EFFECTS OF STORAGE DURATION ON DETECTING WATERCORE IN APPLES USING MACHINE VISION

Measuring the amount of light transmitted through an apple has had lim ited success for detecting watercore in apples when the measurements w ere made soon after harvest. However, errors associated with this tech nique when applied to apples coming out of cold storage has yet to be determined Using a machine vision system to view the stem-end of the a pple while illuminating the calyx, the intensity of light transmitted through individual apples was measured biweekly for 14 weeks in 1990. The mean gray-level of the pixels within a square window centered abou t the stem was representative of the intensity of the light transmitte d through the fruit. The intensity of light transmitted through the fr uit decreased with time for all classes of watercored fruit. Based upo n the initial levels defined for each class, this decrease in light tr ansmission resulted in misclassifying watercored fruit as watercore-fr ee at the end of the time study. Of 72 fruit initially classified as s everely watercored, 18% of the fruit were misclassified as watercore-f ree, because three apples still had evidence of watercore, while eight fruit exhibited internal browning, due to watercore.