BurgAir: A microbial meat alternative burger for a food-secure future

Ayesha Izzati, Brigitta Kinara, Devangana Mallik, Rajalakshmi Narasimhan, Kaitlyn Schenkeveld and Ana Timpano

Degree:
- Bachelor of Applied Science
Program:
- Chemical and Biological Engineering
Campus: Vancouver

Our project

Our project brings together our interests in chemical and biological engineering, environmental impact and food. Plant-based meat alternatives like soy require significant land and water, and remain tied to traditional agriculture. We came across a NASA-funded project that used gases to produce a protein powder and were inspired about the idea of using microorganisms that feed on carbon dioxide, hydrogen and oxygen to make food, without the need for soil or sunlight.

That idea became BurgAir. We designed a process plant that uses Xanthobacter, a hydrogenotrophic bacterium, to convert hydrogen, oxygen and carbon dioxide — along with a liquid nutrient medium — into a nutrient-rich, shelf-ready burger patty.

Our final product contains 30 grams of protein per serving, which is 10 grams more than typical plant-based patties sold today. Additionally, the market opportunity is significant. The global meat substitute market is estimated at over US$18.5 billion today and is projected to reach US$225 billion by 2030.

Our design solution

Our process starts with preparing a liquid nutrient medium and introducing the gaseous feedstocks — carbon dioxide, renewable hydrogen and oxygen — into an air-lift bioreactor where Xanthobacter grows to a target concentration. Because our bacteria, liquid and gas form a three-phase system, we needed a bioreactor design that could handle high gas volumes without mechanical stirrers or baffles. The air-lift bioreactor uses the incoming gas streams themselves to provide mixing.

Once the bacteria reach the desired concentration, we separate the biomass from the liquid medium using a disc-stack centrifuge and then wash it twice to remove residual media.

The clean biomass slurry goes into a twin-screw extruder that transforms it into a meat analogue that is similar in structure to a tofu block. We then combine that with canola oil, coconut oil, salt and flavourings in a food mixer, form the mixture into patties and send it to packaging.

The proposed facility, which is located in Germany to take advantage of green hydrogen infrastructure, would yield 18 million BurgAir patties annually.

A key decision point that affected our design solution was deciding where to stop. Other companies use a similar gas fermentation processes to create a protein powder. We knew we wanted to go farther than that to create a ready-to-eat food product. While we briefly considered options like a protein bar, once we came up with the burger idea, we were all in!

How we validated our solution

BurgAir is a process design project. Although we came up with detailed designs for each step in our process, we did not produce an actual physical burger patty.

We grounded our calculations using existing industry data. Our growth parameters for Xanthobacter were drawn from a Finnish company that uses a comparable process to produce protein powder.

Our product formulation assumptions are based on standard food industry practice. We also received feedback from our professors to validate our assumptions and design the solution.

What we’re most proud of

Looking back at our very first meeting notes — when we were still trying to identify our topic — and comparing that to where we are now, we’re proud of the sheer scope of what we put together. None of us fully appreciated how much work it would take to go from defining a problem to producing a complete process design that includes economic and hazard analyses.

We’re also proud of how accessible our project is. Chemical and biological engineering can seem abstract to people outside the field, and there’s often the assumption that process engineers only work in specific traditional industries.

This project shows how we can apply our skills and knowledge to address some of the most significant issues of our time, such as climate change, food production and resource scarcity.

Finally, we’re proud of our ability to embrace the open-endedness of capstone itself.

In most undergraduate courses, problems come with defined boundaries and given variables. Here, we had to set those ourselves and draw on the knowledge we’d acquired throughout our degree. Capstone mirrors what a process engineer actually does in industry and it made everything feel very real.

What’s next for BurgAir

Our capstone project shows the proof of concept for BurgAir. The natural next step would be experimental validation: actually growing Xanthobacter at a small scale to confirm our assumptions.

However, our work points to the bigger picture that microbes can be used as a source of high-quality protein.

Instead of relying on animal protein or vegetable sources of protein — both of which contribute to climate change — we’ve shown how you can decouple food production from agriculture to create a shelf-ready product.