Bio-protection by one strain of M. Pulcherrima: microbiological and chemical impacts in red wines

AIM: Currently, an increasing concern from governments and consumers about environmental sustainability of wine production provides new challenges for innovation in wine industry. Accordingly, the application of more-environmentally friendly vineyard treatments against fungal diseases (powdery and downy mildew) could have a cascading impact on yeast ecology of wine production.

These days, consumers are interested in food products linked to the environment and the concept of naturalness. They prefer “free” products, such as those with no pesticide residues or no added sulfur dioxide (so2) in wines. In fact, so2 is the most widely used preservative in winemaking, as it has multiple properties at low cost: it is antioxidant, antioxidasic and antimicrobial.

In recent years, vineyards in Australia, the US, Canada, Chile, South Africa and Europe have been exposed to smoke from wildfires. Wines made from smoke-affected grapes often exhibit unpleasant smoky, ashy characters, attributed to the presence of smoke-derived volatile compounds, including volatile phenols (which occur in free and glycosylated forms). Various strategies for remediation of smoke tainted wine have been evaluated. The most effective strategies involve the removal of smoke taint compounds via the addition of adsorbent materials such as activated carbon, which can either be added directly or used in combination with nanofiltration. However, these treatments often simultaneously remove wine constituents responsible for desirable aroma, flavour and colour attributes.

In order to study the impact of climate change on Bordeaux grape varieties and to assess the adaptation capacities of candidates to the grape varieties of this wine region to the new climatic conditions, an experimental block design composed of 52 grape varieties was set up in 2009 at the INRAE Bordeaux Aquitaine center. Among the many parameters studied, the three main phenological stages of the vine (budburst, flowering and veraison) have been closely monitored since 2012. Observations for each year, stage and variety were carried out on four independent replicates. Precocity indices have been calculated from the data obtained over the 2012-2021 period (Barbeau et al. 1998). This work allowed to group the phenological behaviour of the grapevine varieties, not only based on the timing of the subsequent developmental stages, but also on the overall precocity of the cycle and the total length of the cycle between budburst and veraison. Results regarding the variability observed among the different grape varieties for these phenological stages are presented as heat maps.

Postharvest dehydration is a widely employed technique in winemaking to enhance sugar concentration and secondary metabolites from grapes. Different grape varieties exhibit varying responses in terms of dehydration rate and the resulting chemical composition.