Effects of gibberellic acid (GA3 ) application before anthesis on rachis elongation and berry quality and aroma and flavour compounds in Vitis vinifera L. 'Cabernet Franc' and 'Cabernet Sauvignon' grapes.

BACKGROUND: Gibberellic acid (GA3 ), a plant-growth regulator, is often used to obtain enlarged table grape berries and induce seedlessness in them. However, the effects of GA3 on rachis elongation and bunch compactness have seldom been reported in wine-grape production. We assessed the effects of GA3 spraying on wine-grape inflorescences and bunches and their practical implications for viticulture in the Jiaodong Peninsula, China. RESULTS: Various GA3 concentrations were sprayed on field-grown Vitis vinifera L. 'Cabernet Franc' (CF) and 'Cabernet Sauvignon' (CS) grapevines before anthesis in the Jiaodong Peninsula, China, in 2015 and 2016. Inflorescence length during berry development was measured, and flavonoids and aroma compounds in the fruit were detected by high-performance liquid chromatography - mass spectrometry (HPLC-MS) and gas chromatography - mass spectrometry (GC-MS), respectively. For both cultivars, 50 and 100 mg L-1 GA3 caused significant elongation of the rachis, whereas there was no significant effect on inflorescence growth and berry seed number. Anthocyanin, flavonol, and flavan-3-ol levels in mature berries were not significantly influenced by GA3 spraying, whereas C13 -norisoprenoids were modified. CONCLUSION: The application of 50-100 mg L-1 GA3 prior to grapevine anthesis caused elongation of inflorescences and bunches, and eased cluster compactness in CF and CS, and no negative effects were observed on the yield and seed numbers. The concentration and composition of flavonoids and most aroma compounds were not influenced, except that the norisoprenoids were increased by 50 mg L-1 GA3 applications. © 2020 Society of Chemical Industry.

Dibasic Ammonium Phosphate Application Enhances Aromatic Compound Concentration in Bog Bilberry Syrup Wine.

A nitrogen deficiency always causes bog bilberry syrup wine to have a poor sensory feature. This study investigated the effect of nitrogen source addition on volatile compounds during bog bilberry syrup wine fermentation. The syrup was supplemented with 60, 90, 120 or 150 mg/L dibasic ammonium phosphate (DAP) before fermentation. Results showed that an increase of DAP amounts accelerated fermentation rate, increased alcohol content, and decreased sugar level. Total phenol and total flavonoid content were also enhanced with the increase of DAP amounts. A total of 91 volatile compounds were detected in the wine and their concentrations were significantly enhanced with the increase of DAP. Ethyl acetate, isoamyl acetate, phenethyl acetate, ethyl butanoate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, isobutanol, isoamyl alcohol, levo-2,3-butanediol, 2-phenylethanol, meso-2,3-butanediol, isobutyric acid, hexanoic acid, and octanoic acid exhibited a significant increase of their odor activity value (OAV) with the increase of DAP amounts. Bog bilberry syrup wine possessed fruity, fatty, and caramel flavors as its major aroma, whereas a balsamic note was the least present. The increase of DAP amounts significantly improved the global aroma attributes, thereby indicating that DAP supplementation could promote wine fermentation performance and enhance the sensory quality of bog bilberry syrup wine.

Polyphenolic Compositions and Chromatic Characteristics of Bog Bilberry Syrup Wines.

Phenolic compounds determine the color quality of fruit wines. In this study, the phenolic compound content and composition, color characteristics and changes during 6 months of bottle aging were studied in wines fermented with bog bilberry syrup under three different pHs. The total anthocyanins and total phenols were around 15.12-16.23 mg/L and 475.82 to 486.50 mg GAE/L in fresh wines and declined 22%-31% and about 11% in bottle aged wines, respectively. In fresh wines, eight anthocyanins, six phenolic aids and 14 flavonols, but no flavon-3-ols were identified; Malvidin-3-O-glucoside, petunidin-3-O-glucoside and delphinium-3-O-glucoside were the predominant pigments; Chlorogentic acid was the most abundant phenolic acid, and quercetin-3-O-galactoside and myricetin-3-O-galactoside accounted for nearly 90% of the total flavonols. During 6 months of bottle storage, the amounts of all the monomeric anthocyanins and phenolic acids were reduced dramatically, while the glycosidyl flavonols remained constant or were less reduced and their corresponding aglycones increased a lot. The effects of aging on blueberry wine color were described as the loss of color intensity with a dramatic change in color hue, from initial red-purple up to final red-brick nuances, while the pH of the fermentation matrix was negatively related to the color stability of aged wine.

The combined influence of rootstock and vintage climate on the grape and wine flavonoids of Vitis vinifera L. cv. Cabernet Sauvignon in eastern China.

Rootstocks are commonly utilized owing to their resistance to abiotic and biotic stress in viticulture. This study evaluated the effects of three rootstocks (1103P, SO4, and 5A) on the Cabernet Sauvignon (CS) vine growth, and their berries and wines flavonoids profiles in four consecutive vintages. The results showed that 1103P increased the pruning weight of CS and decreased the anthocyanin concentration in berries and wines, especially in the vintages with more rainy and cloudy days. 5A tended to decrease the pruning weight of CS and increase the anthocyanin concentration in berries and wines. Orthogonal partial least squares discriminant analysis (OPLS-DA) showed that the concentrations of total anthocyanins, F3'H-anthocyanins, malvidin-3-O-glucoside (Mv-glu), and malvidin-3-O-acetylglucoside (Mv-acglu) were the key substances affected by the rootstocks in CS berries and were significantly decreased by 1103P. Total anthocyanins, pinotins, Mv-glu, epicatechin, and vitisins were the rootstock-sensitive compounds that commonly differed in wines among the three comparison groups in the two vintages. Furthermore, 1103P brought more brightness to the wine and 5A gave the wine more red tones. In conclusion, rootstock 5A was recommended in the rainy and cloudy climate regions with regard to the berry flavonoids accumulation and the wine color.