Industrial freeze-drying of courgette sometimes leads to the alteration of both the appearance and the texture of the freeze-dried product and to varying freeze drying times. Two factors may be involved in these phenomena: the freezing rate and the ripeness state of the raw material. In this study, we show that the freezing rate has no influence on the final quality of the product nor on the dehydration time. On the other hand, the degree of ripeness seems to be of prime importance and can be easily estimated by colorimetric measurements on the fresh vegetable skin or by calorimetric measurement of the glass transition temperature. We also propose a colorimetric criterion for selecting courgettes before processing and predicting the luminance of the freeze-dried product.