Bentonite has been used for several decades in winemaking to improve the clarity and stability of wine and to prevent the formation of deposits in the bottle. The exchangeable cations in its lamellar structure influence certain properties such as: specific surface area, ion exchange, swelling index and, consequently, protein removal capacity, adsorption or interaction with phenolic substances and aromas.

As with any adjuvant and additive, the use of bentonite, without specific knowledge, both for must clarification and wine stabilization, can compromise colloidal and protein stability, phenolic compounds and aroma, and the sensory profile of the wine.

The interaction of bentonite with turbidity-forming proteins (PRP) varies according to the characteristics of the bentonite and the different classes of proteins (glucanase, chitinase, thaumatin, invertase) and is influenced by pH, ionic strength, sulfite content, presence of glycosylated proteins released by yeast, etc.

On the other hand, the thermal resilience of bentonite-stabilized wine and the possible impact on its sensory profile due to the undesired elimination of aromatic molecules depends on other factors, such as the presence of natural wine protective colloids, chemicals and oxidation. -The reductive characteristics of the volatile molecules, as well as their degree of inclusion in the colloidal matrix of the wine.

In addition, special care must be taken in the treatment of aromatic grape musts and wines to maximize the removal of PRP while minimizing the removal of aroma precursors and related active olfactory molecules.

Finally, more interest is given to the stabilization of PRP in rosé wines that normally require various fining interventions with bentonite, without significant impact on the concentration of anthocyanins that characterize the color of the wines themselves.

This session at Enoforum 2024 will illustrate all these aspects examined in the context of numerous experimental tests aimed at controlling the effects of bentonite and obtaining applicable and reliable results for the winemaker.