What happens with the glutathione during winemaking and the storage of the wine?

Water status impact in viticulture has been widely explored, as it strongly affects grapevine physiology and grape chemical composition. It is considered as a key component of vitivinicultural terroir. Most of the studies concerning grapevine water status have focused on either physiological traits, or berry compounds, or traits involved in wine quality. Here, the response of grapevine to water availability during the ripening period is assessed through non-targeted metabolomics analysis of grape berries by ultra-high resolution mass spectrometry. The grapevine water status has been assessed during 2 consecutive years (2019 & 2020), through carbon isotope discrimination on juices from berries collected at maturity (21.5 brix approx.) for 2 Vitis vinifera cv. Pinot noir (PN) and Chardonnay (CH). A total of 220 grape juices were collected from 5 countries worldwide (Italy; Argentina; France; Germany; Portugal). Measured δ13C (‰) varied from -28.73 to -22.6 for PN, and from -28.79 to -21.67 for CH. These results also clearly revealed higher water stress for the 2020 vintage. The same grape juices have been analysed by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) and Liquid Chromatography coupled to Mass Spectrometry (LC-qTOF-MS), leading to the detection of up to 4500 CHONS containing elemental compositions, and thus likely tens of thousands of individual compounds, which include fatty acids, organic acids, peptides, phenolics, also with high levels of glycosylation. Multivariate statistical analysis revealed that up to 160 elemental compositions, covering the whole range of detected masses (100 –1000 m/z), were significantly correlated to the observed gradients of water status. Examples of chemical markers, which are representative of these complex fingerprints, include various derivatives of the known abscisic acid (ABA), such as phaesic acid or abscisic acid glucose ester, which are significantly correlated with higher water stress, regardless of the variety. Cultivar-specific behaviours could also be identified from these fingerprints. Our results provide an unprecedented representation of the metabolic diversity, which is involved in the water status regulation at the grape level, and which could contribute to a better knowledge of the grapevine mitigation strategy in a climate change context.

Most of the effects of ultrasound (US) result from the collapse of bubbles due to cavitation. The shockwave produced is associated with shear forces, along with high localised temperatures and pressures. However, the high-speed stream, radical species formation, and heat generated during sonication may also affect the stability of some enzymes and proteins, depending on their chemical structure. Recently, Ce-lotti et al. (2021) reported the effects of US on protein stability in wines. To investigate this further, the effect of temperature (40°C and 70°C; 60s), sonication (20 kHz and 100 % amplitude, for 20s and 60s, leading to the same temperatures as above, respectively), in combination with Aspergillopepsins I (AP-I) supplementation (100 μg/L), was studied on unstable protein concentration (TLPs and chitinases) using HPLC with an UV–Vis detector in a TLPs-supplemented model system and in an unstable white wine.

Scientific information on grapevine response to predicted levels of climate parameters is scarce and not sufficient to properly position the Wine Industry for the future. It is critical that the combined effects of increased temperature and CO2 on grapevines should be examined, without omitting the important link to soil water conditions. The purpose of this study is to quantify the effects of envisioned changes in climatic parameters on the functioning and growth of young grafted grapevines under controlled conditions, simulating expected future climate changes. Scientific knowledge of precisely how the newly-planted grapevine will react morphologically, anatomically and physiologically (at leaf, root and whole plant level) to the expected changes in important climatic parameters will enable producers to make better-informed decisions regarding terroir, cultivar and rootstock choices as well as the adaptation of current cultivation practices.

Atmospheric and statistical models were used to increase understanding of potential climatic impacts, resulting from mesoscale physical processes that cause significant temperature variability for viticulture within the Stellenbosch Wine of Origin district. Hourly temperature values from 16 automatic weather stations and 40 tinytag data loggers located in the vineyards were analysed.

The first forms of life on earth were bacteria and single-celled blue-green algae. They evolved into land plants around 500 million years ago, developing mechanisms for surviving on land, such as roots, stems and leaves. This evolution also led them to coexist with other organisms, such as insects and animals, for pollination and seed dispersal, as well as to resist environmental factors such as drought and disease.