Crushed by the Heat

Picking grapes at night results in better wine, lower energy costs and happier workers. High daytime temperatures (90 and up) change the sugar composition of grapes leading to possible uncontrolled fermentation due to wild yeast. To bring down the temperature, grapes are put through a cold bath or heat exchanger before being crushed. While that gives vintners more control, it costs money. Picking at night obviates this need and keeps workers from heat stroke.