Improving stilbenes in vitis Labrusca L. Grapes through methyl jasmonate applications

Nutrient availability – nitrogen, lipids, vitamins or oxygen – has a major impact on the kinetics of winemaking fermentations. Nitrogen is usually the growth-limiting nutrient and its availability determines the fermentation rate, and therefore the fermentation duration. In some cases, in particular in Champagne, grape musts have high nitrogen concentrations and are sometimes clarified with turbidity below 50 NTU. In these conditions, lipid deficiencies may occur and longer fermentations can be observed. To better understand this situation, a study was realized using a synthetic medium simulating the composition of a Champagne must : 180 g/L of sugar, 360 mg/L of assimilable nitrogen and a lipid content ranging from 1 to 8 mg/L of phytosterols (mainly β-sitosterol).

Context and purpose of the study. Modern conventional agriculture, including viticulture, relies greatly on the use of chemical inputs, especially synthetic pesticides.

Ozalj- vivodina region is small vine growing area (only about 100 hectares of vineyards), but with significant number of old, ancient vineyards planted between 50 and 100 years ago. Trend of abandoning or replanting ancient vineyards takes place for the last 30 years. This trend results in grapevine germplasm erosion because traditional varieties are replaced with well known international varieties.Few known traditional varieties are dominantly present in ancient vineyards together with many others of unknown identity. Historical data about prevalence and characteristic of varieties on this area are very poor.

Bottle ageing is a critical period for wine quality, as it undergoes various chemical and sensory changes during storage. Ideally, a phase of qualitative ageing, during which wine sensory quality improves, is followed by a decline of quality. Understanding how different oenological variables influence these phases is a key challenge in modern winemaking. Recent studies highlighted the significant role of oxygen in modulating reactions involving volatile and non-volatile components, impacting aroma evolution during bottle aging. Oxygen exposure of wine during bottle ageing is mediated by closure.

The management of yeast nutrition is an essential approach for a better control over wine fermentation process. Most of the researches on this subject in the last decades focused on nitrogen nutrition. However, vitamins, while being key compounds for yeast metabolism as co-factors for numerous enzymatic activities, were left mostly unexplored.