Novel analytical technologies for wine fingerprinting in and beyond the laboratory

Volatile thiols contribute largely to the organoleptic characteristics and typicity of Sauvignon blanc wines. Among this family of odorous compounds, 3-sulfanylhexan-1-ol (3SH) and 4-methyl-4-sulfanylpentan-2-one (4MSP) have a major impact on wine flavor. These thiols are formed during alcoholic fermentation by the yeast from odorless and non-volatile precursors found in the berry and the must. The effect of vine nitrogen status on 3SH and 4MSP in Sauvignon blanc wine and on the glutathionylated and cysteinylated precursors of 3SH (Glut-3SH and Cys-3SH) was investigated in this study.

Wine is a solution containing abundant volatile compounds which contribute to their aroma. Many of them are produced by yeast as metabolism by-products. Different yeast strains produce different volatile profiles. The possibility of studying the evolution of volatile compounds during fermentation, using sampling methods that not alter the volume of fermentation media, is of great interest. In spite of this, non-invasive methods to monitoring the evolution of volatile profile during fermentation have been seldom used. The goals of this work were to use by first time the headspace sorptive extraction (HSSE) as non-invasive method to monitor the evolution of volatile profiles throughout alcoholic fermentation and to study the changes on volatile profiles produced by Saccharomyces cerevisiae and Lachancea thermotolerans during fermentation of a must with high sugar content.

The impact of minute amounts of headspace oxygen on the post-bottling development of wine is generally considered to be very important, since oxygen, packaging and storage conditions can either damage or improve wine quality. This is reflected in the generalised use of inert bottling lines, where the headspace between the white wine and the stopper is filled with an inert gas. This experiment aimed to address some open questions about the chemistry of the interaction between wine and oxygen, crucial for decisions regarding optimal closure. While it is known that similar amounts of oxygen affect different wines to a variable extent, our knowledge of chemistry is not sufficient to construct a predictive method.

Fining is a technique that is used to remove unwanted wine components that affect clarification, astringency, color, bitterness, and aroma. Fining involves the addition of adsorptive or reactive material in order to reduce or eliminate the presence of certain less desirable wine components and to ensure that a wine remains in a particular stable state for a given period of time Recently concerns have been raised about the addition of animal proteins, such as gelatin, to wine due to the disease known as bovine spongiform encephalopathy (Mad Cow disease). Although the origin of gelatins has been moved to porcine, winemakers are asking for substitute products with properties and application protocols similar to the traditional animal-derived ones, making the use of plant-derived proteins in fining a practically viable possibility. As a consequence, various fining agents derived from plants have been proposed, including proteins from cereals, legumes, and potato.

Sorting Chenin blanc is one of the most important white wine cultivars in South Africa. It has received a lot of attention and accolades in the past years and more research than ever is dedicated to this versatile cultivar. According to the Chenin blanc association of South Africa, there are three recognized dry wine styles, Fresh and Fruity (FF), Rich and Ripe Unwooded
(RRU), and Rich and Ripe Wooded (RRW). They are traditionally established with the aid of expert sensory evaluation, but the cost and the (subjective) human factor are aspects to be taken into account. A more objective and possibly robust way of assessing and attributing these styles can be the use of chemical analysis.