Impact of fining agents on Swiss Pinot noir red wines

Abstract

In the context of climate change, excessive bitterness and astringency in wines have become increasingly prevalent. While variety selection and viticultural practices offer long-term solutions, they require considerable time before yielding practical results. In contrast, fining remains an accessible and immediate tool for winemakers. However, many experienced wine professionals still struggle to fully understand the effects of different fining agents on their wines. Additionally, with new European regulations on wine labeling, there is an urgent need to better comprehend the mechanisms of different fining agents across various wine matrices to ensure informed decision-making in cellar.

Fining is a technique commonly used in winemaking to correct the levels of bitterness and astringency in wines. Various fining agents are employed for this purpose, such as gelatin, egg whites, pea protein, potato protein, casein, etc. Studies in this field have shown that each fining agent has a very different impact on the characteristics of the wine, and their effects also depend on the specific composition of the wine [1-3]. To our knowledge, no study in the literature has reported the impact of different fining agents on Pinot Noir wines.

This study evaluated the impact of four commercial fining agents: gelatin, egg albumin, pea protein, and potato protein, on the phenolic composition and sensory properties of two Pinot Noir wines. At the lowest recommended dosage, gelatin was the most effective in reducing total phenolic compounds, condensed tannins, mean degree of polymerization (mDP), yellowness and astringency. Notably, this is the first study demonstrating that mDP in Pinot Noir wines is significantly affected by fining. Pea protein proved to be the most efficient in reducing bitterness, aligning with empirical observations from Swiss Pinot Noir producers. Our results further highlight the significant influence of phenolic richness and maturation stage on the effectiveness of fining. Wines with lower phenolic content were more strongly affected, emphasizing the need for a tailored approach based on wine composition and aging stage. Additionally, the observed reduction in yellowness suggests that oxidized pigments were partially removed during fining. These findings underscore the importance of carefully selecting fining agents and adjusting their dosages according to the maturation stage and the desired wine style, particularly for delicate varieties such as Pinot Noir.

References

[1] González-Neves, G., G. Favre, and G. Gil, Effect of fining on the colour and pigment composition of young red wines. Food Chem., 2014. 157: p. 385-392.

[2] Fernanda, C., M.R.-d.-S. Jorge, and L. Olga, Effect of various proteins on different molecular weight proanthocyanidin fractions of red wine during wine fining. Am. J. Enol. Vitic., 2009. 60(1): p. 74.

[3] Río Segade, S., et al. Phenolic composition influences the effectiveness of fining agents in vegan-friendly red wine production. Molecules, 2020. 25, DOI: 10.3390/molecules25010120.