A Minimally Invasive Approach for Preventing White Wine Protein Haze by Early Enzymatic Treatment

Protein stability in bottled white wine is an essential organoleptic property considered by consumers. In this paper, the effectiveness of an early enzymatic treatment was investigated by adding a food-grade microbial protease at two different stages of winemaking: (i) at cold settling, for a short-term and low temperature (10 degrees C) action prior to alcoholic fermentation (AF); (ii) at yeast inoculum, for a long-lasting and medium temperature (18 degrees C) action during AF. The results reveal that protease sufficiently preserved its catalytic activity at both operational conditions: 10 degrees C (during cold settling) and 18 degrees C (during AF). Furthermore, protease addition (dosage 50-150 mu L/L) raised the alcoholic fermentation rate. The treatment at yeast inoculum (dosage 50 mu L/L) had a remarkable effect in preventing haze formation, as revealed by its impact on protein instability and haze-active proteins. This minimally invasive, time and resource-saving enzymatic treatment, integrated into the winemaking process, could produce stable white wine without affecting color quality and phenol content.

Automated summary

This study investigated the effectiveness of adding protease in the winemaking process, and found that it preserved its catalytic activity and improved alcoholic fermentation rate. The addition of protease also prevented haze formation. This enzymatic treatment method can achieve stability control in white wine quality.