Fining strategies for quercetin deposit prevention in sangiovese wines

A strategy aimed at decreasing the content of quercetin (Q) and quercetin glycosides (QG) was applied to prevent future quercetin precipitation in wines. Different oenological fining agents were tested: polyvinylpolypyrrolidone (PVPP), a vegetable protein (VP), four yeast lysate (YLs) and a polyfunctional product (MIX) obtained by mixing PVPP, vegetable protein and a yeast lysate selected among the four tested. For each fining agent the adsorption isotherms were obtained; based on Freundlich model, PVPP and MIX showed the best adsorption of Q and QG. The MIX determined also a contemporary lower adsorption of other phenolic compounds. The treatment carried out with MIX on the Sangiovese wines determined a decrease of Q (from −27 to −47% with respect to the initial values) and of QG (−17%) preserving wine anthocyanins.