There's a change in the colour of the pips that marks the onset of physiological ripeness, from green to yellow, which is the critical point at which to harvest.

So as well as chemical measurement, winegrowers these days tend to taste grapes from different parts of the vineyard as they walk through to subjectively rate their physiological ripeness.

Amino acid fertilizer was used in ripening stage for improving the yield and fruit quality of Red Globe grape in postpone culture.