Wine-making with protection of must against oxidation in a warm, semi-arid terroir

Abstract

In order to defend varietal aromas from oxidation before alcoholic fermentation, two musts were prepared from white grapes pre-cooled and added with ascorbic acid and solid CO2 (trial ACO2) or SO2 (trial BSO2). Experiments were performed with grapes of a white grape variety indigenous to western Sicily, the wines from which, obtained by vinification of musts protected from oxidation and poor in copper, as previously proven, have aroma descriptors ascribed to passion fruit and grapefruit skin. The smaller content in flavanols in the ACO2 trial, demonstrated that the use of solid CO2, instead of SO2, reduced the extraction of such polyphenols from grape solids. The higher content in hydroxycinnamoyl tartaric acids of the wine from ACO2 trial with respect to BSO2 was ascribed to the minor grape polyphenol-oxidase activity induced by the loss of oxygen stripped by CO2 in ACO2 or to the combination of caftaric acid quinone to the SO2 in BSO2. Although the grapes were very ripe (alcohol in wines ~ 14.5% vol), wines made with musts prepared by the two techniques were characterised by aroma descriptors like passion fruit and grapefruit skin not detected in wines prepared from musts not protected from enzymatic oxidations.