Reduction of Red Wine Astringency Perception Using Vegetable Protein Fining Agents

The use of vegetable proteins to fine astringent compounds in wine has gained increased interest due to the pressure of consumer demand. The objective of this study was to compare the ability of alternative vegetable proteins (derived from rice, soy, pea, or potato) to reduce tannin and thereby astringency, relative to that of traditional fining agents (gelatin and polyvinylpolypyrrolidone [PVPP]) in a commercial wine with added grape seed extract. Total tannin and phenolics, SO₂-resistant pigments, pH, and color of the treated wines were determined, and astringency intensity perception was evaluated by a trained sensory panel (n = 9). Potato, pea, soy, and gelatin proteins similarly reduced total tannin concentration. Similar to PVPP, addition of rice or soy protein reduced total phenolics. These alternative vegetable proteins also influenced the chroma, which may change the depth of wine color. Furthermore, this study was the first to evaluate the change in astringency sensation resulting from the use of rice and soy proteins as alternative fining agents. The type of vegetable proteins used appeared to fine different types of polyphenolic compounds, an observation that was reflected on astringency perception and requires further investigation. The chemical and sensory measures showed that rice and potato proteins have the potential to replace PVPP and gelatin, respectively.