Modification of wine phenolic profiles by gibberellic acid application in 'Cabernet Gernischt' grapevines before anthesis.

BACKGROUND: Vitis vinifera L. 'Cabernet Gernischt' grapes from the Yantai wine region of China usually form dense clusters and contain low phenolic content. We applied five concentrations (ranged from 5 to 25 mg L-1 ) of gibberellic acid (GA3 ) to 'Cabernet Gernischt' before anthesis to decrease cluster compactness in two consecutive vintages. Yield indices, grape maturity, and wine phenolic compounds were determined. RESULTS: GA3 application significantly reduced cluster compactness, bunch weight, and yield per vine, but it did not significantly improve fruit ripening. The levels of total phenolics, total tannins, and total anthocyanins in wine were enhanced by GA3 application, with 10 and 15 mg L-1 GA3 treatments consistently producing a significant increase in the concentrations of mavidin, cyanidin, and their derivatives. Specifically, trans-resveratrol was consistently significantly increased by 15 mg L-1 GA3 application. Principal component analysis of phenolic compounds demonstrated the differences among wines produced from GA3 treatment groups and the control. CONCLUSION: Overall, wine phenolic profiles could be significantly modified by application of low concentrations of GA3 before anthesis. Application of high levels of GA3 is not recommended due to significant yield decrease. © 2022 Society of Chemical Industry.

Reduced nitrogen fertilization from pre-flowering to pre-veraison alters phenolic profiles of Vitis vinifera L. Cv. Cabernet Gernischt wine of Yantai, China.

Nitrogen (N) fertilization is important for grape growth and wine quality. Unreasonable N fertilizer application affects wine growth and has a negative impact on wine quality. Therefore, it is essential to address the mismatch between N application and wine composition. To regulate vine growth and improve grape and wine quality, Cabernet Gernischt (Vitis vinifera L.) grapevines were subjected to lower levels of N, compared to normal N supply treatments, during the grape growing seasons of 2019 and 2020 in the wine region of Yantai, China. The effects of reduced N application from pre-boom to pre-veraison on vine growth, yield and composition of grapes, and dry red wine anthocyanin and non-anthocyanin phenolic compound content were studied. We found that reduced N application significantly decreased dormant shoot fresh mass and yield. However, the effect of N application on fruit ripening depended on the season. Nitrogen-reduction treatment significantly improved wine phenolic parameters, including total phenolics, tannins, and anthocyanins, and enhanced most of the individual anthocyanins and some non-anthocyanin phenolics, especially stilbenes, including piceatannol, trans-resveratrol, and polydatin, regardless of the season. Overall, our findings highlight the importance of reducing N application during the grape growing season in order to modify the wine phenolic profiles.

Multi-objective evaluation of freshly distilled brandy: Characterisation and distribution patterns of key odour-active compounds.

The characterisation and distribution patterns of key odour-active compounds in head, heart1, heart2, tail, and stillage cuts of freshly distilled brandy were investigated by gas chromatography-olfactometry-mass spectrometry coupled with aroma extract dilution analysis (AEDA) and chemometrics analysis. Results from AEDA showed that there were 50, 61, 48, 25, and 18 odour-active compounds in the head, heart1, heart2, tail, and stillage cuts, respectively. Besides, 19, 22, 11, 5, and 4 quantified compounds with odour activity values ≥ 1, respectively, were considered to be potential contributors to the aroma profile of different distillation cuts. Especially, the chemometrics analysis illustrated the heart1 fraction was characterized by 3-methylbutanol, ethyl hexanoate, 1-hexanol, ethyl octanoate, benzaldehyde, ethyl decanoate, and 2-phenylethyl acetate; (E)-hex-3-en-1-ol, (Z)-hex-3-en-1-ol, and 2-phenylethyl acetate greatly contributed to the characteristics of the heart2 cut. Furthermore, different volatile compounds with a variety of boiling points and solubilities followed diverse distillation rules during the second distillation. Our findings may provide a rational basis for concentrating more pleasant aroma components contributing to brandy.

Co-winemaking with Vitis amurensis Rupr. "Beibinghong" enhances the quality of Vitis vinifera L. cv. Cabernet Gernischt wine.

In some wine regions of China, Cabernet Gernischt (CG; Vitis vinifera L.) grape berries usually exhibit low pigment content and titratable acidity, and low sensory quality of the resulting wine. The aim of this study was to evaluate co-winemaking of CG wines using the red grape cultivar Beibinghong (BBH; Vitis amurensis Rupr.) at different proportions in terms of alcohols, phenolic compounds, and sensory properties of the wines. The results showed that the co-winemaking wines contained a similar content of higher alcohols, whereas the methanol content increased with an increase in BBH proportion, although this was still corresponded with the national standard. Significantly higher levels of titratable acidity were observed in co-winemaking wines at the ratio of 6:4 and 5:5, compared with monocultivar CG wines. All co-winemaking wines, except CG:BBH (9:1) wine, showed significantly higher levels of total anthocyanins, total phenolics, total tannins, and total flavan-3-ols. Further, individual phenolics, primarily diglucoside anthocyanins and non-anthocyanins (trans-ferulic acid, myricetin, viniferin, trans-caffeic acid, 3,4-dihydroxybenzoic acid), as important contributors to wine color intensity, permitted the differentiation of the wines via principal component analysis. In most cases, co-winemaking wines exhibited higher scores of the 10 sensory attributes on color, aroma, mouthfeel, and overall quality compared with monocultivar wines. Co-winemaking CG wines with BBH at 7:3 ratio demonstrated the highest scores of color intensity, aroma intensity, aroma quality, and overall quality. The results indicate that co-winemaking with V. amurensis grape variety may be useful to enhance V. vinifera wine quality by modifying wine composition. PRACTICAL APPLICATION: Cabernet Gernischt (CG) is the predominant grape cultivar used to prepare premium-quality wine in China; however, in some wine regions, CG wines have low levels of pigment and titratable acidity, and low sensory quality. Co-winemaking with another native grape cultivar, Beibinghong (BBH), which is characterized by a higher content of anthocyanins and acidity, provided sufficient experimental evidence of adjustments in the Vitis vinifera wine composition leading to improved wine sensory quality.

Characterization of volatile aroma compounds in litchi (Heiye) wine and distilled spirit.

This study used litchi (Heiye) wine and distilled spirit as raw experimental materials to analyze the volatile aroma compounds. Qualitative and quantitative determination of aromatic components was studied using stir bar sportive extraction (SBSE) and gas chromatography coupled to mass spectrometry (GC/MS). Results indicated that a total of 128 different types of aroma compounds were observed, which belonged to six chemical groups, including 39 esters, 16 alcohols, 16 acids, 22 terpenes, 17 aldehydes and ketones, and 18 other compounds. In particular, esters were the highest among all six categories and represented approximately 52% of the total flavor component content in litchi distilled spirit. The odor activity values (OAVs) revealed 22 types of aroma compounds with OAVs >1 in this test. It is possible that the produced litchi distilled spirit had a stronger varietal character due to the increased concentrations and OAVs of ß-damascenone, linalool, ethyl butyrate, ethyl isovalerate, ethyl caproate, trans-rose oxide, and cis-rose oxide. Taking the OAVs into account, we evaluated the characteristic aromas for litchi wine and litchi distilled spirit.