While competing claims and methodologies are being bandied about, one research team has been toiling away to nail down the carbon impact of products specific to bakers by developing a supply chain framework for measuring CO2 emissions from plough to plate. The results suggest that the bakery chain can operate at extremely high levels of efficiency, whether using animal or vegetable products and whether the products are organically-produced or not. But there is scope to improve energy efficiency in all parts of the food supply chain.

Wayne Martindale and Michael Jones of Sheffield Hallam University headed a recent project to develop a method for calculating CO2 emissions for the primary production and processing of bakery products, using recipe, processing energy and farm production data. The work used recipes from two catering companies and a national high street baker.


The project traced the supply chain of a number of high street bakery products, including a sausage roll, a strawberry tart and a ham and tomato sandwich. Researchers from the University’s Food Innovation Project calculated the carbon emissions in each stage of the recipes’ production. They took into account the growth and conversion of wheat grain and livestock to the baking, milling and drying of products, and finally the preparation of each recipe. The results show that the typical high street sandwich or sausage roll has a ’footprint’ of between 14 and 34g of CO2. It also found that:

l primary production emissions are always greater than processing and manufacturing emissions, suggesting resource efficiency improvement can be made at primary production levels;

l livestock products are more carbon dioxide-intensive. But products containing plant oils can significantly increase CO2 production emissions.

The project is now developing methods of accounting for distribution impacts. In many resource-efficient food supply chains, distribution CO2 emissions will be a relatively small part of a product’s total emissions. This naturally increases for imported and non-home-grown produce. Packaging emissions are also likely to be relatively low if the supply chain is resource-efficient.

Martindale says the project will investigate the relationship between carbon emissions and the health and wellbeing value of products: "We should all have the correct facts to make the choices we want when buying food. We’re privileged enough to be able to make those decisions in the UK - provided we are given that information."