Monitoring of microbial biomass to characterise vineyard soils

Grape harvest time is one of the most fundamental aspects that affect grape quality and thus wine quality. Many factors influence the decision of harvest; among them technological and phenolic maturity of grape. Technological ripeness is mainly related to sugar concentration, titratable acidity and pH. Conventional methods for chemical analysis of grapes are normally sample-destructive, time-consuming, include laborious sample preparation steps, and generate chemical waste, thereby limiting their utility in online/in-line quality monitoring. Moreover, destructive analyses can be performed only on a limited number of fruit pieces and, thus, their statistical relevance could be limited. This study evaluated the ability of a lab-scale hyperspectral imaging (HYP-IM) technique to predict titratable acidity, organic acid and sugar content of grapes. Samples of Cabernet franc and Chenin blanc grapes were consecutively collected six times at weekly intervals after veraison. The images were recorded thanks to the hyperspectral imaging camera Pica L (Resonon) in a spectral range from 400 to 1000 nm. Statistics were performed using Microsoft Xlstat software. Successively, the berries were analyzed for their sugar (glucose and fructose) and organic acid (malic and tartaric acid) content and titratable acidity according to usual methods.

The grape maturation process is being affected by the consequences of global climate change and, as a result, there is a gap at harvest time between the technological maturity of grapes (mostly the concentration of sugar and acids) and its phenolic quality. Due to this gap, the wines elaborated using those grapes show a non-adequate phenolic composition, which results in defects on its color and astringency characteristics. Astringency is mainly related to the salivary protein precipitation because of the interaction not only with wine flavanols but also with other wine phenolics, such as flavonols or different pigments.

Phenolic compounds are among the most important quality factors of wines. They contribute to the organoleptic characteristics of wine such as colour, astringency, and bitterness. Although tannins found in wine can come from microbial and oak sources, the main sources of polyphenols are skin and seed from grapes. Yet, the link between grape seed phenolic content and wine composition, or even the link between seed maturity stage and wine composition are poorly studied. This work describes and explains the seed tannins kinetics release in wine, but also the impact of seed maturity stage on seed tannins extractability.

When talking about terroir, scientists and lay wine tasters, very much including wine journalists and wine growers, too often talk past one another.

Bud fruitfulness is a key component of reproductive performance of grapevine. It plays a significant role in annual yield variation of vineyards as it is a prerequisite of crop production in the following season. Various exogenous and endogenous factors influencing the development of inflorescence primordia (IP) have been studied. However, the research on molecular genetic control of bud fruitfulness, especially how it interacts with environmental factors is still lacking. This study aims to investigate the molecular mechanism of effects of temperature and light on grapevine bud fruitfulness during initiation and differentiation of IP.