Simulated climate change in a Mediterranean organic vineyard altered the plant physiology and decreased the vine production

The global consumer demand for low or non-alcoholic wine is growing steadily in recent years, driven by health concerns, religious beliefs, and personal taste preferences etc.. Consequently, the removal of alcohol from wine can significantly alter its chemical and sensory properties, including color, aroma, and taste, which make a significant challenge for consumer to accept these products. Ethanol plays a crucial role in various chemical reactions and interactions that contribute to the development of wine’s characteristics.

High quality wines start in the vineyard however little is known about the role vineyard management practices play in this quality outcome. Gold medals and well-known regionality increase consumer preference for purchasing a wine. An increase in the former will certainly also drive an increase in the latter and therefore practices in production that consistently lead to gold medal winning wines will improve both the marketability of the region and its products. It is argued that vinification is the main driver of wine quality and in fact, the presence of some oak compounds is a well-known consumer and expert mark of quality. However, only select wines are vinified in oak and therefore the original grape quality at the winery door must in fact drive all further downstream vinification decisions.

Climate change and harvest date decisions have led to the evolution of must quality over the last decades. Increases in must sugar concentrations are among the most obvious consequences, quantitatively. Saccharomyces cerevisiae is a robust and acid tolerant organism. These properties, its sugar to ethanol conversion rate and ethanol tolerance make it the ideal production organism for wine fermentations. Unfortunately, high sugar concentrations may affect S. cerevisiae and lead to growth inhibition or yeast lysis, and cause sluggish or stuck fermentations. Even sublethal conditions cause a hyperosmotic stress response in S. cerevisiae which leads to increased formation of fermentation by-products, including acetic acid, which may exceed legal limits in some wines.

With the development of naturality expectations, wines produced without any addition of sulfur dioxide (SO₂) become very popular for consumers and such wines are increasingly present on the market. Recent studies also showed that Bordeaux red wines without added SO₂ could be differentiated from a sensory point of view from similar wines produced with SO₂¹. Thus, the aim of the current study was to characterize from a sensory point of view, specific aromas of wines without added SO₂ and to identify compounds involved.

Climate change leads to even more hostile and stressful for the wine microorganism conditions and consequently issues with fermentation rate progression and off-character formation are frequently observed. The objective of the current research was to classify a great collection of yeast isolates from Greek wines based on their technological properties with oenological interest. Towards this direction, fourteen spontaneously fermented wines from different regions of Greece were collected for further yeast typing. The yeast isolates were subjected in molecular analyses and identification at species level.