BeerBots developed for faster brewing

Researchers have come up with a way of speeding up the beer-brewing process with beer-making mini-bots or ‘BeerBots’. Published in ACS Nano, the study shows that these self-propelled, magnetic packages of yeast can make the fermentation phase go faster and cut out the need to filter the beverage.

Beer, one of the world’s most consumed drinks, can take a while to brew. During the first step, sugars are extracted from grains to make a watery solution called wort. Yeasts then ferment those sugars, converting them into alcohol, carbon dioxide gas and new flavour compounds. This step can take up to four weeks and, during that time, unwanted microorganisms can get in and spoil the product with sour flavours.

Previous research has suggested that encapsulating the yeast in polymer capsules could reduce the risk of spoilage by speeding up the process, leading Martin Pumera and colleagues to developing the BeerBots.

The researchers made 2-mm-wide BeerBot capsules by combining active yeast, magnetic iron oxide nanoparticles and sodium alginate from algae and dripping the mixture into a ferric chloride solution. Then they made one side of the spheres porous by exposing that half to an alkaline solution in an electrochemical cell.

Initial experiments showed that the yeast-containing beads could ferment sugar and produce carbon dioxide bubbles that propelled them upward. When they got to the surface, they released carbon dioxide into the air and then sank again, resulting in a bobbing motion. When used to ferment malted barley wort, the team found that the self-propelled BeerBots transformed sugars faster than free yeast cells.

As the sugar was used up and fermentation ceased, the yeast-containing capsules sank to the bottom of the flask. This made it easy to separate the yeast from the final product with a magnet, rather than with a filtration step that’s currently required to remove free yeast cells. Additionally, the collected BeerBots were active for up to three more wort fermentation cycles. The results showed that BeerBots could produce brews faster.

Image caption: Self-propelled ‘BeerBots’ bob up and down as they ferment sugars to produce beer. Image credit: Adapted from ACS Nano 2023, DOI: 10.1021/acsnano.2c12677