The influence of polyphenol supplementation on ester formation during red wine alcoholic fermentation.

Pre-fermentative polyphenol supplementation in industrial scales (100-hL) and simulated fermentation (350 mL clarified juice) were conducted. Results showed that in practical winemaking, adding QCE (quercetin, caffeic acid and ellagic acid) increased acetate concentrations in wines and extra grape seed tannins (T) enhanced the effect of QCE supplementation. In simulated fermentation with clarified juice, the synergy effect of QCE and T was evidenced that ester formation was only promoted through mixed QCET supplementation. Besides, QCE supplementation benefited the formation of 4-vinylcatechol adducted malvidin-3-O-(acetyl/coumaroyl)-glucoside and decreased other anthocyanin derivatives derived from pyruvic acid and acetaldehyde, leading more pyruvic acid and acetaldehyde left in yeast to enhance the metabolic fluxes of esters. Findings manifested the connection between the formation of esters and anthocyanin derivatives during red wine alcoholic fermentation, which would be influenced by the phenolic matrix. This work could provide a perspective in winemaking industry for modulating aroma profile via polyphenol supplementation.

An effective method for the semi-preparative isolation of high-purity anthocyanin monomers from grape pomace.

Grape (Vitis vinifera L.) pomace, the residue of red wine production, is a good source material for production of anthocyanins. In this study, an effective and simple method for semi-preparative isolation of anthocyanins from grape pomace was developed. Ultrasonication with acidified MeOH was used to extract anthocyanins, with 56.15 mg total anthocyanins being obtained from 50 g grape pomace. Crude extracts were purified by XAD-7HP column chromatography, followed by isolation of the anthocyanin mixtures using semi-preparative HPLC, and subsequent identification of anthocyanin monomers by HPLC-DAD-MS/MS. Fourteen anthocyanins were isolated with high purities (≥90%), among which were non-acylated and acylated anthocyanins, and their cis and trans isomers. It is believed this is the first time that nearly all primary anthocyanin monomers in grapes have been isolated simultaneously using a single-step semi-HPLC procedure. The findings of this study will contribute to further research on anthocyanin monomers and profitable utilization of grape pomace.

Transcriptional Comparison Investigating the Influence of the Addition of Unsaturated Fatty Acids on Aroma Compounds During Alcoholic Fermentation.

The levels of unsaturated fatty acids (UFAs) in grape must significantly influence yeast metabolism and the production of aroma compounds. In this work, cDNA microarray technology was applied to analyze the transcriptional discrepancies of wine yeast (commercial wine yeast Lalvin EC1118) fermenting in synthetic grape must supplemented with different concentrations of a mixture of UFAs (including linoleic acid, oleic acid, and α-linolenic acid). The results showed that the initial addition of a high level of UFAs can significantly enrich the intracellular UFAs when compared to a low addition of UFAs and further increase the cell population and most volatiles, including higher alcohols and esters, except for several fatty acids. Microarray analyses identified that 63 genes were upregulated, and 91 genes were downregulated during the different fermentation stages. The up-regulated genes were involved in yeast growth and proliferation, stress responses and amino acid transportation, while the repressed genes were associated with lipid and sterol biosynthesis, amino acid metabolism, TCA cycle regulation, mitochondrial respiration, and stress responses. Unexpectedly, the genes directly related to the biosynthesis of volatile compounds did not vary substantially between the fermentations with the high and low UFA additions. The beneficial aromatic function of the UFAs was ascribed to the increased biomass and amino acid transportation, considering that the incorporation of the additional UFAs in yeast cells maintains high membrane fluidity and increases the ability of the cells to resist deleterious conditions. Our results highlighted the importance of UFAs in the regulation of aroma biosynthesis during wine fermentation and suggested that the improvement of the resistance of yeast to extreme stresses during alcoholic fermentation is essential to effectively modulate and improve the production of aroma compounds. A potential way to achieve this goal could be the rational increase of the UFA contents in grape must.

The content of linoleic acid in grape must influences the aromatic effect of branched-chain amino acids addition on red wine.

