When purchasing ready-made sandwiches, the main concern of a consumer is getting a relatively inexpensive meal in the matter of minutes. However, unbeknownst to most consumers, these convenient meals can be a convenient way to contribute to one’s carbon footprint. In the research article “Understanding the impact on climate change of convenience food: Carbon footprint of sandwiches,” Namy Espinoza-Orias and Adisa Azapagic study the environmental impacts of ready-made and home-made sandwiches, from the cultivating of their ingredients to post-consumer waste. One of the main focuses of the research article is comparing the various carbon footprints of ready-made and home-made sandwiches. Approximately 11.5 billion sandwiches are consumed each year in the UK, with approximately half being home-made and the other half being purchased pre-made (Espinoza-Orias 1). Espinoza-Orias and Azapagic use 40 different popular sandwich recipes from the UK in their study and calculate their approximate carbon footprints, with which they explore how the carbon footprints and nutritional information of sandwiches could be used to decrease carbon footprints and help consumers make better decisions about their food. Reducing the greenhouse gas emissions during the lifecycle of sandwiches could result in a massive reduction in carbon footprints, with the article suggesting that a reduction of up to 50% is possible for ready-made sandwiches (Espinoza-Orias 1).
In the first study of its kind, Espinoza-Orias and Azapagic chose 24 commercial ready-made sandwich recipes and 16 variations of the recipe for the home-made ham and cheese sandwich. The researchers then calculated the approximate carbon footprint of each sandwich’s life cycle through six categories: ingredients, preparation, retail, packaging, transport, and waste management (Espinoza-Orias 7). Empirical data was presented through stack graphs, one for each type of ready-made sandwich – pork, chicken, seafood, and vegetarian – and one for the home-made sandwiches. Through the use of stack graphs, the overall carbon footprint for each sandwich recipe and how each part of making the sandwich contributed to the footprint can be visualized, as well as the comparison of the carbon footprints between different kinds of sandwiches.
The carbon footprint of ready-made sandwiches ranges from 739 g CO2 eq. to 1441 g CO2 eq. per sandwich (Espinoza-Orias 7). The data reveals that ready-made sandwiches containing pork and cheese have the overall highest carbon footprints, but some ready-made vegetarian sandwiches have even higher carbon footprints since they include cheese, which has a higher carbon footprint than meats such as chicken and bacon. For ready-made sandwiches, the largest contributor to the carbon footprint is the production of the ingredients (37.3% to 67.1%), followed by sandwich preparation (13.1% to 24.6%) and refrigerated retail (12.4% to 24.2%) (Espinoza-Orias 7). The carbon footprint of home-made sandwiches ranges from 399 g CO2 eq. to 843 g CO2 eq. per sandwich (Espinoza-Orias 8). For home-made sandwiches, the largest contributor to the carbon footprint is the production of the ingredients (88.6% to 91.9%), followed by the retail of ingredients (3.9% to 4.6%) and packaging (1.8% to 3.5%) (Espinoza-Orias 10). Comparing the ready-made and home-made sandwiches in the study, the home-made sandwiches generally had a lower carbon footprint than the commercial sandwiches. This is partially because ready-made sandwiches are considered “high-risk foods” because they are capable of growing bacteria as they do not need to be cooked before serving, making ready-made sandwiches easily contaminated if the retailers and producers do not follow legal chilling temperatures. Another reason is that one sandwich in retail takes 20.5% more ingredients than one made at home because of food loss during the supply chain (Espinoza-Orias 10).
The researchers tested the sensitivity of the results of the study by developing twenty-two scenarios that would affect the ready-made and home-made sandwiches. Data from the sensitivity analysis was placed in a chart that gave a description of the scenario, the change in carbon footprint, and the energy content, allowing for an easy recognition of the change in the scenario and the results. In scenarios 1 and 2, the cultivation of tomatoes and lettuce was altered. The overall carbon footprint decreased by 6.9% to 11.1% when tomatoes were heated by waste heat and lettuce was grown in warmer seasons and increased by 5.1% to 14% when tomatoes were heated by electricity and lettuce by natural gas (Espinoza-Orias 12). In scenario 3, white bread was changed to wholemeal bread which made almost no difference for the carbon footprint of commercial sandwiches (<0.1%) but lowered home-made by up to 2.1% (Espinoza-Orias 12). In scenarios 4 to 6, tomatoes, lettuce, and mayonnaise were excluded. Excluding tomatoes and lettuce from the sandwiches saw a reduction of 3.3% to 8.9% in the carbon footprint and minimal energy content loss (Espinoza-Orias 12). Excluding mayonnaise saw a reduction of 1.7% to 8.4% for ready-made and 4.3% to 9.1% for home-made sandwiches, but there was a significant energy loss (Espinoza-Orias 12). In scenarios 7 to 9, the amount of meat and eggs were reduced by 10% and the amount of cheese was reduced by 20%, which reduced the total carbon footprint by 1.1% to 10% (Espinoza-Orias 12). In scenario 10, food waste was reduced in the food production of ready-made sandwiches, which resulted in a reduction of the carbon footprint by 3.1% to 8.5% (Espinoza-Orias 12). Lastly, scenarios 11 to 22 used alternative packaging and waste management options, resulting in a reduction of 2.5% to 9.5% (Espinoza-Orias 12).
In conclusion, the carbon footprints of home-made sandwiches are generally less than the carbon footprints of ready-made sandwiches. According to the results of the study, the average impact of a home-made sandwich is 2.2 times lower than a ready-made sandwich with the exact same ingredients. However, both home-made and ready-made sandwiches have room for improvement to lower their carbon footprint and greenhouse gas emissions. Next time that you are looking for a sandwich, consider the ingredients and the carbon footprint of that sandwich, as it might be better for the Earth if you make the sandwich yourself instead of purchasing it pre-made and reduce your carbon footprint.