Near-Infrared Method Can Be Used for Grapes

Since grapes grow in bunches, the nondestructive estimation of Brix in grapes by the near-infrared method cannot be used. Another method, therefore, to take the place of the near-infrared method has been developed. 1) A high correlation was found between the specific gravity (weight/volume) of a bunch of grapes and the Brix of its juice. Therefore, if the specific gravity of a bunch is obtained by measuring both the volume and weight of a bunch, the Brix can be estimated by a regression line between the specific gravity and Brix. The statistical error of the measurement was around 0.5 (Brix).

Acoustic Volume Meter

The volume of a bunch of grapes can be measured very quickly by means of an acoustic volume meter. Compared with the near-infrared method, this new method using an acoustic volume meter has the merit of lower cost, while the device is smaller. Accordingly, this method seems to be best suited to small-scale fruit sorting and retailing.

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