Thermal Treatment of Wine Grapes: Laccase Denaturation and Sensory Defect Removal Flavor 101A-Recognizing Off Flavors UC Davis 09 December 2011 Rick Jones Consulting Winemaker Della Toffola USA

The Goal is Simple:  Permanently deactivate laccase by heat denaturation of the protein.  But there’s a catch…you must heat to very high temperature (greater than 150 F) RAPIDLY or you can make things worse!  Why?

Enzyme Activity Increases with Temperature

3 General Methods 1.Classic Thermovinification Heat to 140 F, hold for 2-12 hours, chill, press and ferment + good color + inexpensive capital requirements - poor tannin extraction - energy intensive (need to heat and cool) - heating usually not fast enough for denaturation 2.Hot Maceration (MPC) Heat to 140 F, hold for 2-24 hours, chill, ferment on skins + For higher quality grapes - On Skins ferment can cause reintroduction of moldy character 3.ThermoFlash or Flash Detente Heat quickly to 180F followed by immediate cooling in a vacuum chamber + good color AND tannin extraction + ability to press off a balanced must immediately to discard moldy skins + complete laccase denaturation + entrainment of moldy character in flash water that can be discarded - expensive

The COOLER UNIT