Monitoring harvesting degree of red Scarlet apples using DR-UV-Vis and NIR spectroscopy

Establishing the optimal harvest time is a fundamental issue for apple fruit industry, since fruit shelf life and quality are related to the ripening stage at harvest. Ripening indexes determination through destructive analysis is invasive for fruits and is limited to a low sample number. This work is focused on the study of red apples ripening (Scarlet variety), with the aim of better identifying harvest date characterizing each stage of fruit ripening on trees using classical analysis and non–destructive analysis. UV-Vis spectroscopy is performed in diffuse reflectance mode to monitor variation of chlorophyll concentration in the skin of apples during ripening on trees; in fact, in the case of fruits as red apples the colour variation is hardly visible as ripening goes on, and ground colour cannot be considered a valid tool of ripening identification. Conversely chlorophyll monitoring using DRS-UVVis spectroscopy appears to be a reliable indicator of the ripeness level.