Researchers believe so-called BeerBots can speed up the brewing process.
Dr Martin Pumera, of Czech Republic’s Brno University of Technology, and colleagues wanted to develop a self-propelled bot to both make fermentation proceed faster and simplify the separation of yeast from the final beer.
Reporting in ACS Nano, the team 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.
The two-millimetre-wide robots are made of iron oxide and contain yeast to supercharge the fermentation process.
When they have finished their mission of swimming around in the fermenting container they can be removed with a magnet, avoiding having to add a filtering process.
The beer fermentation process can take as long as four weeks. During that time, unwanted microorganisms can get in and spoil the final product with sour flavours.
Previous researchers have suggested that encapsulating the yeast in polymer capsules could lessen the chance of spoilage by speeding up the process. However, Dr. Pumera and colleagues wanted to develop a self-propelled bot to both make fermentation proceed more quickly and simplify the separation of yeast from the final beer.
The researchers made the tiny 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.
Based on these results, the researchers say that BeerBots could produce tasty brews faster.
The study ‘Nanostructured Hybrid BioBots for Beer Brewing’ was published in ACS Nano.
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