Bentonite: Application in wine production and impact on wine quality. A review of the scientific literature

Abstract

Bentonite has been widely used in wine industry over a few decades. The main purpose of using bentonite as a fining agent is to remove the excess proteins remained in wine as potential protein haze formation in white wine is of great concern for winemakers. The resulting cloudiness in wine is usually considered as wine fault. Thus, protein stabilization before bottling is critical for white wine production, particularly for some varietals with high protein content such as Sauvignon Blanc. However, bentonite is not specific to absorb proteins, the addition of bentonite into juice or wine may cause the loss of other juice/wine compounds such as aroma and flavour compounds. Moreover, large dosage of bentonite addition could also result in loss of wine volume as wine lees. Thus, some alternative methods are proposed by researchers aiming to reduce or eliminate the need of bentonite to achieve protein stabilization. In addition to protein stabilization, bentonite is also added into the must prior to fermentation to aid settling and clarifying juice. In general, addition of bentonite into juice/wine has been reported to reduce significantly the concentration of proteins, as well as, remove some aroma and flavour compounds. Bentonite treatment also affect the fermentation dynamics and foamability of sparkling wine. This review will discuss all aspects associated with bentonite application in wine production and its impact on wine composition and quality, including the preliminary results from a recent New Zealand Winegrowers funded bentonite trial (NZW 15-105).