Sorting table illumination on stonefruit packing lines in California

Sorting table illumination was evaluated in nine stonefruit packing houses, including table configuration, light intensity, uniformity, and spectral quality. Typical sorting tables had two sorting lanes with a cull lane running between, and the fruit were moved by roller conveyor made from white PVC pipe. Luminaires with two fluorescent lamps were usually centered above and along each sorting lane section. Correlated color temperatures of the lamps varied from 3600 to 5000° K, and color rendering indices varied from 62 to 90. Illuminance at the center of each sorting lane ranged from 920 to 4080 lx (85 to 379 fc), with a mean value of 2170 lx (202 fc). Light intensity was relatively uniform over the entire surface of the sorting lane. Luminance ratios between the white roller conveyors and darker fruits exceeded the 3:1 industry recommendation and could be improved by using darker rollers. The majority of packing lines used “cool-white” fluorescent lamps. Color rendering might be improved with lamps having higher correlated color temperatures and color rendering indices, thereby more closely approximating daylight. Defect recognition might be enhanced with lamps having more energy in the red region of the spectrum.