IVES 9 IVES Conference Series 9 OENO IVAS 9 OENO IVAS 2019 9 Category: Chemical and Biochemical reactions, including grape and wines microorganisms impact

Chemical and Biochemical reactions, including grape and wines microorganisms impact

Chemical and Biochemical reactions, including grape and wines microorganisms impactIVES Conference SeriesOENO IVAS 2019

Fructose implication in the Sotolon formation in fortified wines: preliminary results

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].

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Chemical and Biochemical reactions, including grape and wines microorganisms impactIVES Conference SeriesOENO IVAS 2019

Varietal differences between Shiraz and Cabernet sauvignon wines revealed by yeast metabolism

This study investigated if compositional differences between Shiraz and Cabernet Sauvignon grape varieties could influence the production of yeast-derived compounds. This work was based on the analysis of 40 experimental red wines made in triplicate fermentations from grapes harvested from two consecutive vintages in New South Wales (Australia). Grapes were picked at three maturity stages using berry sugar accumulation as physiological indicator, from nine commercial vineyards located in three different climatic regions (temperate, temperate-warm and warm-hot). A range of 30 yeast-derived wine volatiles including esters and alcohols were quantified by HS/SPME-GC/MS. Ammonia, amino-acids and lipids were analysed in the corresponding grapes. The juice total soluble solids (°Brix) in addition to the wine alcohol and residual sugar levels were also measured. The influence of grape maturity on wine ester composition was also variety dependent, particularly for higher alcohol acetate and ethyl ester of branched acids. This study highlights that varietal differences observed in Shiraz and Cabernet Sauvignon wines involve fermentation-derived compounds irrespective of the site (soil, climate, viticultural practices).

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Chemical and Biochemical reactions, including grape and wines microorganisms impactIVES Conference SeriesOENO IVAS 2019

When organic chemistry contributes to the understanding of metabolism mechanisms

Many compounds of interest in wine are difficult to analyze since they are present in very small quantities or they are unstable. The need for reliable data led scientists to develop complex method in order to overcome the analytical difficulties and provide accurate quantitative data for grape or wine characterization.

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