Variability in intrinsic water use efficiency (WUEi) of eight red varieties grown in the center of the Iberian Peninsula during an atypical vintage year

Nitrogen (N) nutrition of the vineyard plays a crucial role in the composition of must and wine, impacting fermentation, as well as the aroma and taste of the final product. N-deficient grape juice can result in increased astringency and bitterness, and a decrease in pleasant aromas in the wine.

Malolactic fermentation (MLF) is a desired process in red and acidic white wines, after alcoholic fermentation (AF), carried out by the lactic acid bacterium (LAB) Oenococcus oeni. The advantages are an increase of pH, microbiological stabilization and organoleptic improvement of the final wine. However, the presence of stress factors such as ethanol, low pH, high total SO2, lack of nutrients and presence of inhibitors, could affect the successful completion of MLF [1]. Changes in amino acid composition and deficiencies in peptides after AF, showed that MLF can be delayed, signaling its importance for bacterial growth and L-malic acid degradation during MLF [2].

In the present study the connection between the positional candidate gene VvDXS and muscat flavor was evaluated by investigating the expression profiles in the berries from a Muscat-type cultivar and a neutral cultivar and its nucleotide diversity of full ORF on grapevine accessions.

Volatile sulphur compounds are a group of impact odorants with low odour thresholds that can contribute both positively and negatively to wine aroma. The varietal thiols, 3MH and 3MHA, are known to contribute positive tropical aromas to white wines and are most abundant in Sauvignon Blanc wines. The group of compounds contributing negative aromas are known as reductive sulphur compounds (RSCs) as they add a reductive aroma of asparagus, cooked vegetables and rotten egg to wines. All these compounds play a part in and are a result of the sulphur pathway in the yeast cell during fermentation and therefore attempting to increase the concentration of the varietal thiols may directly influence the concentration of the RSCs. The varietal thiols and the low molecular weight RSCs are highly volatile and therefore their sensory perception can change rapidly over time.

Context and purpose of the study. The vine nursery sector is undergoing a transformation to meet growing environmental and sanitary demands.