Miniaturised LED Prototypes for Ripeness Evaluation Directly In Field: Test on Grape (Vitis Vinifera L.)

Monitoring the grape ripening until the harvest is a crucial issue since berry quality is closely related to it. Therefore, the research for non-destructive methods which could explore many samples and give a rapid and comprehensive overview of ripening would be helpful. The aim of the research was to design, build and test prototypes of miniaturised low-cost and user-friendly devices envisaged mainly to support small-scale growers. The systems were tested to monitor the ripening of grape until harvest. Pre-prototypes of fully integrated, stand-alone optical device were designed and built. Two systems equipped with digital 6-channel sensors each in the visible and SW-NIR from 400 nm to 860 nm were proposed. Optical analyses were collected on grape berries and grape bunches using the two prototypes and reference parameters (SSC and TA) were carried out on each sample. The MLR correlation models between the optical data from the prototypes and the reference parameters were calculated. Results of prototypes test were encouraging underlining a small loss of performance compared to commercial devices using the full spectra.