The effect of adding amino acids on wine aroma is largely influenced by nutritional status of grape must. In this study, the effects of linoleic acid (LA) content on the aromatic function of branched-chain amino acids (BCAAs) addition were investigated in alcoholic fermentation of Cabernet Sauvignon wine. The results showed that initial LA content in must significantly influenced the effect of BCAAs addition on volatiles in final wine. Adding BCAAs (140 mg/L of l-leucine, 117 mg/L of l-isoleucine and 118 mg/L of l-valine) in must with low LA content (12 mg/L) promoted the production of most volatiles, including higher alcohols (isobutanol, 2-phenylethanol), fatty acids (hexanoic acid, octanoic acid, decanoic acid) and esters (ethyl acetate, isoamyl acetate, 2-phenethyl acetate and ethyl octanoate), which were well consistent with previous literatures. However, this function disappeared or even became inhibition with increasing LA content in must, especially in 120 mg/L LA must, the total contents of higher alcohol, acetate esters and ethyl esters were 33.9%, 18.1% and 54.2% lower than those in the control without BCAAs addition, respectively. The transcriptional data revealed that several major genes including GAP1, ADH1, ATF1, ACC1, FAS1 and OLE1 were marked repressed by high LA content. Our data indicated that LA can regulate the expressions of related functional genes to efficiently influence the formations of volatiles in BCAAs supplemented wines. Therefore, it is essential to consider initial content of unsaturated fatty acids (LA) in must when using the strategy that supplying amino acids (BCAAs) to modulate aromatic quality of wines.

A review of polyphenolics in oak woods.

Polyphenolics, which are ubiquitous in plants, currently are among the most studied phytochemicals because of their perceptible chemical properties and antioxidant activity. Oak barrels and their alternatives, which are widely used in winemaking nowadays, contribute polyphenolics to wines and are thought to play crucial roles in the development of wines during aging. This study summarizes the detailed information of polyphenolics in oak woods and their products by examining their structures and discussing their chemical reactions during wine aging. This paper evaluates the most recent developments in polyphenolic chemistry by summarizing their extraction, separation, and their identification by the use of chromatographic and spectral techniques. In addition, this paper also introduces polyphenol bioactive ingredients in other plant foods.

Mass spectrometric and enzymatic evidence confirm the existence of anthocyanidin 3,5-O-diglucosides in cabernet sauvignon (Vitis vinifera L.) grape berries.

It has been widely accepted that anthocyanidin 3,5-O-diglucosides do not exist in Vitis vinifera L. Cabernet Sauvignon (CS) berries. However, our anthocyanin analyses using HPLC-ESI-MS/MS detected the existence of a low level of anthocyanidin 3,5-O-diglucosides in the Cabernet Sauvignon grape berries grown in China. The authenticity of these samples was confirmed with microsatellite markers. The existence of anthocyanidin 3,5-O-diglucoside was further verified by the enzymatic evidence for the first time. Four putative 5-O-glucosyltransferase (5GT) genes were isolated from the Cabernet Sauvignon berries. The enzymatic analysis showed that a recombinant protein (designated as Vv5GT3) glucosylated the 3-O- and 5-O-positions of anthocyanidins and flavonols. A phylogenetic analysis revealed that this bifunctional enzyme belongs to the 5GT subfamily of UDP-glycosyltransferases. This finding brought a new understanding of the anthocyanins' profile and their biosynthesis in V. vinifera and would be helpful for further investigations of the mechanism of accumulation of anthocyanidin diglucosides in Cabernet Sauvignon berries in China's wine-producing regions.

Influence of pre-fermentation cold maceration treatment on aroma compounds of Cabernet Sauvignon wines fermented in different industrial scale fermenters.

The influence of pre-fermentation cold maceration (CM) on Cabernet Sauvignon wines fermented in two different industrial-scale fermenters was studied. CM treatment had different effects on wine aroma depending on the types of fermenter, being more effective for automatic pumping-over tank (PO-tank) than automatic punching-down tank (PD-tank). When PO-tank was used, CM-treated wine showed a decrease in some fusel alcohols (isobutanol and isopentanol) and an increase in some esters (especially acetate esters). However, no significant changes were detected in these compounds when PD-tank was used. Ethyl 2-hexenoate and diethyl succinate were decreased, while geranylacetone was increased by the CM treatment in both fermenters. ß-Damascenone was increased by the CM treatment in PO-tank fermented wines but decreased in PD-tank fermented wines. The fruity, caramel and floral aroma series were enhanced while chemical series were decreased by the CM treatment in PO-tank fermented wines. The content of (Z)-6-nonen-1-ol in the final wines was positively correlated to CM treatment.

