years in the Jieshi Mountain region, an area of eastern China with high summer rainfall. The results indicated that cluster-zone leaf removal generally reduced the titratable acidity of both varieties, but did not affect the total soluble solids of grape berries. Leaf-removal treatments increased the anthocyanin and flavonol content of berries in both varieties. However, in Cabernet Sauvignon, leaf removal negatively affected the norisoprenoid compounds, with a more pronounced impact observed when the leaf removal was conducted at an early stage. This negative effect may be related to a decrease in the levels of violaxanthin and neoxanthin, potential precursors of vitisprine and β-damascenone. In contrast, the removal of leaves had no effect on the norisoprenoid aroma of Marselan grapes. [ABSTRACT FROM AUTHOR]

The influence of aging in different types of oak barrels on the aroma composition ofMerlot dry red wine was analyzed.Merlot dry red wine produced in Yanqing District (Beijing) in 2013 was aged for different lengths of time (zero, three, nine, and twelve months) in six different types of oak barrels separately, which had different oak species, geographic origins, and toasting degrees. The aroma compounds were extracted by head space-solid phase microextraction (HS-SPME) and liquid-liquid extraction (LLE) techniques and then analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that the species and origins of oak barrels mainly affected the concentrations of phenolic aldehydes and some volatile phenols, such as guaiacol, 4-methyl guaiacol, syringol, and 4-methyl syringol. The toasting degrees of oaks primarily affected furans and most of the volatile phenolics. Compared to lightly toasted barrels, moderately toasted barrels could increase the total concentration of phenolic aldehydes by at least 9 520 μg/L at the end of aging. The principal component and discriminant analyses showed that among samples processed in different types of oak barrels, aroma compounds derived from grapes and fermentation were similar, but the aroma compounds associated with aging in oak barrels could be used to discriminate the different types of oak barrels. The results of odor activity value analysis and the establishment of the simulated aroma profiles showed that the aromas of floral, caramel, nutty, chemical, toast, and smoky series were mainly influenced by the toasting degree of the oak barrels, while the aromas of the oak, smoke, and leather could be used to discriminate the different oak species and geographic origins of the oak barrels. This study can provide a theoretical basis for selecting and using oak barrels in the aging process of dry red wine. [ABSTRACT FROM AUTHOR]