Lighting Systems for Fruit and Vegetable Sorting (E2559)
Fruits and vegetables are inspected prior to most packing or processing operations. The purpose of inspection is to sort out (discard) the individual items that have characteristics undesirable for fresh market sale or for processing.
Fruits and vegetables are inspected prior to most packing or processing operations. The purpose of inspection is to sort out (discard) the individual items that have characteristics undesirable for fresh market sale or for processing. Most sorting is done by human visual inspection. Workers perform the manual sorting operation as the fruits or vegetables move past them rapidly on roller or belt conveyors. Each worker typically must look at a few hundred items each minute, and accurately discard those that are unacceptable. Good lighting conditions are necessary for good sorting efficiency.
“Light” is a very general tem and, in most applications, is taken for granted. Lighting, however, may not match well with the specific task for which it is intended. Specific guidelines for lighting system design in fruit and vegetable sorting and packing lines in the United States do not exist. Manufacturers of packing line equipment have left lighting decisions up to the individual operation. Improper selection of equipment results in lighting that is inadequate for conducting the inspection.
Agricultural products can cover the entire spectrum of visible colors. A given product is usually within a well-defined color range, but color variation on and between items can be high. Defects can occur anywhere on the fruit or vegetable, be of any size, and occur in a variety of colors. Light provided for inspection must have BOTH adequate intensity and adequate color quality to enhance or reveal these defects, rather than obscure or mask them.
Improper lighting design promotes worker fatigue and eye strain, and results in poor sorting efficiency. Studies of several operations involving inspection of a range of fruit and vegetable commodities have shown that many lighting systems are not adequate for the required task. These studies suggest that sorting could be improved if inexpensive changes in illumination sources, illumination intensities and background colors were adopted in sorting areas.