Ah, Christmas dinner. Lashings of juicy meat and over-cooked veg quaffed down with booze and trifle. Good for the soul, although perhaps not so great for your belt size, or for the environment.
Whilst Christmas day certainly isn’t the day to worry too much about your waistline, new research suggests that it could be a good day to consider your environmental footprint, particularly when it comes to thinking about how you’re going to cook your dinner.
“Our research found that our cooking practices could increase the impact of food items by up to 61 per cent, with oven usage the most impactful practice,” said Dr Ximena Schmidt, a Global Challenges Research Fellow at Brunel University London, who worked alongside colleagues from the University of Sheffield’s Institute of Sustainable Food, the University of Manchester and City University. “This is quite timely if we think about how Christmas dinners are cooked.”
The research, published in Nature Food, compared how different cooking methods affect the overall greenhouse emissions of particular types of food. They found that roasting food in an oven has the highest overall impact, whilst using a microwave has the lowest. In the cases of some food, such as tofu, changing the heating method could reduce a food’s cooking emissions by as much as 16-fold.
“Perhaps this year we might want to explore more sustainable cooking practices – for example, pre-cook food in the microwave or on the stove and then use the oven, or consider using energy saving appliances such as slow cookers or pressure cookers. If not for Christmas, it might be a nice new year's resolution!" said Dr Schmidt.
Professor Sarah Bridle from the University of Manchester, added: "A lot of people are thinking carefully about what type of food to eat, or how it's packaged or transported but, in terms of climate change, it is sometimes more important to consider how the food is cooked.”
Boiling and microwaving our Christmas dinners isn’t the most impactful path towards a sustainable festive meal however, with cutting out meat all together still being the single biggest change that people can make – a kilogram of farm-reared, oven-cook British beef can generate the equivalent of 643kg of carbon dioxide, more than a single flight from London to New York.
Project lead Dr Christian Reynolds, a visiting researcher at the Institute of Sustainable food and Senior Lecturer at the Centre for Food Policy, City University, said: “Our results underscore the importance of looking at the whole lifecycle of food when assessing the environmental impact of our supply chains, as consumption alone is such a significant contributor to the damage GHGs (greenhouse gases) do to the environment.
“We know GHG emissions from home cooking can be reduced by choosing which foods we eat and minimising cooking time and appliance use. Even combining a more environmentally friendly cooking method, such as using a microwave to part-cook food then roasting to finish in the oven, can cut our GHG emissions substantially.
“But for those not brave enough to try ‘boiling’ their turkey the fancy French way, investing in an electric pressure or slow cooker, both incredibly energy efficient ways to cook but still not widespread in the UK, can have a similar result and substantially reduce the environmental impact of more traditional cooking practices.
“Just pop the roast in the slow cooker on its ‘low’ setting with some water and cook for eight hours. Best to start on Christmas Eve though so you don’t forget!”
Three festive tips for a low-emissions Christmas
Reduce your meat consumption
A kilogram of beef protein reared on a British hill farm can generate the equivalent of 643 kg of carbon dioxide, but a kilogram of lamb protein produced in the same place can generate even more at 749 kg, mostly due to their long oven-roasting cooking times.
Dr Reynolds doesn’t suggest throwing out the whole turkey, however, as the good news for traditionalists is that turkey creates less GHG emissions than other types of meat, so is still a better choice for Christmas dinner. Of course, trying one of the many meat free alternatives now available has an even bigger impact.
Reduce your food waste
Is a whole turkey required? Maybe not for a small family, but one solution is to keep portion sizes small, with minimal left overs, and try not to be too ambitious with the number of dishes made as food waste also has a major impact on environmental damage.
Dr Reynolds suggests purchasing smaller mini-roasts or turkey crowns and split portions of dark and light meat as smaller roasts also cook faster, lowering the environmental impacts of roasting meat in an oven.
Reduce the time you spend cooking
It's not just the food, it's also how you cook it that affects GHG emissions, with ovens being the worst culprits of the kitchen, mostly due to the long cooking times and high-energy demands involved in roasting meat.
Reducing cooking time can help reduce GHG emissions. Part-cooking some foods in a microwave first can decrease the time required to cook food in the oven without substantially affecting the taste or texture. The research found that the impacts of cooking in a microwave, steaming and boiling are comparable for reheating, defrosting and preparing vegetables, fruits, eggs and fish, whilst preserving more of the water-soluble vitamins and minerals.
There is also a way you could half the environmental impact of roasting a turkey on Christmas Day. ‘Sous vide’, which means “under vacuum” in French, involves placing the roast in a vacuumed plastic pouch or bag, and submerging it in a heated water bath for eight hours until the internal temperature of the joint is between 55°C (white meat) to 75°C (dark meat). The roast is then unwrapped and placed in a hot skillet to sear its surface., preserving the texture and flavour.
Tim Pilgrim, Media Relations
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