Bioactive compounds recovery by freeze concentration process from winemaking by-product.

Grape pomace is the main solid residue of wine industry, containing high amounts of phenolic compounds. Considering its high potential, an extraction procedure was optimized for maximal recovery of anthocyanins from grape pomace (Vitis vinifera L.) using citric acid as a generally recognized as safe (GRAS) acidulant in water. Volume of solvent (3.2-36.8 mL), time (14.4-165.6 min) and pH of solvent (1.12-4.48) were the studied variables. Furthermore, the best condition to obtain extract rich in anthocyanins was submitted to the gravitational block freeze concentration process. The performance of the process was evaluated and cryoconcentrated and ice fractions were analyzed for physicochemical properties, bioactive compounds content, and antioxidant activity. Interaction, linear, and quadratic effects for volume and pH of solvent were significant by analysis of variance (ANOVA). The experimental design allowed the prediction for maximal recovery of anthocyanins (10 mL of solvent at pH 1.8). The bioactive composition of the optimized grape pomace extract was influenced by the cryoconcentration process. After three cycles using gravitational block freeze concentration, the total phenolics and monomeric anthocyanins were approximately 4 and 5 times higher than the initial condition of the extract, respectively. Consequently, an increase in antioxidant activity was observed. The increase in the concentration of bioactive compounds reached a process efficiency of 93% (stage 1) for phenolic compounds and 91% (stage 2) for anthocyanins. Therefore, the final water-based optimized method is safe and has a low cost and the concentrated extract certainly showed higher concentrations of total phenolics and anthocyanins, compared to the initial extract. The proposed clean extraction method and cryoconcentration technique can be considered important strategies for recovering and valuing grape pomace components, improving the approach to the circular economy concept in the wine industry.

Changes in vineyard productive attributes and phytochemical composition of sauvignon blanc grape and wine induced by the application of silicon and calcium.

BACKGROUND: It is important to increase productivity and improve plant quality at the same time as preserving the principles of safety and productivity. The present study aimed to evaluate the effects of different concentrations of sodium metasilicate and calcium chloride, applied as fertilizers, on the productivity and phytochemical characteristics of Sauvignon Blanc grapes and their respective wines. RESULTS: The experiments were conducted using 2017 and 2018 vintages of commercial Sauvignon Blanc grapes. The treatments consisted of applying separately different concentrations of sodium metasilicate (0, 4, 8 and 12 g L-1 ) or calcium chloride (0, 5, 10 and 15 g L-1 ). The treatments were carried out during four phenological phases. The grapes were harvested at technical maturity and white wines were elaborated. The application of inorganic salts, silicon and calcium to the grapes had a significant effect on the vineyard productivity. The best results were obtained with 4 and 8 g L-1 silicon and 15 g L-1 calcium. An increase in the concentration of phenolics in the grapes was noted. These compounds have antioxidant capacity, which is one of the factors responsible for the resistance of the grapes to pathogens. CONCLUSION: The application of 4 and 8 g L-1 silicon and 15 g L-1 calcium to the grapes represents a potential alternative fertilizing strategy, which could increase the plant yield without damaging the phytochemical characteristics of the fruit and its derivatives. © 2020 Society of Chemical Industry.

Rosé Sparkling Wines: Influence of Winemaking Practices on the Phytochemical Polyphenol During Aging on Lees and Commercial Storage.

The effects of oenological agents, gum arabic, and oenological tannin, added at two different stages in the winemaking of rosé sparkling wines (addition to the base wine and to the sparkling wine after disgorging) on evolution of the phytochemical composition during aging on lees and commercial storage were studied for the first time. The sparkling wines were monitored during 12 months of aging on lees (sur lie, with lees) and commercial storage (bottle storage, without lees), in terms of the polyphenolics, color intensity and antioxidant capacity. It was observed that the stage of the addition of oenological agents influenced the changes in phytochemical polyphenols and antioxidant capacity of sparkling wines. The most notable effects on the polyphenolics were observed in the experiment with the addition of oenological agents to the base wine, which significantly increased the concentrations of trans-resveratrol, gallic and ellagic acids, catechin, quercetin, and myricetin. The addition of oenological agents after the disgorging stage had less influence on the phenolics of the sparkling wines. Caffeic acid, trans-caftaric acid, catechin, tyrosol, and gallic acid were the most abundant polyphenolics in rosé sparkling wines. The winemaking practices evaluated in this study comprise an interesting approach to the improvement and/or maintenance of the polyphenolics, according to winemaking practices, besides providing new knowledge on the evolution of rosé sparkling wines. PRACTICAL APPLICATIONS: Tannins and gum arabic are been described as oenological agents, however, are poorly explored in rosé sparkling wines. Many chemical modifications that occur during the winemaking process, especially due to the second in-bottle fermentation and the yeast contact in the case of sparkling wines, can be determinant of authenticity and quality of sparkling wines. The addition of oenological agents in different stages of the winemaking can provide new insights into the evolution of phytochemical constituents of rosé sparkling wines and draw perspectives for improving technological properties of these wines based on practical experience.