Effectiveness of chitosan as an alternative to sulfites in red wine production

Part of sulfur dioxide used to preserve wine reacts with several wine compounds and it is not anymore active and capable of performing its antioxidant and antiseptic functions. In this work, with the aim to decrease the amount of SO2-bound to acetaldehyde, the use of chitosan in pre and post fermentative phases during the production of Aglianico red wine was investigated. Two winemaking batches, one made of 100% of healthy grapes and one composed of 50% healthy grapes and 50% berries damaged by acid rot, were considered. Results highlight that the use of chitosan just after the end of the fermentation allowed a lower production of SO2-bound to acetaldehyde in finished wines. Furthermore, when chitosan was used in post-fermentative phases, a higher content of polymeric pigments and a lower content of tannins reactive towards proteins was observed. All these effects were less evident when partially acid rot contaminated grapes were used.