This study aims to explore the factors that influence plate waste at lunches served in primary schools. Data was collected for all fourth-grade children attending 21 primary schools from the city of Porto (Portugal) (n = 463). Plate waste was evaluated by the weighing method and factors influencing plate waste were collected by observation of menu and canteen characteristics and through the application of a questionnaire to children aiming to evaluate factors related to preferences and dietary patterns. Logistic regression was performed to identify predictors of plate waste. It was observed that fish menus and composed dishes showed a higher tendency for increased plate waste. However, this effect was not observed when adjusted for other variables. Soups without pulses and blended soups were less likely to be discarded by children. The presence of the teacher during meals and the possibility for children to leave the canteen whenever they wish, protected both the main dish and the soup from being wasted. A higher number of children in the canteen was associated with increased soup waste. As expected, children more pleased with the sensory characteristics of the main dish and soup were less likely to waste food. Children who consumed high-saturated fat content mid-morning snacks were more likely to waste soup.

The main factors associated with plate waste were related to the presence of teachers during the mealtime, school meal policies and the meals’ sensory characteristics. Additionally, soup waste was determined by its composition, mid-morning snacks and the number of children in the canteen.

本研究旨在探讨影响小学午餐时餐碟浪费的因素。收集了来自葡萄牙波尔图市（n = 463）在21所小学就读的所有四年级儿童的数据。通过称量法评估餐盘废物，并通过观察菜单和食堂特征并通过对儿童进行问卷调查收集影响餐盘废物的因素，旨在评估与偏好和饮食习惯相关的因素。进行逻辑回归以识别板料浪费的预测因素。据观察，鱼类菜单和组合菜显示出更高的增加盘子浪费的趋势。但是，在针对其他变量进行调整时，未观察到这种效果。没有豆类的汤和混合汤很少被儿童丢弃。用餐时老师在场，以及孩子们随时随地离开食堂的可能性，保护了主菜和汤免于浪费。食堂中更多的儿童与汤浪费增加有关。不出所料，孩子们对主菜和汤的感官特征更加满意，因此他们浪费食物的可能性较小。在上午中段吃掉高饱和脂肪的儿童更容易浪费汤。

与餐盘浪费有关的主要因素与就餐时间的教师人数，学校的就餐政策以及就餐的感官特征有关。此外，汤废料还取决于其成分，上午零食和食堂中的儿童人数。