If you want to make the best possible cup of coffee to start your day, a new study suggests that you may want to put your coffee beans in the freezer for more a flavorful experience. Any coffee connoisseur knows that your brew is only as good as the beans you use, but how you store said beans can compromise taste as well. Coffee beans should be kept away from heat, light, and moisture, but whether or not beans need to be refrigerated for freshness is still up for debate. The National Coffee Association recommends that for the best taste, beans should be stored in an airtight container at room temperature. And if you can’t trust the National Coffee Association, who can you trust?
Now, the discussion is heating up, as a group of scientists from the University of Bath working with a local coffee shop owner have concluded that keeping the beans extra cold won’t just keep ‘em fresh, but will improve flavor as well. The study, which was published in Scientific Reports, found that grinding cold beans can improve to two aspects of coffee compounds that are thought to influence flavor — particle size and particle size distribution.
Scientists found when the beans are cold they grind more evenly, and the particles tighten up at lower temperatures, releasing more coffee-ness when brewed. Of course, many factors are coming into play when hot water splashes and bubbles over those grounds releasing that comforting aroma such as water chemistry, and surface area of the coffee. Every time we groggily stumble over to our coffee machine and flip the switch we are essentially chemists (one thing caffeine addicts can feel good about).
To test the effects of grinding beans at differing temperatures, researchers stored whole roasted Guatemalan coffee beans at four temperatures: in liquid nitrogen, a tub of dry ice, on the countertop, and in a freezer. After two hours, the beans were immediately put in the grinder before any change in temperature could occur or condensation could gather. They found that cold beans ground more uniformly, which allowed more surface area in the brewing process, and thus the extraction of more flavor.
"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," Christopher Hendon, who is getting his chemistry PhD at the University of Bath, told Gizmodo. "So you would have to brew it for less time or could get more coffee from the same beans." Co-author and owner of the cafe Colonna & Smalls, Maxwell Colonna-Dashwood, believes this study could have major implications for the coffee biz. “All of this will impact on how we prepare coffee in the industry," she told Gizmodo. "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." She posits that once this new information spreads, baristas may choose to brew coffee differently and producers may choose to ship their beans at lower temperatures.
Of course, if you are freezing your beans at home be sure to keep them in a truly airtight container for no more than a week, as freezer burn and other foods can change the coffee's flavor. And if, like me, you are too lazy to grind beans yourself at seven AM for a caffeine fix, just keep on doing what you're doing.