Automated Quality Inspection of Citrus Fruits – A Review

Non-destructive quality inspection of fruits provides quality products for domestic consumption as well as for export markets, increasing consumer/buyer confidence. It provides assurance of quality and subsequent value addition. A major thrust of current research is towards the development of quality inspection systems for improved sorting and automated quality control. Machine Vision inspection has received wide attention in recent years, due to various advantages compared to the conventional manual inspection. These systems typically sort the objects based on various quality features like colour, size, shape, etc. Handling of fruits for presenting them before the camera for grading and subsequent sorting plays a major role in determining the overall performance like throughput etc. The present paper reviews with special focus to citrus fruits, the evolution of traditional fruit sorting and grading techniques and the subsequent machine vision based systems with improved fruit handling and improved techniques for inspecting the fruits for various quality parameters like size, shape, colour, defects, etc. The review covers the different approaches used based on image analysis for quality inspection of citrus fruits in grading and sorting. The review aims to investigate the potential of various techniques like machine vision, infra-red, optical, robotics, mechatronics, etc in quantifying the quality parameters of citrus fruits, like colour, size, shape, etc. and explore the possibilities towards development of improved machine vision based systems for inspection of local varieties of horticultural produces, particularly citrus fruits like orange, mosambi and lemon.