QUALITY SORTING OF SOME VEGETABLES BY COLORIMETRIC CRITERIA : A REVIEW (RESEARCH AND DEVELOPMENT IN FRANCE)

Colorimetric sorting of fruits and vegetables is not yet usual in France. Numerous technics fonded on reflectometric measurement exist and need to be improved. In the future, the sorting will likely be made by video systems using camera connected to a microcomputer. Some prototypes are already developped and give satisfactory results on tomatoes when used in conjunction with classical sorting machines.

In another way, the simple devices using photoelectric cells and photodiodes can be improved and make useful for different products. The main outlines of a versatile apparatus are proposed. It seems possible to use this device for heterogeneous material even in difficult cases (artichoke, carrot, eggplant). Optical systems using interferential filters must be adapted for each case.

From an agronomic point of view, these new technics are still ignored by breeders. The pigmentation would be considered as a marker of the physiological maturity linked to the technologic, sensory and nutritional qualities. The earliness of pigment synthesis, more particularly in fruits, and the uniform color are criteria of breeding in order to collect the vegetable product in a single harvest. In fact, these characteristics often hide an heterogeneity in the physiological state of maturity which gives rise to problems in storage and trading. This visual criterion must be preserved in order to be an objective basis in the colorimetric (hand-made or automatic) sorting of horticultural productions.