Second pruning as a strategy to delay maturation in cv. ‘Touriga nacional’ in the Portuguese Douro region

Prior to winemaking, organic or mineral nitrogen compound concentrations are usually measured in the vineyard and in grape musts. These indicators facilitate vine cultivation decisions, usually through yield or vigor. During vinification, yeast and bacteria metabolize nitrogen compounds in the musts in order to generate biomass. After fermentation, the microorganisms rerelease a part of this nitrogen as soluble compounds into the wines. Another part remains bound in the lees and can be lost during racking. The must’s natural nitrogen quantities, additional supplements during fermentation, and lees contact management enhance the release of nitrogen compounds to the wines. During ageing these nitrogen compounds – primarily the amino acids – are implicated in the generation of odorous compounds such as heterocycles(1).

Non-Saccharomyces yeasts not only increase microbial diversity during wine fermentation, but also have a positive effect on improving wine aroma. Among these non-Saccharomyces yeast species, Metschnikowia pulcherrima is often studied and used in winemaking in recent years, but its application in icewine has been rarely reported. In this study, indigenous M. pulcherrima strains and Saccharomyces cerevisiae strains (commercial and indigenous strains) were sequentially inoculated for icewine fermentations; meanwhile, pure S. cerevisiae fermentations were used as the control; indigenous strains used above were screened from spontaneous fermentations of Vidal blanc icewine.

The Priorat AOC, which is situated behind the coastal mountain range of Tarragona, is characterised by a Mediterranean climate that tends towards continentality and has very little precipitation during the vegetation cycle

‘Pinot Precoce Noir’ (PPN) is an early ripening clone of ‘Pinot Noir’ (PN). The phenological differentiation is visible by an about two weeks earlier onset of veraison. It was found that the early veraison locus Ver1 on chromosome 16, previously identified in ‘Calardis Musqué’, originated from PPN. A highly correlated SSR marker, namely GF16-Ver1, was developed and tested for its ability to molecularly differentiate between PPN and PN as well as its potential to trace individual descendants.

The color of a red wine is one of the most important parameters of its quality, giving much information on its status, such as the grape variety used or the winemaking style. As the result of a complex equilibrium between different forms of anthocyanins and polymerization reactions which occur over the course of time, color can also serve as an indication of a wines’ age. For this purpose the “chemical age” i and ii indexes have been introduced by Somers in 1977. The chemical age index i measures the color absorbance after the addition of acetaldehyde while chemical index ii provides an indication of how much of the total red pigments are resistant to SO2 bleaching.