Optical Methods for Nondestructive Quality Evaluation of Agricultural and Biological Materials

Literature which reports on optical methods of nondestructive quality evaluation of agricultural and biological materials is reviewed. The basic laws and interaction of light with biological materials are presented with particular regard to their applicability in quality evaluation. A wide range of agricultural and biological materials such as fruits, vegetables, seeds, cereal grains, eggs and meat products are considered. Optical evaluation of maturity, viability, external damage, internal defects and other quality attributes are dealt with. The suitability of each method to successfully indicating defective samples is examined. The phenomenon of delayed light emission (DLE) by green plant materials and the factors affecting it are presented. The potential of DLE in nondestructively evaluating the quality of fruits and vegetables is discussed and its advantages over conventional spectrophotometric methods are considered. From the information cited in this review, data on optical properties of each product serving as an index of quality are put together in a single table to serve as a ready reference. Possible future approaches of further research in optical methods of quality evaluation are also discussed.