Gamay and Gamaret winemaking processes using stems: impact on the wine chemical and organoleptic characteristics

Abstract

AIM: Stalks are empirically known to bring many benefits to the wine such as alcoholic reduction, color protection or improvement of the tannic intensity. Not much used on Swiss grape varieties, the aim of this study was to identify the relevance of using this type of winemaking in the case of Gamay and Gamaret red grape varieties.

METHODS: Gamay and Gamaret grapes from a vineyards in Gland (Switzerland) were harvested and treated according to three modalities: fully destemmed used as control, 20% and 40% either whole grapes or stems added to the rest of the destemmed harvest. The influence of the stalks on the wine organoleptic properties was measured using different classical FTIR and colorimetric methods (alcohol, acidity, pH, SO2 …). Polyphenol content was evaluated using spectrophotometer measurements and concentration of flavanols and proanthocyanins in wine samples determined by HPLC-FLD-MS/MS. Sensory analysis were also performed in order to measure the impact on the wines.

RESULTS: Results showed that the total polyphenolic content was lower for trials with non-destemmed grapes and higher for the ones where stems were added. According to the tannin content, no significant differences were found between the modalities for the gamay grape variety. For the gamaret grape variety, the values were lower than the control when 20% and 40% of non-destemmed grapes were used. Planned sensory analysis should allow us to know the impact on the aromatic characters of these wines.

CONCLUSIONS:

This study allows us to acquire knowledge about winemaking processes performed using non-destemmed grapes and their impact on the wine characteristics. Both chemical composition and organoleptic characterization were taken into account