Relationship between Plate Waste Ratio and Food Category or Serving Amount in Elementary School Lunches

Abstract

School lunches present opportunities for Shokuiku (food education), but only a few studies have addressed factors that contribute to plate waste. The purpose of this study was to evaluate the relationship between plate waste ratio and food category or serving amount. We determined the amount of lunch plate waste in an elementary school over the course of a year. Each dish was categorized and plate waste ratios were compared using the Kruskal-Wallis test or Mann-Whitney test. The mean plate waste ratio was 7.3±5.1%/year. Among each food category, the plate waste ratio was higher with vegetable dishes (9.4±5.3%) than grain (5.7±3.9%) or desserts (3.9±2.8%); higher with white rice (7.8±3.4%) than seasoned rice (5.1±4.2%); higher with fish (8.7±4.0%) than meat (6.3±4.7%); and higher with Japanese main dishes (8.1±5.1%) than Western main dishes (5.8±4.1%). Among the school grades with equal serving amounts, i.e., early (grade 1 and 2), middle (grade 3 and 4), and late (grade 5 and 6) grades, plate waste ratios were significantly higher in earlier grades. Our findings suggest that food category and serving amount correlated with plate waste ratio. Further studies will be needed to assess other factors that influence plate waste ratio, such as student characteristics and food education.