Why do commercial vineyards often harvest at night?

Commercial vineyards harvest during the night largely to keep berry temperatures cool, about 50°F (10 °C). Keeping berry temperatures low allows for the preservation of compounds that give grapes their delicate aromas, which can evaporate during the daytime heat. Night harvesting ensures that grapes arrive at the processing facilities with their full flavor potential intact.

Cool temperatures at night greatly inhibit the activity of microorganisms. Yeasts and bacteria remain dormant at temperatures below 60°F (15°C), preventing a premature fermentation process in the transport bins. This gives winemakers complete control over the timing of fermentation, as well as the conditions under which it occurs.

The 30% aroma preservation difference is particularly critical for premium wine varieties like Sauvignon Blanc and Pinot Noir. The volatile thiols in these compounds are lost quickly at temperatures above 70°F (21°C). Night harvesting will preserve the more delicate floral notes and aromas that would be lost during daytime harvesting.

Despite the increased energy costs for lighting due to night vineyard operations, the quality premium offsets the extra expense. Top wineries can charge their consumers 15-25% more for wines harvested at night. This is now a standard operating procedure for wines in premium wine regions worldwide.

Read the full article: When to Harvest Grapes: The Essential Guide