The Course of Changes in the Starch Index of Apples Calculated Using Selected Optical Instruments

The aim of the study was to check the usefulness of computer image analysis methods in calculating the starch index (S) value. Starch index determined properly facilitates the harvesting of fruit at the optimal time for a given variety. Starch tests were performed on apple fruit of two varieties: Gloster and Jonagold, with circular and radial starch disintegration on the surface of their cross-section. Images were recorded using selected digital image recording methods. During the four-year experiment cycle, they were assessed in terms of the course of starch breakdown using visual assessment (VA) and three optical techniques (BW – black and white images of slices (CCD camera), DC – colour images from a digital camera, SC – images from scanner). Relationships were determined between simple regression equations illustrating the course of changes in S as a function of time. According to the methodology proposed by Janishidian et al. (2005), the values of the probability of compliance of the course of the compared straight pairs were calculated. It was shown that the course of straight lines obtained using the program, which is a component of the Supervist system software (used only in the BW method), was characterized by the highest compliance.