OTR determination of aged closures: Impact on aroma compounds composition of Sauvignon blanc wines

The need to combine multimodal data for complex samples is due to the different information captured in each of the techniques (modes).

In a recent study several genes controlling the acidification properties of the wine yeast Saccharomyces cerevisiae have been identified by a QTL approach [1]. Many of these genes showed allelic variations that affect the metabolism of malic acid and the pH homeostasis during the alcoholic fermentation. Such alleles have been used for driving genetic selection of new S. cerevisiae starters that may conversely acidify or deacidify the wine by producing or consuming large amount of malic acid [2]. This particular feature drastically modulates the final pH of wine with difference of 0.5 units between the two groups.

AIM The main lead exposure route is the intake of contaminated food, water, and alcoholic beverages, in particular wine. At the gastric level, Pb is transformed into a soluble compound which, when conveyed into the bloodstream, is the long-term cause of saturnism, intoxication with neurotoxic, nephrotoxic and hematopoietic effects, and with the neurological developmental delay of children. Pb is classified by the International Agency for Research on Cancer as a 2A class, possible carcinogenic to humans. In an opinion on possible health risks, CONTAM considered that cereals, vegetables, drinking water, and wine give a greater contribute to dietary exposure to Pb in Europe. Large quantities of wine, beer, and other alcoholic products drinking can increase daily Pb intake above the maximum permitted levels.

Sotolon (3-hydroxy-4,5-dimethyl-2(5H)-furanone) is a naturally occurring odorant compound with a strong caramel/spice-like scent, present in many foodstuffs. Its positive contribution for the aroma of different fortified wines such as Madeira, Port and Sherry is recognized. In contrast, it is also known to be responsible for the off-flavor character of prematurely aged dry white wines. The formation mechanisms of sotolon in wine are still not well elucidated, particularly in Madeira wines, which are submitted to thermal processing during its traditional ageing. The sotolon formation in these wines has been related to sugar degradation mechanisms, particularly from fructose [1].

Following anecdotal evidence of unwanted ‘tropical’ character in red wines resulting from vineyard interventions and a subsequent yeast trial observing higher ‘red fruit’ character correlated with higher thiol concentrations, the role of polyfunctional thiols in commercial Australian red wines was investigated.
First, trials into the known tropical thiol modulation technique of foliar applications of sulfur and urea were conducted in parallel on Chardonnay and Shiraz.1 The Chardonnay wines showed expected results with elevated concentrations of 3-sulfanylhexanol (3-SH) and 3-sulfanylhexyl acetate (3-SHA), whereas the Shiraz wines lacked 3-SHA. Furthermore, the Shiraz wines were described as ‘drain’ (known as ‘reductive’ aroma character) during sensory evaluation although they did not contain thiols traditionally associated with ‘reductive’ thiols (H2S, methanethiol etc.).