Aspartic Acid Protease from Botrytis cinerea Removes Haze-Forming Proteins during White Winemaking

White
wines suffer from heat-induced protein hazes during transport
and storage unless the proteins are removed prior to bottling. Bentonite
fining is by far the most commonly used method, but it is inefficient
and creates several other process challenges. An alternative to bentonite
is the enzymatic removal of haze-forming grape pathogenesis-related
proteins using added proteases. The major problem with this approach
is that grape pathogenesis-related proteins are highly protease resistant
unless they are heat denatured in combination with enzymatic treatment.
This paper demonstrates that the protease BcAP8, from the grape fungal
pathogen Botrytis cinerea, is capable
of degrading chitinase, a major class of haze-forming proteins, without
heat denaturation. Because BcAP8 effectively removes haze-forming
proteins under normal winemaking conditions, it could potentially
benefit winemakers by reducing bentonite requirements.