A new study has revealed that sandwiches are having a substantial impact on greenhouse gas emissions. In the first study of its kind, researchers at The University of Manchester have tracked the carbon footprint of a sandwich by examining its entire life cycle including production, packaging, and food waste.
The research team focused on 40 sandwich recipes for their investigation. The highest carbon footprints were found in sandwiches that contained bacon, ham, or sausage, as well those made with cheese or prawns.
The most carbon intensive process was discovered in sandwiches served on all-day breakfast menus that include eggs, bacon, and sausage. The study revealed that the production of just one of these sandwiches generates a carbon dioxide equivalent (CO2 eq.) that is comparable to driving a car for 12 miles.
The lowest carbon footprint was found in a sandwich made at home with ham and cheese. Furthermore, the study demonstrated that sandwiches made at home could reduce carbon emissions in half compared to eating out.
According to the British Sandwich Association (BSA), more than 11.5 billion sandwiches are consumed each year in the UK. Around half of those are made at home and the other half are bought in shops, supermarkets, and service stations.
“Given that sandwiches are a staple of the British diet as well as their significant market share in the food sector, it is important to understand the contribution from this sector to the emissions of greenhouse gases,” said study co-author Adisa Azapagic.
“For example, consuming 11.5 billion sandwiches annually in the UK generates, on average, 9.5 million tonnes of CO2 eq., equivalent to the annual use of 8.6 million cars.”
The researchers established that the biggest contributor to the carbon footprint of a sandwich is the agricultural production and processing of the ingredients, which generates up to 67 percent of the CO2 eq. for fast food sandwiches. In addition, the refrigeration of sandwiches in the supermarket can account for up to 25 percent of their overall contribution to emissions.
“We need to change the labelling of food to increase the use-by date as these are usually quite conservative,” said Professor Azapagic. “Commercial sandwiches undergo rigorous shelf-life testing and are normally safe for consumption beyond the use-by date stated on the label.”
The study authors pointed out that reducing certain ingredients that have a higher carbon footprint such as cheese and meat would not only help to cut back on greenhouse gas emissions, but would also contribute to healthier diets with less calories.
The research is published in the Journal of Sustainable Production and Consumption.