The use of viticultural and oenological performance of grapevines to identify terroirs: the example of Sauvignon blanc in Stellenbosch

One of the main effects of global warming is an increase in the sugar concentration of grapes at harvest time, resulting in wines with a high alcohol content and an unbalanced structure. The fruit to leaf ratio is a key factor in determining the final sugar concentration, and training systems and management techniques can help to control this parameter.

Polyphenolic compounds are considered to have a major impact on the quality of red wines. Sensory impact, such as astringency and bitterness, stems directly from tannin composition. Thenceforth, quick analytical measurement of phenolic compounds appears to be a real challenge for winemaking monitoring and process control. Many methods were developed to analyzed polyphenols in wine, but they are time-consuming and require chemistry skills and equipment, not suitable for a rapid routine analysis. A reliable and rapid method to obtain this kind of measurement is Fourier Transform Infrared (FTIR) spectroscopy.

Climate change increasingly leads to altered growing conditions in viticulture, such as heat stress, drought or high infection pressure favoring pathogen infection.

Vineyards harbor a myriad of microorganisms that interact with each other and with the grapevines. Some microorganisms are plant pathogens, such as the oomycete Plasmopara viticola that causes grapevine downy mildew. Others, such as plant growth promoting bacteria and disease biocontrol agents, have a positive influence on vine health. The present study aims to (1) investigate whether vine-based culture media increase the cultivability of the grapevine microbiota, in comparison to standard culture media and (2) identify and isolate bacterial taxa naturally present in grapevine leaves and significantly more abundant in plots showing low susceptibility to downy mildew.

AIM Astringency is described as a ‘dry puckering‐like sensation’ following consumption of tannins1 that affect consumer preference of foods and beverages, including red wine2. To improve the understanding of astringency, which is a complex interaction due to multiple mechanisms occurring simultaneously, further studies are needed. In this view, oral tribology is considered a useful technique for beverage study to evaluate the thin-film lubrication properties of saliva resulting in oral friction‐related sensations3. The aim of this study was to examine the film behavior of selected protein-based fluids under controlled friction conditions, to understand polyphenol-protein interactions involved in the sensation of astringency.