Abstract:
The presence of proteins in wine is associated with instability risks, often manifesting as spontaneous turbidity during storage and commercialization. Conventional methods for evaluating protein instability, such as thermal shocks or chemical reactions with gelatin and tannins, combined with turbidity measurements, do not offer a thorough assessment of wine stability. This complexity is attributed to several factors, which can be classified into two primary categories: intrinsic factors related to the wine's composition, and extrinsic factors linked to processing and storage conditions. Only a small subset of proteins in wine exhibit thermal instability, typically those with molecular weights around 24-32 kDa. Interactions between proteins and other components in wine can either stabilize or destabilize protein colloids, leading to sedimentation. Moreover, proteins can affect the accuracy of analytical measurements of phenolic compounds. Specifically, they may interfere with the Folin-Ciocalteu reagent, which is used to quantify polyphenols, by influencing the ultraviolet range (260-280 nm) spectrophotometrically, thus distorting the results.
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