A portable non-destructive volume meter for wine grape clusters

A portable non-destructive instrument has been developed for the measurement of grape cluster volume using air displacement techniques. The design satisfies the producer's need to determine cluster growth curves in order to estimate the optimum time to start the harvest. Several ways of processing data were evaluated, including different models and parameters related to thermodynamic, mechanical and electronic aspects. Using an empirical calibration technique, the device performs with an acceptable accuracy for field measurements, with errors below 20 cm(3) and R-2 higher than 0.92. It is intended for sample volumes between 80 cm(3) and 500 cm(3). The instrument was intensively tested in three vineyards and for different atmospheric pressures, achieving good results and validating its use for harvest volume estimation. The instrument can be adapted so that it can be used for other types of fruit and vegetables.