Extensive and objective wine color classification with chromatic database and mathematical models

<p>Theoretic conjecture and mathematical models used for classifying wines into different chromatic levels were examined, based on a comprehensive chromatic database of 237 dry red wines. Similar mathematical models were also built for 79 Chinese Cabernet Sauvignon dry red wines from different regions and vintages, which could be set as chromatic reference for other Chinese Cabernet Sauvignon dry red wines. The reliability of these models and relationships between different chromatic parameters were further validated by statistical tools. Such methodology can be adopted to build chromatic references for wines from different backgrounds, thus to classify wine color more extensively and objectively.</p

Table1.DOCX

<p>The use of selected Saccharomyces and non-Saccharomyces strains as mixed starters has advantages over pure fermentation due to achieving wine products with distinctive and diversified aroma expected by consumers. To obtain a way to improve the aroma diversity and increase the differentiation of wine product, in this study, the aromatic effect of multi-culture of indigenous Torulaspora delbrueckii (TD12), simultaneous and sequential inoculation with two Saccharomyces strains (indigenous icewine yeast SC45 and commercial yeast BDX) with different enological characteristics were investigated in laboratory-scale 20 L fermenter, respectively. The results showed that T. delbrueckii co-fermented with different S. cerevisiae strain could generate diversified physicochemical and aromatic quality of wine as evidenced by PCA. Mixed fermentation of SC45/TD12 produced higher contents of higher alcohol (3-methyl-1-pentanol and phenylethyl alcohol), ethyl esters (ethyl decanoate and ethyl butanoate), terpenes and phenylacetaldehyde with less fatty acids (hexanoic acid, octanoic acid) and acetic acid, while BDX/TD12 generated more C₆ alcohol (1-hexanol) and acetate esters (ethyl acetate and isoamyl acetate). Compared to simultaneous inoculation, sequential inoculation could achieve higher aroma diversity, and generate higher intensity of fruity, flowery and sweet attributes of wine as assessed by calculating the odor activity values. The different S. cerevisiae strain and inoculation method in alcoholic fermentation could further influence the formations of aromatic compounds in malolactic fermentation. Our results highlighted the importance of S. cerevisiae strain in shaping the aromatic quality of wine in mixed fermentation, and also suggested that using different S. cerevisiae strains with distinct aromatic characteristics co-fermentation with specific non-Saccharomyces strain is a potential way to increase the aromatic diversity and quality of wine product, which could provide an alternative way to meet the requirement of wine consumers for diversified aromatic quality.</p

Comparison of phenolic and chromatic characteristics of dry red wines made from native Chinese grape species and <i>vitis vinifera</i>

<p>The phenolic and chromatic characteristics of dry red wines made from native Chinese species (<i>Vitis amurensis</i> and its hybrids, and <i>V. davidii</i>) and <i>V. vinifera</i> were evaluated by high-performance liquid chromatography/triple-quadrupole tandem mass spectrometry and spectrophotometer, respectively. <i>V. amurensis</i> and its hybrids wines had higher phenolic percentage of non-coumaroylated 3, 5-<i>O</i>-diglucosidic anthocyanins, <i>V. davidii</i> wines had higher phenolic percentage of coumaroylated 3, 5-<i>O</i>-diglucosidic anthocyanins, kaempferol-3-<i>O</i>-glucoside, and quercetin-3-<i>O</i>-rhamnoside, <i>V. vinifera</i> wines had higher phenolic percentage offlavan-3-ols and 3-<i>O</i>-monoglucosidic anthocyanins. Wines of native Chinese species had relatively higher blue % value and lower red % value. By the use of principal component analysis and Pearson correlation analysis, specific phenolic compounds could be recognized as phenolic fingerprints of different wines, which not only play an important role in wine differentiation, but also explain their chromatic differences.</p

Volatile composition and aromatic attributes of wine made with <i>Vitisvinifera L</i>.cv Cabernet Sauvignon grapes in the Xinjiang region of China: effect of different commercial yeasts

