The fining is an important step in oenology; it clears the wine and reduces astringency. A better understanding of the effect of proteins of fining, specifically gelatines on phenol will allow for better techniques of fining. As well it will give direction to research new proteins that could be substituted for gelatines like with vegetable proteins. The phenological composition of 5 wines were studied before and after the fining with 2 gelatines of the same and different molecular weights(16 kD and 190 kD) with 3 vegetable proteins. The gelatines precipitated the same quantities of tannins (ƒ° 15%) but the quality was different. The gelatine that was the most hydrolysis (16 kD) eliminated a higher degree of polymerisation of tannins than the gelatine less hydrolysis (190 kD). Sensory analysis of wines shows that lower levels of astringency are linked to the lower levels of condense tannins (plus or minus polymerised) and/with with the elimination of high levels of polymerisation with strong polymerisation and galloype tannins. For the gelatines, the vegetable proteins eliminated lower quantities of tannins but the quality stayed the same. These results indicate that vegetable proteins can be used as fining products.
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