The longer it takes to brew a batch of beer, the greater the chances of microorganisms getting in and ruining the whole thing. In order to speed up and simplify the process, scientists have developed tiny BeerBots.
When making beer, brewers start by extracting sugars from grains such as barley, resulting in a solution known as wort. Yeast is then added to the wort, where it ferments the sugars and thus converts them into alcohol and flavor compounds.
The fermentation process takes up to four weeks, during which time bacteria may get into the wort and ultimately spoil the flavor of the beer. Additionally, once the process is complete, all of the yeast cells must be filtered out of the beer, which is a time-consuming task.
That's where the BeerBots come in.
Created by Prof. Martin Pumera and colleagues at the University of Chemistry and Technology Prague, the devices take the form of 2-mm-wide beads. Each bead is made by mixing active yeast, magnetic iron oxide nanoparticles and sodium alginate, then dripping the liquid mixture (one drop at a time) into a ferric chloride solution. In a final step, one side of each bead is made porous by exposing it to an alkaline solution within an electrochemical cell.
When the resulting BeerBots are dropped into a flask of wort, they initially sink to the bottom. As they start fermenting sugars, however, they produce carbon dioxide bubbles which propel them up to the surface.
There, the bots release carbon dioxide gas into the air, before sinking back down again. They repeat this up-and-down process until all the sugars in the wort have been fermented. The beads then stay on the bottom of the flask, where they can be collected and removed using a magnet – that process is reportedly much quicker and easier than filtering out free yeast cells, which take longer to ferment the sugars.
As an added bonus, it was found that individual batches of BeerBots could be reused in up to three more fermentation cycles before needing to be discarded.
All of that being said, Pumera tells us that the technology would be difficult to scale up to industrial use in its present form, so it may end up being utilized mainly by small-scale craft beer producers.
A paper on the research was recently published in the journal ACS Nano.
Source: American Chemical Society
