As a winemaker working in a world where many consumers base their purchases off of looks alone, the right colour and clarity of your product can make or break your brand. Several steps are required to transform grapes off the vine to the crystal clear wines found on the shelves of Australia. Before shipping to the local market, wine is treated with fining agents, since unrefined wine is quite turbid and hazy. The turbidity is due to suspended solids produced during fermentation. This cloudiness is what winemakers refer to as protein haze, or haze for short. Thaumatin-like proteins (TLPs) and chitinases are the primary grape proteins responsible for haze formation. These positively charged proteins degenerate and stick together, resulting in undesirable flocculent clouds and visible haziness. Bentonite clay is used as a fining agent in wine.

Fining, or clarifying, is the process of removing substances that contribute to haze by binding them through adsorption. Bentonite is negatively charged and incorporated into the wine as a colloid (fine powder mixed with water). The negatively charged clay binds to the positively charged protein molecules. After treating the wine, the particulates settle out, transforming the beverage to the desired colour and clarity. This process also makes the wine more stable, meaning the wine’s signature taste, aroma and appearance won’t change appreciably while in storage.