Prevention and Under-Reporting Effects of Food Waste Diaries

One method of quantifying food wastage in households is a food waste diary. The goal of this study is to evaluate the reliability of food waste diaries as a methodology of waste-level measurements. This form of self-reporting is considered to underestimate the levels of food wastage because of three phenomena. The so-called self-selection bias is minimized by the chosen study set-up. The under-reporting and prevention effects were determined by measuring the food waste levels amongst 80 participating households. In week 1, the food waste amounts were determined by individual waste sorting analysis; in week 2, they used a food waste diary followed by a waste sorting analysis. The use of food waste diaries leads to a considerable prevention effect of 20%. Individual sorting analysis of uninformed households showed a generation of 59 kg∙inh−1∙yr−1 of avoidable food waste and 28 kg∙inh−1∙yr−1 of non-avoidable food waste. When using food waste diaries, these amounts dropped to 47 and 23 kg∙inh−1∙yr−1, respectively. In the study, instead of an under-reporting effect, the analyses showed an over-reporting of 7%. In medium-rise housing, the food wastage level is lower than in the overall population of the study, whereas both the prevention effect and the over-reporting is higher. Low-rise housing shows the highest initial food waste level. High-rise housing shows the smallest prevention effect. In the countryside, both the food wastage level and the prevention effect are significantly lower than elsewhere. In smaller towns, a slight under-reporting effect was observed; elsewhere there was an over-reporting effect. Further research might focus on if and how long the prevention effect of the food waste diaries lasts amongst Polish households.