The effect of bentonite fining at different stages of white winemaking on protein stability

Background and Aims: Bentonite fining to remove protein is the most widely used treatment to prevent protein haze in white wines. Bentonite can be added at different stages during winemaking. This study aimed to determine the best time to add bentonite. Methods and Results: Unstable juices were vinified after bentonite fining of juice, or with bentonite added either early or late in fermentation. Different addition rates of bentonite were used and bentonite was either added in one or two additions. Fermentation rates were observed and protein stability and bentonite fining rates of the resultant wines were determined. Conclusions: Adding bentonite during fermentation or fining finished wines was the most efficient option in terms of amounts of bentonite required. Fermenting with bentonite present also may increase fermentation rates. Significance of the Study: Using the least bentonite necessary for heat stability is important for winemakers for quality, cost and environmental reasons. This study describes ways in which bentonite addition rates can be minimised.