The world’s population is expected to grow by more than 40% by 2050. Sustainably feeding the growing world is going to be a global effort, one that is no easy feat. According to research from Wageningen University, we need to change both our consumption behaviour and our means of food production. Food waste should be minimised and a large proportion of our diet should come from plant-based products.
While the importance of protein in the diet is well-established, ensuring that the expected world population of 10 billion in 2050 has access to adequate amounts of protein, sourced sustainably, means looking further afield and beyond conventional meat.
Researchers from Singapore’s Nanyang Technological University (NTU), may have come up with a method to help address this dilemma by extracting edible protein from brewers’ spent grain, a byproduct of brewing beer. Their findings were published in the Innovative Food Science and Emerging Technologies journal.
Lead author of the study and director of NTU's Food Science and Technology programme, William Chen, said: "Our method presents an innovative way to repurpose beer waste into a valuable protein source for global nutrition.”
Protein successfully extracted from brewers' spent grain
The researchers developed a sustainable method of extracting protein from brewers’ spent grain. In doing so, they were able to extract 80%of the available protein, up to 200 g of protein per kilogram of brewers’ spent grain . Globally, approximately 36.4 million tonnes of brewers’ spent grain are produced yearly. If 200 g of protein per kilo were to be extracted from this waste, it would amount to approximately 7.8 billion kilos of protein.
Before extracting the protein, the team used hizopus oligosporus, a food-grade fungus, to sterilise the brewers’ spent grain . Next, a three-day fermentation process took place, which assisted in breaking down brewers’ spent grain ’s structure and making the protein easily extractable. The fermented brewers’ spent grain was then dried, before being ground into a powder, sieved, and spun in a centrifuge. The protein separated from the rest of the mixture in the centrifuge and floated to the top where it was extracted and was ready to be used.
"Our study, which presents more sustainable and efficient ways to add value to brewers' spent grain disposal, is a crucial step towards mitigating its contribution to greenhouse emissions and reducing environmental strain, while also enriching the global food supply chain,” said Chen. “Demonstrating that the protein-rich qualities of brewers' spent grain could be successfully extracted and funnelled into supplements and enriching plant-based proteins to make them more attractive to the consumer addresses two global pressure points – food wastage and food shortage."
Upcycled protein isolate could appeal to consumer demand for sustainable options
Consumers want sustainable options when it comes to food. According to the World Economic Forum (WEF) in 2023 around 65% of consumers wanted to make the right spending choices to live a more sustainable and healthier life. When it comes to the food industry, WEF suggested that food producers can appeal to evolving consumer appetites while looking after the planet, through a wider product range of sustainable goods.
Brewers’ spent grain contains around 19-30% crude protein, making it an ideal raw material for protein isolate production. One study compared the nutritional and functional characteristics of brewers’ spent grain protein isolate, with commercially available pea and soy protein isolates. In terms of nutrition, the researchers found that the spent grain isolate met or exceeded the requirements of each essential amino acid per g protein, except for lysine.
Similar protein contents were found across the three protein isolates, but the spent grain isolate exceeded the pea and soy versions in terms of protein solubility, which in turn affected other functional products of the spent grain isolate. It also exhibited high solubility, foaming capacity, and minimal gelation properties. The researchers concluded that their findings indicated spent grain isolate's potential as a new, sustainable plant-based protein source for human nutrition, particularly for dairy alternative applications.
