Caratterizzazione della componente volatile di vini bianchi privi di solfiti ottenuti dopo fermentazione in presenza di chitosano

Oxidation of wine is one of the main problems to be faced by winemakers during vinification due to the alteration of both phenolic and volatile compounds. Particularly, in white wines, oxidation leads to a decrease of the overall attractiveness of final products. Volatile compound are deeply involved in the oxidative decay of wines, being reduced the aromatic character due to the loose of grape-derived odoriferous compounds. Among all the preservatives used in oenology sulphur dioxide has demonstrated to possess the most powerfull antioxidant and antimicrobial properties, controlling undesirable fermentations and preventing from oxidative spoilage in white and red wines (Ribereau-Gayon et al., 2006). However, its use has been questioned due to the adverse effect to the human health, causing asthma, dermatitis, bronchoconstriction, urticaria or anaphylaxis. Due to the disadvantages, substitution or reduction of the employment of sulphur dioxide in wine is one of the objectives pursued by winemakers. Despite all the efforts made to replace sulphur dioxide in wines, including physical, chemical or biological treatments, none of them has demonstrated enough effectiveness to completely substitute sulphur dioxide so a decisive alternative to sulphites is still unknown. Chitosan is the deacetylated product of chitin, a homopolymer of n-acetyl-glucosamine, extracted from shell, insects of fungal sources. Its features like metal chelation, multifaceted antioxidant and radical scavenging activities against hydroxyl and superoxide radicals makes this natural products very attractive to use in food and agriculture sciences. Recently, the use of chitosan has been authorized in must and wine for microbial stabilization, or metal and protein removal (Commission regulation EU 53, 2011) but its use as an antioxidant is still scarcely studied. The aim of this work was to study the effects of the fermentative addition of chitosan on fixed and volatile compounds of sulphites free white wines. Studies of the difference between sulphite-free white wines and those added with sulphur dioxide in fermented must and after 12 months of storage were carried out.