Non-Destructive Estimation Pigment Content, Ripening, Quality and Damage in Apple Fruit with Spectral Reflectance in the Visible Range

Modern non-destructive optical-reflectance-based techniques for estimation of pigment (chlorophyll, carotenoid, anthocyanin, and flavonol) contents, the rate of onand off-tree ripening as well as for detection of common physiological disorders, such as sunscald, superficial scald, and water core, and other damages to apple fruit are reviewed with an emphasis on the methods developed by the authors. The basic spectral features of fruit reflectance in the visible and near infra-red are briefly considered together with their implications for the development of algorithms for non-destructive pigment content assessment. The use of reflectance spectroscopy for estimating chlorophyll and carotenoid content as well as carotenoid/chlorophyll ratio during fruit ripening is demonstrated. The algorithms developed for fruit peel pigment analysis and for estimation of ripeness are presented with consideration of the limits of their applicability. Special attention is paid to adaptation of apple fruit to strong sunlight at preharvest stage and its consequences for postharvest fruit quality. _____________________________________________________________________________________________________________