A heat shock was applied to Saccharomyces cerevisiae: a change from 18 degrees C to 45 degrees C over 5 min and then maintenance at later temperature for 20 min followed by cooling to 18 degrees C. Such a treated inoculum, when used in an alcoholic fermentation of Welsch Riesling grape must at 18 degrees C, gave up to 12 g glycerol l(-1). This is a new and easy method for high glycerol production in large scale wine production.