During ripening, red grapes change from a green color to what?

During the ripening process, red grapes undergo a significant transformation in color due to the accumulation of anthocyanins, which are pigments responsible for the red, purple, and blue hues in many fruits. As the grapes mature, the green chlorophyll that dominates their initial appearance breaks down, allowing these anthocyanins to be more visible. The typical color change for red grape varieties during ripening is from green to shades of purple, which indicates that the grapes are developing flavor complexity and sugar content, essential for wine production.

Purple is the most common color observed due to the variety of grapes and their specific characteristics; different grape varieties may have slightly varying shades of purple, but the fundamental color transition during ripening across most red grape types tends toward purple. This is consistent with how winemakers assess ripeness and quality during the grape harvest, as color is an important indicator of the grapes' readiness for vinification.