Vegan cheese struggles to compete with dairy products
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If you love cheese but feel guilty about its huge environmental impact, there is hope on the horizon. The milk protein that is most important for producing cheese and yoghurt has been made in bacteria for the first time, which could allow these products to be made directly from plants without any cows involved.
“It will significantly reduce the carbon footprint,” says Suvasini Balasubramanian at the Technical University of Denmark.
Dairy milk is a complex mix of many chemicals, but for cheese manufacture, the most important component is the globules, or micelles, made of proteins called caseins wrapped around calcium compounds.
After casein proteins are first produced in mammary gland cells, most have phosphate groups added to them, a process called phosphorylation. These phosphate groups interact directly with calcium and are essential for the formation of micelles.
While it is simple to get bacteria to make unmodified casein proteins, achieving phosphorylation has proved tricky. No one has managed to get the cow enzyme that phosphorylates caseins to work in bacteria. “This has been tried for a long time now,” says Balasubramanian. “All the start-ups and companies have been struggling.”
Her team has now succeeded in producing one kind of phosphorylated casein in E. coli bacteria by using bacterial enzymes. This casein does have a few more added phosphates than normal, but Balasubramanian points out that casein phosphorylation can vary from one breed of cattle to another. “I don’t think it will affect the functionality of the protein,” she says.
The researchers are now scaling up the process so they can try making cheese and other dairy products from the protein. It might work, Balasubramanian says, or it might turn out other types of casein are needed too – in particular, kappa casein, which is modified by the addition of sugars rather than phosphates.
Producing a kilogram of cheese currently emits around 24 kilograms of carbon dioxide or equivalents, compared with 100 kilograms for beef but well under 2 kilograms for most plant-based foods. The hope is that producing products such as casein using microbes – known as precision fermentation or cellular agriculture – will dramatically reduce emissions and other environmental impacts, as well as eliminate animal welfare issues.
The carbon footprint of cellular agriculture depends on what the microbes are fed on and the energy used during manufacture. Balasubramanian says her team is testing feedstocks derived from alfalfa grass.
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