Effects of verjus acidification on muscat canelli grape juice and wines

Abstract

Our study aimed to investigate the use of verjus (green grape juice) as an acidifying agentfor improving the overall acid profile and balance of wine, lowering the pH and alcohol content and creating a sustainable winemaking practice that can be utilised in warm grape-growing regions, such as Texas, where pH levels range from 3.5 to over 4.0 in white juice and wine. Muscat Canelli wines were produced using two different treatments for pH and acidity balance. Verjus was produced by pressing under-ripe grapes resulting from crop thinning practices and added at two different rates of 2 % and 11 % to juice obtained from ripe grapes prior to fermentation. For all the wines produced, pH, titratable acidity (expressed as g/L Tartaric Acid), alcohol, glucose-fructose, l-malic acid, tartaric acid, potassium, polyphenols were analysed, and preference testing was performed via consumer sensory panels. Results obtained indicate that verjus can be used to balance pH and acidity as well as lower alcohol content. Consumer preference ranking indicated no significant differences between any of the treatments, while acidity rankings correctly distinguished the wines according to their acid levels. This work shows that the use of verjus as a pre-fermentation acidification agent could be a potential tool for winemaking to help mitigate the negative effects associated with climate change.