Limit SO2 content of wines by applying High Hydrostatic Pressure

Sulphur dioxide (SO2) has an important role in wine industry as an antioxidant, antioxidasic and antiseptic additive. However, since SO2 is also responsible for allergic reactions, it is of great interest its replacement with alternative additives or technologies. The potential use of High Pressure (HHP) as an alternative antimicrobial technique to preserve wine with reduced amounts of SO2 was explored in this study. Red wine samples containing 0, 30, 60 and 100 mg/L total sulphur dioxide (SO2) were subjected to pressure treatment at 350 MPa for 10 min at 8 degrees C. Another group of non-treated samples containing similar amounts of SO2 was used as control. Color parameters, total flavanols and antioxidant activity were determined by spectrophotometry while for individual anthocyanin content and tannin structural characteristics HPLC and HPLC/MS were employed respectively. Analyses were initially performed every two months (up to 6 months of storage) and thereafter at 12 months. Sensory analysis was also performed at the end of storage period by a trained panel. Pressurised wines with <60 mg/L SO2 showed reduced total flavanols, anthocyanins and antioxidant activity values and higher hue after six months of storage when compared to the non-treated samples. These results were in line with the sensory evaluation of the treated samples, perceived as less aromatic, more oxidized and with higher intensity of dried fruit odor. However, after twelve months of storage these differences between the non-pressurised and pressurised wines, which contained over 60 mg/L SO2, were not significant indicating that HHP could potentially preserve wine when combined with addition of reduced contents of SO2. Industrial relevance: Since SO2 is a cheap and effective wine preservative; its complete replacement seems not feasible at the moment. However, a more realistic approach is the reduction of the quantities required for wine protection and preservation by combining the antimicrobial action of the HHP process and the antioxidant effect of Sulphur Dioxide. This work shows that HHP can potentially be employed in winemaking to complement the action of SO2 making thus possible to reduce the required doses in wine.