<p>The Xinjiang region is a major grape- and wine-production area in China, but the region’s notably high temperatures in the summer and year-round intense sun exposure play negative roles in the aroma, complexity, and elegance of Cabernet Sauvignon wine. In this study, Cabernet Sauvignon grapes harvested in this region were fermented on an industrial scale using four commercial yeast strains (L2323, D254, RVA, and CECA) and spontaneous yeast (NF). The results showed that a total of 123 volatile compounds were detected and 15 volatile compounds significantly contributed their flavor notes to the wine’s overall aroma. The use of RVA and CECA strains resulted in wine with higher concentrations of higher alcohols, terpenes and norisoprenoids. However, the D254-fermented wine showed high level of esters and carbonyl compounds. Wine fermented with the L2323 and D254 strain possessed a stronger fruity aroma, whereas the RVA strain enhanced the herbaceous, chemical, and fatty aromas in wine. Principal component analysis revealed that a significant aromatic feature difference was observed in these wines after alcoholic and malolactic fermentation. The use of different commercial yeast strains altered the aromatic profile of Cabernet Sauvignon wine.</p

Additional file 2: Figure S1. of Using the combined analysis of transcripts and metabolites to propose key genes for differential terpene accumulation across two regions

Predication of putative monoterpenol glucosyltransferase. (A) k-means cluster of the UDP-glycosyltransferase (UGTs) transcripts in ‘Muscat Blanc a Petits Grains’. (B) phylogeny tree of UGTs based on amino acid sequences. Protein sequences are from vitis vinifera with known glucosyltransferase activity toward terpenes and biochemically characterized proteins from Vitis spp. (Vitis vinifera [Vvi] and Vitis labrusca [Vl]). Figure S2. The genes showed high homology with known terpene GTs were marked with color. Correlation of gene expression reported by the RNA-Seq and by quantitative Real-Time PCR. Data were from nine genes across four developmental stages in two years. Both the RNA-Seq values and the qRTPCR values were normalized with log2, and linear regression analysis gave an overall coefficient of variation of each gene. (ZIP 735 kb

Additional file 1: Table S1A. of Using the combined analysis of transcripts and metabolites to propose key genes for differential terpene accumulation across two regions

Statistical analysis of free terpene in ‘Muscat Blanc a Petits Grains’ berries in vitage 2010 and 2011. Table S1B. Statistical analysis of glycosidically-bound terpene in ‘Muscat Blanc a Petits Grains’ berries. Table S1C. Odour activity valuesa (OAVs) of most potent terpene volatiles in ripenning‘Muscat Blanc a Petits Grains’berries. Table S2. List of differentially expressed terpene metabolism related genes in 'Muscat Blanc a Petits Grains’ berries between CL and GT regions(GT/CL). Table S3. The Pearson's correlation coefficients between glucosyltransferase gene expression profiles and monoterpenes concentration. Table S4A. The information of UGT genes selected by phylogeny tree that showed high homology with the monoterpene glutransferease. Table S4B. The information of UGT genes selected by K means analysis. Table S5. Pearson correlation of transcriptional factors and selected genes (p < 0.05). Table S6. Differentailly-expressed transcript factor genes for the two regions at various developmental stages of grapes and their correlation with the expression of some stuctural genes in the terpene biosynthetic pathway. Table S7. Differentially-expressed genes in ABA/ethylene biosynthesis and signalling transduction pathway and their expression fold-changes. Table S8. Geographical location, soil type and climate condition of the two wine-growing regions. Table S9. List of Authentic standards and retention index run in GC-MS machine. Table S10. GenBank accession number and primers of amplified DNA fragments of genes for quantitative real-time PCR (qPCR). (XLSX 101 kb

Mass Spectrometric and Enzymatic Evidence Confirm the Existence of Anthocyanidin 3,5‑<i>O</i>‑Diglucosides in Cabernet Sauvignon (Vitis vinifera L.) Grape Berries

It has been widely accepted that anthocyanidin 3,5-<i>O</i>-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-<i>O</i>-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-<i>O</i>-diglucoside was further verified by the enzymatic evidence for the first time. Four putative 5-<i>O</i>-glucosyltransferase (5GT) genes were isolated from the Cabernet Sauvignon berries. The enzymatic analysis showed that a recombinant protein (designated as Vv5GT3) glucosylated the 3-<i>O</i>- and 5-<i>O</i>-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

Additional file 1 of Vineyard microclimate alterations induced by black inter-row mulch through transcriptome reshaped the flavoromics of cabernet sauvignon grapes

Supplementary Material