Quantification of household food waste in Greece to establish the 2021 national baseline and methodological implications.

The aim of this study was to present the national-level quantification of household food waste in Greece for 2021, in alignment with the legal framework of the European Union (EU) for measuring and reporting food waste. An online diary survey was conducted in spring 2021, utilizing pre-tested semi-structured food waste logs. Descriptive statistics were employed to analyze food waste levels and generalized estimating equations (GEE) were performed to assess the influence of diary duration on food waste levels. The final representative sample consisted of 1,133 households. At the national level, the average per-capita annual total food waste generation rate was 86.5 ± 64.5 kg. The predominant share of food waste (47 %) was inedible plant-derived parts, reflecting underlying consumption patterns, whereas 40 % was once-edible food parts. Particularly, vegetables, fruits, and bakery products were the most discarded once-edible food items. Moreover, no statistically significant difference was found between food waste levels across the diary entries, with reporting periods varying from one day to one week. This study marks the first implementation of the EU legislation for household food waste measurement and reporting in Greece. Moreover, the study results indicate that the utilization of diaries with shorter reporting periods than one week, with a sufficiently large sample, may be an appropriate method for measuring nationwide levels, enhancing compliance while mitigating social desirability bias and reducing attrition. Future research should delve into the behaviors driving food waste, motives for prevention in different geographic and cultural contexts, and optimal diary reporting durations.