Assessment of Potential Side 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, inorganic ion exchangers among other substances, essentially used to control the amount of wine phenolics, but have also 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 side effects on wine protein haze forming potential, as well as on the levels of proteins and phenolic compounds in a Muscat of Alexandria wine. Bentonite was selected as the positive control, whereas non-fined wine was used as the negative control. Differential results were detected among the selected fining agents when compared to the controls. Thus, 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 are second to bentonite in removing the highest amount of 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 a larger polyphenol amount while leaving its haze forming potential unaltered. The fining agents analyzed did not significantly affect the wine protein content, but removed considerable amounts of polyphenols and presented no apparent effect on protein stabilization of the fined wines. Thus, our data show that these fining agents do not contribute in a significant way to guarantee protein stabilization in white wines, confirming that bentonite remains the most effective agent in wine protein stabilization.