Development, Evaluation and Improvement of Apple Infield Grading and Sorting Systems

Abstract

AbstractInfield grading and sorting could help apple growers achieve cost savings in postharvest handling by removing inferior fruit that are not suitable for fresh market consumption. An apple infield grading and sorting system, including sub-systems of singulation and rotation, grading, and sorting, was developed. The grading system’s repeatability coefficients >90% and >81% for the intra- and inter-lane, respectively, demonstrated its satisfactory performance for infield use. The rotary sorter (RS), consisting of a rotary disc and two pivotable gates to guide apples into different bins according to grading results, could not meet the requirements in terms of high apple bruising rate (<95% apples in Extra Fancy level), bulky sizes (610 mm height), complex hydraulic power transmission system, and unacceptably low sorting accuracy. To address the issues caused by RS, a simple and compact paddle sorter (PS), consisting of a solenoid and a paddle, was designed and constructed. Extensive tests of the PS resulted in 100% of apples graded as Extra Fancy, which had a superior performance over RS. By replacing the RS with the PS, the overall height of the sorting system reduced from 610 to 350 mm, making it more convenient for transportation and infield use. Furthermore, the hydraulic power transmission system was simplified significantly by eliminating a majority of components (e.g., angle gearbox, coupler, and sprocket) when the RS was replaced by the PS. The PS achieved sorting accuracy >99%, which demonstrated its satisfactory and reliable performance. The apple infield grading and sorting system with the PS incorporated is bruising free, compact, simple, and satisfactory in sorting accuracies (>99%), indicating its potential for long-term commercial use.KeywordsAppleInfield sortingGradingAutomationHigh throughputBruising