Wine glossary

physiological ripeness
Definition:the stage of peak ripeness, when optimal aromatic development in the grape is achieved and when the phenolics in the black grapes are perfectly ripe

The exact definition of physiological ripeness is extremely difficult to define, and can often be controversial, usually being based on specific habits.  Whereas, at one time, the must weight was a decisive factor, as time passed, the acidity values and pH levels also began to play a role. Nowadays, the pips of the grapes define the physiological ripeness of a grape, and should be slightly brown in colour, have a mild, nutty taste, and not be too interwoven with the flesh of the grape.