Leveraging leftovers: Researchers unlock tech to extract protein from beer brewing waste

18 Apr 2024 --- As the F&B industry grapples with food waste, scientists in Singapore have tapped into a technology to extract 80% of the available protein from beer-brewing leftovers known as brewers’ spent grain (BSG). The protein extraction helps reduce waste and is used in protein enrichment for plant-based foods and in dairy, bakery foaming and gelling applications.

BSG is the most significant byproduct of the beer brewing industry and contributes to 85% of the total waste. Globally, about 36.4 million tons of spent grain are produced yearly, typically discarded after its primary use in brewing beer. 

While some efforts are made to repurpose BSG in applications such as animal feed, biofuel production or composting, a substantial portion still ends up in landfills, generating greenhouse gasses. 

But microwave-assisted three-phase partitioning (MATPP) provides another opportunity to recycle the historically discarded BSG.

“The most significant side-streams in Asia would be BSG and soybean residues (Okara). We aim to retrieve nutritional values from BSG and Okara and reconnect these to the food value chain to enhance the efficiency of the current food system and reduce environmental contamination,” professor William Chen, lead author of the research and director of Nanyang Technological University (NTU), Singapore’s Food Science and Technology (FST) program, which conducted the study, tells Food Ingredients First.

“Our initial motivation was to develop technology platforms to upcycle food processing side-streams which are considered waste-to-be as these usually are either channeled to animal farms as feed or end up in the landfills.” 

In 2020, Asia produced 550.88 billion hL of beer along with 11.018 million tons of BSG the same year, he highlights. In Europe, the figures were 550.93 billion hL of beer and 10.019 million tons of BSG.

Mitigating protein shortage
The researchers, who extracted up to 200 g of protein from one kg of BSG, indicate its potential as a protein source at a time when the Singapore Health Promotion Board recommends 40 g of protein for women and 56 g for men per day.

NTU’s brewers’ spent grain and the extracted protein powder for plant-based foods to boost their nutritional profile (Image credit: NTU).“BSG proteins recovered from our approach are easier to absorb and digest as they have been reduced to smaller sizes by the fermentation and enriched in micronutrients including antioxidants and vitamins produced by the microbes used in the fermentation,” notes Prof. Chen.

The proteins can enhance the nutritional quality of plant-based protein foods, which “tend to have lower levels of proteins and are lower in protein quality” (depending on the source).

“Demonstrating that the protein-rich qualities of BSG could be successfully extracted and funneled 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.”

The study, published in Innovative Food Science and Emerging Technologies also flags the “apparent major issue faced by humanity” — the lack of proteins to feed the world in the near future. Consumption of animal proteins contributes 40% to the global protein intake and is expected to increase by 73% by 2050 due to the growing population.

Conventional meat production is “no longer practical” to meet the demand of the 10 billion world population in 2050, states the study, adding that the pressure has triggered the development of sustainable proteins from various alternative sources, such as plants, microorganisms and insects.

Speeding up natural protein production
The current protein extraction methods employed by the food industry are time-consuming and involve processes that use high amounts of chemicals and expensive equipment, resulting in high total costs for the purified products, Dr. Chai Kong Fei, senior research fellow at NTU’s FST program and first author of the study, tells Food Ingredients First.

Brewers’ spent grain (BSG) is the solid residue from malted barley after brewing beer.He stresses the need for rapid, environmentally-friendly, cost-effective and scalable approaches for extracting proteins from natural sources.

“MATPP is an emerging non-chromatographic bioseparation technique capable of simultaneously extracting and separating BSG protein. Initially, BSG undergoes fungal fermentation to increase the solubility of its protein fractions before being subjected to MATPP for protein extraction,” he explains.

The method recovers BSG protein in a relatively short time frame (less than an hour) compared to conventional methods that may take more than three hours, he reveals.

He believes the method has significant potential for industrial-scale utilization due to its cost reduction potential, recyclable chemicals, efficiency and easy scalability.

Food fortification and foaming 
Prof. Chen advocates the protein extraction method’s value proposition in the existing food production system, after applying the fermentation technology to soybean residues and BSG.

“The fermented okara and BSG can replace the culture medium of yeast microalgae and cultivated meat with a huge cost reduction (up to 90%). Recently, we have demonstrated that the protein part of the fermented BSG has emulsifier properties and can replace the egg yolk in mayonnaise.”

He also shines a light on the protein’s applications in the F&B industry. 

The BSG protein can be used in meat analogs for texturization.“Extracted proteins find various applications in fortification (into dairy, bread or other processed food for enhanced nutritional benefits), texturization (for meat analogs), emulsification (alternative source for animal-sourced emulsifiers), foaming (to make food/drinks flavor more volatile for enhanced palatability) and gelling (leading to targeted/optimal texture of the food products).”

Toward efficient food systems
As consumer concerns toward environmental causes deepen, Prof. Chen observes an inclination toward sustainable foods.

“Consumers are showing an increasing awareness of the need for an efficient food system (zero waste processing and food circular economy) and cost-efficient or sustainable future food systems (alternative protein industry and higher nutritional values).”

“Our past and present innovations have been well received by industry and consumers alike. These are reflected in the number of our IPs being licensed to industry and the number of joint labs and collaboration agreements we have signed with the food industry,” he concludes.

In the future, the scientists are looking to work with industry partners to scale up their innovations and integrate the protein extracted from BSG and other side-streams into the food value chain for enhanced nutritional benefits.

By Insha Naureen