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The main conclusion of this study is that the foaming properties of wines can be improved if harvest dates are advanced.

The aim of this paper is to study the real influence of seeds and stems on wine composition, astringency, and bitterness. A decolored grape juice and a grape juice macerated for 4 days from the same Cabernet Sauvignon grapes were fermented with or without supplementation with 100% seeds, 300% seeds, or 100% stems. Once alcoholic fermentation had finished, the wines were analyzed and tasted. The presence of seeds and stems increased the concentration of flavan-3-ol monomers with respect to the controls. However, the seeds mainly released (+)-catechin and (-)-epicatechin, whereas the stems mainly released (+)-catechin and (+)-gallocatechin. The seeds and stems also released proanthocyanidins; those from seeds have a lower mDP and a high percentage of galloylation, whereas those from stems have a higher mDP and a relatively high percentage of prodelphinidins. The presence of seeds and stems brought about a slight but significant increase in pH and lowered titratable acidity and ethanol content. The presence of seeds boosted color intensity, whereas stems had the opposite effect. Finally, both seeds and stems increased wine astringency and bitterness.

It can be concluded that supplementation with inactive yeasts is indeed a useful tool for smoothing the astringency of red wines. © 2016 Society of Chemical Industry.

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Abstract. In a previous study we reported that sequential inoculation of Torulaspora delbrueckii and Saccharomyces cerevisiae during the first fermentation increased the protein concentration and improved the foaming properties of a base wine. Since effervescence and foam of sparkling wines are key quality factors, the interest of this practice for sparkling wine industry is obvious. In this paper we study whether the foaming properties of the sparkling wines produced from the base wines obtained by sequential inoculation with T. delbrueckii and S. cerevisiae remains better than those of their controls produced from base wines fermented only with S. cerevisiae. The obtained results confirmed that sequential inoculation in the production of the base wine originated sparkling wines with significantly higher maximum heights of foam than conventional inoculation, probably because autolysis of the T. delbrueckii cells in the base wine released higher amounts of proteins, especially of the low molecular weight fraction.

Different sparkling wines were elaborated with a base wine of Macabeo from the AOC Cava using the traditional method with supplementation or not of inactivated dry yeasts of Saccharomyces cerevisiae (Optimumwhite TM) or Torulaspora delburueckii (TD291). After 9 months, the samples were analyzed and tasted. The supplementation with both IDY (S. cerevisiae and T. delbrueckii) produced Cavas with better foaming properties than the Cava control. The tasters could significantly distinguish between the Cavas supplemented with both IDY from the Cava control. Moreover, taster clearly preferred the Cava elaborated with supplementation of IDY of T. delburueckii than the control one. This study has been funded by CDTI (CIEN-VINySOST2014 project).