OENO One (Mar 2021)
REDUCING SO2 CONTENT IN WINE BY COMBINING HIGH PRESSURE AND GLUTATHIONE ADDITION
Abstract
The aim of this work was to examine the potential of High Pressure (HP) technology as an alternative technique for red wine preservation, focusing on the production of reduced SO2 wines while simultaneously adding glutathione (GSH), as a natural antioxidant. Selected quality parameters of red wine samples from Mouchtaro grapes, treated by HP under various pressure parameters were tested. HP processing studied was applied at 200, 400 and 600 MPa for 0, 5 and 15 minutes. Application of HP for high duration resulted in significant reduction of phenolic compounds concentrations (TP) due to extended polymerization and simultaneously at reduced volatile acidity (VA) and acetic acid concentrations (AAC) mainly due to better antimicrobial protection. Based on the alterations in the contents of all groups of TPs, VA and AAC, processing for 5 min at 400MPa was selected as the optimum HP condition. Red wine samples from Mouchtaro grapes containing 0, 20, 40, 60, 80 and 100 mg/L of SO2 and 10 mg/L of GSH were HP treated under the selected pressure/time conditions. Another group of untreated samples containing the same concentrations of SO2 and GSH was used as control samples. Indices such as AAC, Antioxidant activity (AOA), total anthocyanins, TP, mean Degree of Tannin Polymerization (mDP) and volatiles composition were determined over a period of 12 months. Sensory analysis of the samples took place during the 12th month of storage. After the period of twelve months, pressurized samples with GSH presented higher content of total aldehyde/ketone and higher-alcohols and consistently lower concentrations of acetic acid, ethyl acetate, total esters and lower values of VA. Finally, based on the results obtained by the sensory analysis, untreated samples were characterized by "Red fruits" odours, whereas treated samples were distinguished based on their "chocolate" aroma. These results suggest that HP could be used for the production of more "mature" wines. Reduced SO2 concentration up to 40 or 60 mg/L could be sufficient for wine stabilization combining HP treatment and GSH additions, depending on grape variety.
