A Review on the Development of Onion Sorting and Grading Machine

Abstract

Onion cultivation is a vital part of Philippine agriculture, contributing to the nation's economy and rural employment. However, the small-scale onion farmers faced challenges in sorting and grading, including reliance on manual labor, lack of mechanized equipment, and postharvest losses due to manual handling. This paper aims to review and to analyze existing onion grading technology in both mechanical and automated to identify most efficient and cost-effective solutions suitable for small-scale farmers in the Philippines. While automated onion graders equipped with advanced sensors show higher accuracy (up to 99%) in size classification and defect detection, mechanical onion grader such as rotating cylindrical grader and divergent roller design can achieve up to 95% grading efficiency, reduce manual labor, and provide a practical, cost-effective solution for small onion farmers facing high postharvest losses. For the design conceptualization of mechanical onion grader for small scale farmer, factors such roller rpm (13 rpm to 15 rpm) and inclination (8^o to 13^o), and drum rpm (10 rpm to 15 rpm) and inclination (3^o to 4^o) must be considered to ensure higher grading efficiency and lower percent damage. In addition, finite element analysis and discrete event modeling must be conducted to predict the effects of drum inclination, rotational speed, and feed rate on throughput and grading accuracy.