AN OPTICAL METHOD FOR DETECTING WATERCORE AND MEALINESS IN APPLES

Spectral reflection in the wavebands between 600 and 1100 nm was tested for its ability to classify apples according to the presence of watercore and mealiness. A model developed by partial least squares (PLS) regression using four, 10 nm wide wavebands at 690, 700, 820, and 830 nm separated watercore and normal apples with an error of 4%. It was found that watercore could only be detected shortly after the apples were harvested. Classification of the watercore apples into slight, moderate, and severe categories may be possible if models are based on a higher number of samples. Mealy apples could be detected from normal and watercore apples in all cases using the reflectance in the 1020, 1040, 1050, and 1095 nm wavebands. Attempts to measure the degree of mealiness, based on spectral reflection, provided no useful results.