A study conducted by the University of Manchester has found that sandwich manufacturers could reduce carbon footprint by as much as 50% if they decided to change recipes and reduce waste. The team of scientists investigated the carbon footprint of 20 different ready-made sandwiches and 20 homemade sandwiches.

The largest carbon footprint of read-made sandwiches was the all-day breakfast, followed by ham and cheese, and prawn mayo. At the bottom of the list, with nearly half of the carbon footprint of the three mentioned above were the egg mayo and cress, chicken and sweetcorn, and tuna and sweetcorn sandwiches.

Professor Adisa Azapagic from the University’s School of Chemical Engineering and Analytical Sciences commented on the research: 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.

Big carbon savings could be found in the agricultural production and processing of the ingredients, which accounts for up to two thirds of a ready-made sandwich’s carbon footprint. Changes in the recipes could really make a difference, suggest the study. For example, using smaller amounts of meat, eggs, and cheese could reduce the impact by 1.1-10%. Not using tomato and lettuce could lower the footprint by 3.3-8.9%, while excluding mayo lowers it by another 1.7-8.4%.

However, changes in the recipes have to be accepted by the customers and by the sandwich producers. Product quality, safety, ease of preparation in commercial conditions, and nutritional value have to be considered as well, says the report.

Reducing food waste could bring a reduction of 3.1-8.5%, while considering changing the packaging could also make a difference. Commercial sandwiches undergo rigorous shelf-life testing and are normally safe for consumption beyond the use-by date stated on the label, added Professor Azapagic.

Here is the full list of ready-made sandwiches with the largest carbon footprint:

All-day breakfast 1,441.3
Ham and cheese 1,349.5
Prawn and mayo 1,254.7
Egg and bacon 1,182.4
Ham salad 1,119.1
Cheese Ploughman’s 1,112.1
Sausage and brown sauce 1,087.2
Double cheese and onion 1,078.4
Cheese and tomato 1,067.3
Roast chicken and bacon 1,030
Bacon, lettuce, tomato 1,007.4
Ham and mustard 1,000.5
Roast chicken and stuffing 991
Ham and mayo 978.2
Cheese and mayo 976.2
Chicken salad 963
Cheese and pickle 956.4
Ham and egg 947.8
Tuna and cucumber 942.9
Chicken and mayo 887
Free-range egg and rocket 853.8
Tuna and sweetcorn 851.6
Chicken and sweetcorn 769
Egg mayo and cress 739

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