Influence of bentonite fining on the composition and quality of white wine

Zamućenje bijelog vina nastaje zbog narušene proteinske stabilnosti vina, a sprječava se bistrenjem bentonitom, koji je najčešće korišteno bistrilo zbog prednosti stabilizacije vina djelovanjem na proteine. Najnestabilniji proteini bijelih vina su TL-proteini, hitinaze i ß-glukanaze, koji stvaraju zamućenje i u malim koncentracijama, a na bentonit se vežu elektrostatskom adsorpcijom i talože. Bistrenje bentonitom može dovesti do gubitaka vina te indirektnog uklanjanja poželjnih spojeva koji čine sortnu i fermentativnu aromu vina. Bentonit se može dodati u različitim fazama fermentacije, međutim, ustanovljeno je da je najučinkovitije bistrenje vina pred kraj fermentacije gdje je potrebna količina bentonita manja u odnosu na druge faze fermentacije te se stvara manje taloga. Također, natrijev bentonit ima veću moć adsorpcije proteina u odnosu na njegov aktivirani oblik, iako aktivirani natrijev bentonit daje manje taloga. Bentonit se primjenjuje šaržno uz njegovo prirodno taloženje, međutim, istražuju se nove metode kontinuiranog in-line doziranja bentonita kojim se smanjuje gubitak vina.Turbidity of white wine occurs due to disrupted protein stability of wine and is prevented by clarification with bentonite, which is the most commonly used clarifier due to the benefits of stabilizing wine by acting on proteins. The most unstable proteins of white wines are TL-proteins, chitinases and ß-glucanases, which create turbidity even in small concentrations, and bind to bentonite by electrostatic adsorption with precipitation. Bentonite clarification can lead to wine losses and indirect removal of desirable compounds that make up the varietal and fermentative aroma of the wine. Bentonite can be added at different stages of fermentation, however, it was found that the most efficient clarification of wine is before the end of fermentation where the required amount of bentonite is lower, compared to the other stages of fermentation and less sediment is formed. Also, sodium bentonite has a higher protein adsorption power compared to its activated form, although activated sodium bentonite yields less sediment. Bentonite is applied batch-wise with its natural precipitation, however, new methods of continuous in-line dosing of bentonite to reduce wine loss are being investigated