Impact of a double post-fermentative maceration with ripe and overripe seeds on the phenolic composition and color stability of Syrah red wines from warm climate

Enhancing the color and astringency of red wines through white grape seeds addition: Repurposing wine production byproducts

The clear juice fermentation technique for white wines suggests that white grape seeds, rich in flavan-3-ols and proanthocyanidins, are not effectively utilized in the winemaking process. This study incorporated 'Gewürztraminer' grape seeds into 'Cabernet Sauvignon' must before cold soak to investigate how the resultant red wines' phenolic compound profiles, color, and astringency were affected. The results showed that adding seeds primarily inhibited the leaching of flavan-3-ols from both skins and seeds. A significant increase in the levels of flavan-3-ols, tannins, and phenolic acids, as well as direct and aldehyde-bridged flavan-3-ol-anthocyanin polymers, were observed in the wines with additional seeds. This led to the improvement in the wine' red hue and its resistance to SO2 bleaching. Furthermore, the wine added with seeds exhibited stronger astringency compared to those without. The findings provide a promising winemaking strategy to improve color stability and intensify the astringency of red wines through the utilization of grape seeds.

Mannoproteins modulate olfactrory perception and copigmentation of organoleptic-active-components in wines: Effects and potential molecular mechanisms

In this research, accelerated aroma release experiments and malvidin-3-O-glucoside copigmentation experiments in model red wine solutions were designed to investigate the abilities and molecular mechanisms of mannoproteins in modulating olfactory/chromatic properties of red wines. Results indicate that under orthonasal condition, mannoprotein MP2 was promising aroma modulator due to its predictable behaviors in expelling and retaining the aroma compounds during different periods. Low field nuclear magnetic resonance and molecular dynamic simulation proved that the modulation ability of MP2 should be explained by its transitionary interacting preferences with water/aroma compound molecules. Retronasal results show that the release of aroma compounds and olfactory perceptions were irregular and difficult to predict, probably due to the complexity of the retronasal condition. All mannoproteins protected malvidin-3-O-glucoside and quercetin via the formation of binary/ternary complexes, and quercetin was found prior to be protected than malvidin-3-O-glucoside. Principal mannoprotein A0A6C1DV26 might be the critical malvidin-3-O-glucoside protector. With the presence of quercetin, principal mannoproteins B3LQU1/B5VL26 in mannoprotein MP1 might exhibit intramolecular and/or intermolecular mechanisms that strengthened the hyperchromic effect, thus enhanced the copigmentation.

Microwave Irradiation: Effects on the Change of Colour Characteristics and Main Phenolic Compounds of Cabernet Gernischt Dry Red Wine during Storage

Wine colour is an essential organoleptic property considered by consumers. In this paper, the potential effects on colour characteristics and the content of main phenolic compounds in red wine under microwave irradiation were investigated during wine storage. The results showed that the changing trend of colour characteristics of microwave-treated and untreated wines was very similar. Moreover, total phenolic compounds, total monomeric anthocyanins, main anthocyanins, main flavonoids, and main phenolic acids (gallic acid; caffeic acid; syringic acid; (+)-catechin; Cy-3-glu; Mv-3-glu) also showed similar change trends during storage. In other words, microwave irradiation had a long-term effect on the colour properties and main phenolic compounds of red wine, changes that require long-time aging in traditional processing. In terms of the studied parameters, the changes in microwave-treated wine were faster than those in untreated wine. These results showed that microwave technology, as a promising artificial aging technology, could in a short time produce red wine of similar quality to traditional aging.

Applying rosemary extract and caffeic acid to modify the composition of Monastrell wines

This work studies the effect of applying rosemary extract and caffeic acid on the polyphenolic and aromatic composition of Monastrell wines, as well as the influence of traditional winemaking or incorporating prefermentative maceration. For this purpose, three treatments were carried out in triplicate. In one of them, rosemary extract was applied on the clusters 10 days before harvest, caffeic acid was applied in the same way in another, and, finally, this acid was applied to grape before crushing. Each treatment was run by both traditional vinification and vinification with prefermentative maceration. After making wines, they were monitored for 12 months after fermentation. The application of rosemary extract, and that of caffeic acid but to a lesser extent, increased the color, the concentration of anthocyanins, and the percentage of polymerized anthocyanins, while prefermentation maceration gave rise to wines with a higher concentration of condensed tannins and polyphenols. Applying rosemary extract and caffeic acid in the vineyard also increased the concentration of esters and other compounds that favor wine aromatic quality, which was also enhanced by prefermentative maceration.

Optimisation of the methodology for obtaining enzymatic protein hydrolysates from an industrial grape seed meal residue

The grape pomace industry produces large quantities of protein-rich seeds, which can be a sustainable non-animal protein source; their techno-functional properties could be exploited to improve the colour stabilisation and modulating the astringency of red wines in warm climates. This study aims to optimise the methodology of obtaining protein hydrolysates from defatted grape seed meal residue. Five assays using different quantities of enzyme and raw materials were considered. Based on the protein purity, hydrolysates yield, colour and molecular weight distribution achieved, optimal conditions were the hydrolysis of the alkaline protein concentrate with the highest amount of enzyme. The products obtained showed the lowest colour parameters, with the lightness contributing the most to the colour differences, which were visually perceptible (ΔE*_ab > 3). The hydrophobic amino acids remained within the peptide sequence, leaving polar and charged amino acids in terminal positions, which could affect the wine equilibrium related to colour stabilisation.