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Sparkling wines produced using the ancestral method, also known as Pét-Nats, are gaining more and more market share these days. However, scientific information on these wines is very scarce. The aim of this study was therefore to compare the physicochemical composition and sensory characteristics of a representative selection of commercial sparkling wines produced using the ancestral and traditional methods. Ancestral sparkling wines were more heterogeneous than traditional sparkling wines, as some of them showed lower internal pressure, higher turbidity, higher color intensity and lower effervescence. These differences are probably due to the fact that the protocol for making sparkling wines using the ancestral method is not as well defined as that for traditional sparkling wines. However, the ancestral method has the advantage of being able to work with riper grapes and a lower sulfur dioxide dosage.

In this study, the effectiveness of a selected strain of Metschnikowia pulcherrima (MP1) was compared to that of sulphur dioxide for preventing white grape must from browning. Sulphur dioxide was found to drastically reduce oxygen consumption rate, protect hydroxycinnamic acids against oxidation and prevent grape must from browning, even in the presence of laccase. By contrast, supplementation with the selected strain of Metschnikowia pulcherrima (MP1) drastically increased oxygen consumption rate, thus reducing the amount of oxygen available for polyphenol oxidases. In the absence of laccase, this resulted in a decrease in browning and a certain degree of protection of the hydroxycinnamic acids, but in the presence of laccase it was not effective enough. Consequently, the selected strain of Metschnikowia pulcherrima (MP1) can be considered an interesting alternative to sulphur dioxide for preventing browning in white grape must, but only in conditions of healthy grapes.

This work compares the ancestral method for elaborating sparkling wines with the most widely used traditional method. Ancestral method is a single fermentation procedure in which the fermenting grape must is bottled before the end of alcoholic fermentation whereas traditional method involves a second fermentation of a base wine inside a bottle. Macabeo grapes were used to elaborate a traditional sparkling wine and two ancestral sparkling wines, one with a low yeast population and one with a high yeast population. The findings indicate that ancestral sparkling wines have lower ethanol content and can be elaborated using lower sulphur dioxide levels. In general, ancestral sparkling wines showed similar protein concentration, higher polysaccharide content, similar or better foamability (HM) than the traditional sparkling wine., No differences were found in the foam stability (HS). In addition, the sensory analysis indicated that ancestral sparkling wines have smaller bubble size, lower CO2 aggressivity, they seemed to have longer ageing time and were scored better than the traditional sparkling wine. These results therefore indicate that the ancestral method is of great interest for the elaboration of high-quality sparkling wines.

This work aimed to study the degradation kinetics of five grape anthocyanins caused by laccase from Botrytis cinerea. In individual solutions, the anthocyanins with three substituents in the B-ring—petunidin, delphinidin and malvidin 3-O-glucosides—were degraded much faster than those with two substituents. In the latter case, cyanidin 3-O-glucoside did not degrade as quickly, and peonidin-3-O-glucoside, in particular, was not degraded by laccase at all. In contrast, when an equimolar solution of the five anthocyanins was used, the differences in the degradation kinetics of all anthocyanins were lessened, probably because the less reactive anthocyanins were able to polymerise with the quinones formed by the laccase action on the more reactive anthocyanins. Finally, supplementation with (-)-epicatechin, glutathione and especially seed tannins seemed to protect the red colour from laccase.

Climate change has without any doubt an important impact on viticulture and oenology. The composition of wine is being altered due to lack of rainfall and the increase in temperatures during the grape ripening period; it is therefore becoming more common to find wines with low titratable acidity, high ethanol content and high pH. The increase in pH is especially problematic in sparkling wines, because they need higher acidity to maintain adequate freshness. In this research, the effects of using cation exchange on sparkling wine composition and quality was studied.

One of the problems that most seriously affects oenology today is enzymatic browning, especially when grapes are infected by grey rot. We studied the capacity of glutathione (GSH) and a specific inactivated dry yeast rich in glutathione (IDY-GSH) to protect white grape must from browning compared to that of sulphur dioxide (SO2). The results indicate that SO2 drastically reduces the oxygen consumption rate (by around 72%), protects hydroxycinnamic acids from oxidation and prevents grape must against browning even in the presence of laccase. Specifically, the presence of SO2 reduced the colour’s blue–yellow component (b*) by around 91% in control conditions and around 76% in the presence of laccase. GSH, pure or in the form of IDY-GSH, also reduces the oxygen consumption rate (by 23% and 36%, respectively) but to a lesser extent than SO2. GSH also favours the formation of grape reaction product (GRP) from hydroxycinnamic acids and effectively protects grape must against browning in healthy grape conditions. Specifically, the presence of GSH reduced b* by around 81% in control conditions. Nevertheless, in the presence of laccase, it was not effective enough, reducing b* by around 39% in the case of pure GSH and 24% in the case of IDY-GSH. Therefore, both forms of GSH can be considered as interesting alternative tools to SO2 for preventing browning in white grape must, but only when the grapes are healthy.

Climate change is affecting vine and grape physiology and consequently wine composition, causing a decrease in titratable acidity and an increase in ethanol content and pH. These effects are especially problematic in sparkling wines that need higher acidity to maintain an adequate freshness. Therefore, the wine industry is currently using certain procedures for reducing wine pH, among which cation exchange stands out as it is probably the most widely used. To study the influence of cation exchange treatment on the composition and quality of sparkling wines, a grape juice of Macabeo (pH 3.21 and titratable acidity 5.70 g of tartaric acid/L) after settling was treated to obtain a very acidic grape juice (pH 1.9 and titratable acidity 8.70 g of tartaric acid/L). The original grape juice was then blended in different proportions (0-45 %) with a treated grape juice. These different grape juices were used for obtaining their corresponding base wines which in turn were used for elaborating their corresponding sparkling wines using the traditional method. The cation exchange treatment reduced the pH from 3.15 (Control) to 2.87 (45 % of treatment) and increased the titratable acidity from 4.61 (Control) to 7.69 (45 % of treatment). No significant effects were observed on the concentration of any of the protein or polysaccharide fractions and the foaming properties of the base wine or young sparkling wines were not affected; however, cation exchange caused a decrease in foamability and persistence of the foam in older sparkling wines, especially when the proportion of treated grape juice was higher. A trained panel only found clear sensory differences in the acidity of the sparkling wines without the rest of the attributes being affected by the treatment.