Small-Scale Fining Trials: Effect of Method of Addition on Efficiency of Bentonite Fining

Abstract

Laboratory-scale fining trials are used to estimate the amount of bentonite needed to reduce potential haze of commercial wines. Several factors influencing the efficiency of bentonite fining in the reduction of haze-forming potential of white wines were examined, including age of bentonite slurry, method of addition, mixing rate, and variation between personnel. The manner and extent of bentonite dispersal in wine determines both the amount of protein adsorbed and the degree to which heat/chill induced haze is reduced. When vigorous mixing follows bentonite addition, haze potential is one-third that of samples stirred at a slower rate. Samples mixed at higher rates may be more reproducible in their protein content and haze potential, but these methods often do not reflect cellar practices, leading to underestimation of the amount of bentonite necessary to achieve desired levels of stability. Significant variation between repeated finings performed by single individuals suggests that several replicate fining trials are required to determine the appropriate fining level. Experimental finings should be compared with the reduction in haze potential achieved in the cellar in order to refine the small-scale trial methodology so that it reflects the behavior of bentonite in production-scale treatments.