Forget Nitro Brew Coffee, Meet Nitro Bean

The perfect roast for your next cup of joe might just come from liquid nitrogen chilled coffee beans. A team from the University of Bath, working with the Bath coffee shop Colonna & Smalls, reports that chilling roasted beans before grinding results in small uniform coffee grinds. This provides for better extraction of flavor compounds, according to the researchers, and thus allows baristas to brew more coffee and get more flavor from the same amount of coffee.

“What you’re looking for is a grind that has the smallest difference between the smallest and largest particle,” says Dr Christopher Hendon, a chemistry PhD student at the University of Bath, at the time of the study, who now works at the Massachusetts Institute of Technology. “If you have small grinds you can push flavor extraction upwards. We found that chilling the beans tightens up this process and can give higher extractions with less variance in the flavor, so you would have to brew it for less time, or could get more coffee from the same beans.”

The team studied the effect of grinding beans at different temperatures, from room temperature down to -196°C, and discovered that the colder the beans the finer and more uniform the particles were from the grind. For the study, published in Scientific Reports, 20 g of whole roasted beans were stored in a covered paper cup before being cooled with either a standard freezer, dry ice or liquid nitrogen for two hours. The beans were then taken directly from these controlled temperatures to a grinder switched on five seconds before grinding the beans.

“Grinding coffee may seem quite straightforward,” says Maxwell Colonna-Dashwood, co-owner of Colonna & Smalls. “(You) break coffee up into a lot of tiny bits so you can dissolve it in water. But like the whole world of coffee the subtleties of the process have a huge impact on the flavor and quality of the cup of coffee. The ability to understand grinding more comprehensively has the dual impact of allowing us to make better tasting coffee and to be more efficient in the way we do that.”

The research suggests that bean temperature needs to be more constant to help brewers achieve consistent grinds. It also suggests that cooler temperatures will allow them to maximize surface area and utilize more of the coffee, potentially impacting how coffee is prepared and stored across the industry.

“I bet we will see the impact of this paper in coffee competitions around the globe, but also in the research and development of new grinding technology for the market place,” sayss Colonna-Dashwood.