Inter- and intra-varietal genetic variations co-shape the polyphenol profiles of Vitis vinifera L. grapes and wines

Inheritance and mutations are important factors affecting grape phenolic composition. To investigate the inter- and intra-varietal differences in polyphenolic compounds among grapes and wines, 27 clones belonging to eight varieties of Vitis vinifera L. were studied over two consecutive years. A total of 24 polyphenols (nine anthocyanins, three flavanols, five flavonols, and seven phenolic acids) were analyzed, and the physicochemical parameters of the grapes and wines were determined. Polyphenol profiles showed significant varietal and clonal polymorphisms, and malvidin-3-O-glucoside, peonidin-3-O- glucoside, and epicatechin were identified as key biomarkers distinguishing different grapes and wines when using an orthogonal partial least squares discriminant analysis. Further multivariate analysis classified these genotypes into three subclasses, and a somatic variant of 'Malbec', MBVCR6, had the most abundant polyphenolic compounds that were related to the titratable acid content. The current results reveal that varietal and clonal variations are important for obtaining wines with high polyphenol content.

Cold plasma treatment to improve germination and enhance the bioactive phytochemical content of germinated brown rice

The changes in the bioactive phytochemicals of six cultivars of Thai germinated brown rice (GBR) were monitored in parallel to those of cold plasma-treated GBR (PGBR). After treatment with the optimal plasma conditions, the germination percentage, root length, and seedling height measurements of the most sensitive rice cultivar increased by 84%, 57%, and 69%, respectively. For all of the rice cultivars, there were no significant differences in the antioxidant activities of the GBRs and PGBRs. Conversely, higher contents of γ-oryzanols were observed in the PGBR group than in the GBR group during the 2-day germination period. Certain cultivars in the PGBR group reached their maximum values for total phenolic compounds, total vitamin E, certain simple phenolics, phytosterols, triterpenoids, and anthocyanins one day earlier than the same values for GBR. In contrast, the concentrations of 2-acetyl-1-pyrroline in both the GBR and PGBR samples were reduced significantly with increased germination time.

Dynamic changes in anthocyanin biosynthesis regulation of Cabernet Sauvignon (Vitis vinifera L.) grown during the rainy season under rain-shelter cultivation

The grapevine (Vitis vinifera L.) berry coloring mechanism in response to seasonal rain during grape ripening remains poorly understood. Therefore, anthocyanin biosynthesis regulation, dynamic changes in anthocyanin accumulation, biosynthetic enzyme activities, and related gene expression patterns were investigated in Cabernet Sauvignon grown under rain-shelter cultivation and open-field cultivation. Results showed that anthocyanin biosynthesis was strongly repressed during the rainy season. Environmental fluctuation from seasonal rain provoked metabolic responses in grapes, and there was a significantly greater accumulation of most of the anthocyanins, mainly the compositions of non-acylated and non-methylated, under rain-shelter cultivation; these findings indicate that rain-shelter cultivation may help improve tolerance to seasonal rain-induced stresses. Obvious resilience was observed in anthocyanins of open-field-cultivated grapes at harvest. Hierarchical cluster analysis indicated strong correlations between anthocyanin contents, CHI and DFR activities, and VvMYB5b transcriptional level. These findings provide novel insight into the crucial factors that directly modulate anthocyanin biosynthesis and consequently control grape coloration.

Anthocyanin copigmentation and color of wine: The effect of naturally obtained hydroxycinnamic acids as cofactors

Copigmentation of anthocyanins accounts for over 30% of fresh red wine color, while during storage, the color of polymeric pigments formed between anthocyanins and proanthocyanidins predominates. Rosmarinic acid and natural extracts rich in hydroxycinnamic acids, obtained from aromatic plants (Origanum vulgare and Satureja thymbra), were examined as cofactors to fresh Merlot wine and the effect on anthocyanin copigmentation and wine color was studied during storage for 6months. An increase of the copigmented anthocyanins that enhanced color intensity by 15-50% was observed, confirming the ability of complex hydroxycinnamates to form copigments. The samples with added cofactors retained higher percentages of copigmented anthocyanins and higher color intensity, compared to the control wine, up to 3 months. However, the change in the equilibrium between monomeric and copigmented anthocyanins that was induced by added cofactors, did not affect the rate of polymerization reactions during storage.

Bioactive potential of Vitis labrusca L. grape juices from the Southern Region of Brazil: phenolic and elemental composition and effect on lipid peroxidation in healthy subjects

Grapes are rich in polyphenols with biologically active properties. Although the bioactive potential of grape constituents are frequently reported, the effects of Brazilian Vitis labrusca L. grape juices ingestion have not been demonstrated in humans. This study identified the phenolic and elemental composition of red and white grape juices and the effect of organic and conventional red grape juice consumption on lipid peroxidation in healthy individuals. Concentrations of anthocyanins, flavanols and phenolic acids and the in vitro antioxidant activity were significantly higher in the organic juice. The macro-elements K, Ca, Na and Mg were the most abundant minerals in all juices. The acute consumption of red grape juices promoted significant decrease of lipid peroxides in serum and TBARS levels in plasma. It is concluded that red V. labrusca L. grape juices produced in Southern Brazil showed lipid peroxidation inhibition abilities in healthy subjects, regardless of the cultivation system.