Phenolic profiles of Vitis davidii and Vitis quinquangularis species native to China.

The accumulation of phenolics in the skins of two Vitis davidii cultivars ('Ziqiu' and 'Xiangzhenzhu') and one Vitis quinquangularis cultivar ('Xiangshan No. 4') native to China was followed during ripening. It was found that the anthocyanin composition of all three grapes was dominated by anthocyanidin 3,5-O-diglucosides. The cultivar 'Xiangshan No. 4' (V. quinquangularis) contained a high level of 3',4'-substituted anthocyanins and low levels of flavonols and 3',4'-substituted flavan-3-ols, indicating that the F3'H branch pathway was the principal carbon pathway synthesizing mainly 3',4'-substituted anthocyanins. No myricetin-type flavonols were found in this cultivar, but in both 'Ziqiu' and 'Xiangzhenzhu' (V. davidii) cultivars the F3'5'H branch pathway was dominant, resulting in malvidin-based diglucoside anthocyanins. Cyanidin-based and petunidin-based anthocyanins were not detected in the 'Ziqiu' cultivar. Principal component analysis revealed that V. davidii grapes had abundant flavonols by the early middle developmental stages and a high level of malvidin-type anthocyanins by the late developmental stage. In contrast, the V. quinquangularis cultivar contained other anthocyanins instead of malvidin-type anthocyanins.

Important role of catalase in the production of ß-carotene by recombinant Saccharomyces cerevisiae under H2O2 stress.

The effect of H(2)O(2) supplement on cell growth and ß-carotene productions in recombinant Saccharomyces cerevisiae CFW-01 and CFW-01 ctt1 deficiency in cytosolic catalase were investigated in shaking flasks. The results showed that supplement of H(2)O(2) (0.5 and 1.0 mM) can significantly stimulate the ß-carotene production. However, ß-carotene levels of CFW-01 ctt1Δ under 0.5 and 1 mM H(2)O(2) were 16.7 and 36.7% lower than those of CFW-01, respectively. Although lacking cytosolic catalase, no significant differences in cell growth were observed between CFW-01 ctt1Δ and CFW-01 under the same level of H(2)O(2) stress. These results suggest that ß-carotene can act as an antioxidant to protect the recombinant yeast from H(2)O(2) oxidative damage in the absence of cytosolic catalase. However, catalase still plays an important role in the production of ß-carotene under H(2)O(2) stress. If catalase can not timely decompose H(2)O(2), the free radicals such as OH· derived from H(2)O(2) can result in decrease of ß-carotene concentration. Therefore, in the production of ß-carotene by H(2)O(2) stress, not only the level of oxidative stress, but also the activities of catalase in cells should be considered.

Comparison of volatile profiles of nine litchi (Litchi chinensis Sonn.) cultivars from Southern China.

Volatile components of nine litchi cultivars (10 samples) with high commercial value from Southern China were investigated by means of gas chromatography-mass spectrometry combined with headspace solid phase microextraction. A total of 96 volatiles were detected, of which 43 were identified. Seventeen common volatiles in all the samples included linalool, cis-rose oxide, alpha-terpineol, beta-citronellol, geraniol, p-cymene, ethanol, 3-methyl-3-buten-1-ol, 3-methyl-2-buten-1-ol, 1-hexanol, (E)-2-hexen-1-ol, 2-ethyl-1-hexanol, 1-octen-3-ol, 1-octanol, ethyl acetate, p,alpha-dimethylstyrene and 3-tert-butyl-4-hydroxyanisole. Although the volatile composition and concentration varied between these cultivars, the components with the highest OAVs in most cultivars were still cis-rose oxide, trans-rose oxide, 1-octen-3-ol, and geraniol. Two Huaizhi samples from two producing areas exhibited similar volatile profiles, and significantly different from other cultivars according to cluster analysis performed on amounts of major volatile components.