Assessment of Potential Effects of Common Fining Agents Used for White Wine Protein Stabilization

Abstract

A variety of fining agents are commercially available to the wine industry, including proteins and inorganic ion exchangers. These fining agents are essentially used to control the levels of phenolics in wine, but they also have the potential to interact with other wine components, most often as a side effect. They are therefore expected to influence, at least in part, the potential for wine protein haze formation. Six common fining agents—casein, egg albumin, isinglass, chitosan, chitin, and polyvinylpolypyrrolidone (PVPP)—were analyzed to assess their effects on wine protein haze-forming potential and on the levels of proteins and phenolic compounds in a Muscat of Alexandria wine. Bentonite was selected as the positive control, whereas nonfined wine was used as the negative control. Differential results were detected among the selected fining agents when compared to the controls. Egg albumin and chitosan, although incapable of stabilizing the wine, originated a small but significant decrease in the protein haze formed, whereas chitosan and PVPP were second to bentonite in removing the most polyphenols from the wine. Thus, while chitosan fining removes a fraction of polyphenols from the wine and seems to induce a small decrease in its haze-forming potential, PVPP eliminates more polyphenols while leaving its haze-forming potential unaltered. The fining agents analyzed did not significantly affect wine protein content but did remove considerable levels of polyphenols and presented no apparent effect on protein stabilization of the fined wines. Results show that these fining agents do not contribute significantly to protein stabilization in white wines, confirming that bentonite was the most effective agent in wine protein stabilization.