Food waste at the household level accounts for a significant share of total food waste in developed economies, according to the Food and Agriculture Organization. Studies have shown that this share varies between 0.3 kg to 4.5 kg per person per week, depending on the definitions and methodologies applied. In Italy, quantities, behaviors, and attitudes regarding food waste have been solely explored through the use of questionnaires, typically leading to discrepant values of food waste. In this study, we estimate and analyse the determinants of food waste over a 388 units’ panel spread over the national territory, through a diary and questionnaire study. Moreover, by comparing food waste value that was declared in questionnaires and reported in diaries, we confirm that the awareness of food waste quantities is heavily biased. The results confirm that the average food waste value is significantly higher when gathered through diaries, while questionnaires are able to catch less than one-third of food waste determinants.

Purpose The purpose of this paper is to assess the reliability of questionnaires as a method of quantifying household food waste (FW), thus providing context regarding the validity of existing Italian estimates. Design/methodology/approach A total of 30 households were involved in a diary study that was conducted for one week. The participating households were first asked about their FW quantities in a questionnaire. Half of the households who filled their diaries properly were then audited through waste sorting analysis performed on their garbage. Non-parametric tests were used to test for differences in FW estimates between audited and non-audited households, as well as differences among estimates obtained through different quantification methodologies. Findings Edible FW was estimated to be 489 grams per week based on questionnaires, and 1,035 grams per week based on diaries. In the audited sub-sample of households, FW estimates were 334 grams per week based on questionnaires, 818 grams per week based on diaries and 1,058 grams per week based on waste sorting analysis. Research limitations/implications Given the small sample size in the present study, future studies can utilize larger samples to assess whether the differences identified in estimates can be replicated. Future studies can also inquire into the behavioral biases that led consumers to underestimate their FW. Practical implications Results of the present study point against the use of questionnaires to quantify household FW, hence raising some doubt on the reliability of existent Italian estimates. Where waste sorting is unfeasible, the use of adjustment methods or diaries is suggested to better inform policies. Originality/value This study is one of the first on FW quantification that tests three different methodologies on the same sample, and is the first to do so in Italy, where estimates are still very poor.

Household food waste is considered to be the largest share of food waste along the food supply chain. Given that its recoverability is also more challenging compared to food waste in other stages of the chain, most studies on household food waste adopt a pre‐emptive approach by aiming to identify and address consumer beliefs, attitudes and actions that are linked to food waste. In scientific literature, household food waste has often been studied in relation to the habit of purchasing discounted food products (DFP). However, findings have been contradictory. Specifically, while some authors found that deal‐prone consumers are usually of lower income and therefore display a wiser and more attentive attitude towards grocery shopping, other authors reported that the purchase of discounted products was usually linked to compulsive shopping, hence resulting in higher food waste quantities at home. Due to these discrepant findings, a definitive answer on the impact of DFP on household food waste does not currently exist in the literature. This paper analyses the correlation between the purchase of DFP and weekly household food waste quantities. To do so, we examine (a) the results of a food waste diary experiment carried out on a representative sample of 385 households in Italy in February 2017, and (b) the results of a 23‐items Computer Assisted Web Interview survey administered to the same householders, in which shopping habits were investigated. Results revealed no evidence of either a positive or negative relationship between the purchase of DFP and household food waste quantities. Frequency of grocery shopping was the only variable found to have a significant impact on household food waste quantities.

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