Olfactometry approach to assess odorant compounds of grape spirits used for Port wine production-first results

Glutathione is a natural tripeptide composed of l-glutamate, l-cysteine and glycine, found in various foods and beverages. In particular, glutathione can be found in its reduced (GSH) or oxidized form (GSSG) in must, wine or yeasts¹. Numerous studies have highlighted the importance of GSH in wine quality and aging potential². During winemaking, especially during aging on lees, GSH helps prevent the harmful effects of oxidation on the aroma of the wine³. Nevertheless, the amounts of GSH/GSSG present in wine lees are often unknown and the choice of operating conditions (quantity of lees and aging time) remains empirical.

The mineral composition of wine spirit (WS) is of relevant interest due to its potential effect on physicochemical stability, sensory characteristics, and safety.1 Calcium (Ca) and iron (Fe) can form insoluble compounds, negatively affecting the WS clarity. Transition metals, e.g. Fe and copper (Cu), seem to play an important catalytic role on oxidation reactions involving phenolic compounds and other substrates for oxidation in WS

The wine industry currently relies on a limited number of grapevine cultivars, comprised of numerous clones with slight differences in their viticultural, oenological, or stress-tolerance traits.

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.

Sulfur dioxide is the most commonly used additive in oenology to protect wine from oxidation and microorganisms. Once added to wine SO2 is able to react with carbonyl compounds to form carbonyl bisulfites what affects their reactivity.