Effects of the pre‐fermentative addition of chitosan on the nitrogenous fraction and the secondary fermentation products of SO₂‐free red wines

BACKGROUND Different red winemaking were carried out to evaluate the effects of the prefermentative addition of chitosan, as an alternative to the use of SO 2 , on the secondary products of alcoholic fermentation, yeast available nitrogen (YAN), biogenic amines and ethyl carbamate. RESULTS The wines made with chitosan presented higher total acidity and higher content of tartaric and succinic acids than those made only with SO 2 . The use of chitosan in winemaking resulted in wines with higher glycerol and diacetyl content without increasing the concentration of ethanol, acetic acid, acetaldehyde or butanediol. YAN was lower in wines made with chitosan, which may mean an advantage for the microbial stability of the wines. Furthermore, the use of chitosan at the beginning of alcoholic fermentation did not increase the concentration of biogenic amines or the formation of ethyl carbamate in SO 2 ‐free red wines. CONCLUSION The total or partial substitution of SO 2 for chitosan at the beginning of the alcoholic fermentation gives rise to quality red wines without negatively affecting their nitrogen fraction or their very important secondary fermentation products such as acetic acid or acetaldehyde.