An international team of researchers has found that chilling roasted coffee beans before grinding results in narrower distribution of small particles, which during the brewing process allows access to more flavor from the same amount of coffee.
Brewing more flavorsome coffee could be as simple as chilling the coffee beans before grinding, say scientists. Image credit: Shixugang.
The research team, led by Dr. Christopher Hendon from the University of Bath, UK, studied the effect of grinding beans at different temperatures, from room temperature to minus 320.8 degrees Fahrenheit (minus 196 degrees Celsius), and discovered that the colder the beans the finer and more uniform the particles were from the grind.
“For temperature studies, we selected the Guatemalan coffee because this particular Guatemalan crop is representative of contemporary specialty grade coffee (i.e. it has a favorable balance of acidity, floral complexity and overall taste),” Dr. Hendon and co-authors explained.
“The four temperatures were achieved using the following method: 20 g of whole roasted coffee beans were placed into a paper cup, covered, and placed into: (i) liquid nitrogen, (ii) a tub of dry ice, (iii) the freezer and (iv) on the counter top.”
“The beans were equilibrated at each temperature for two hours prior to grinding.”
“What you’re looking for is a grind that has the smallest difference between the smallest and largest particle,” Dr. Hendon said. “If you have small grinds you can push flavor extraction upwards.”
The scientists found that chilling the beans tightens up this process and can give higher extractions with less variance in the flavor.
“It will alter the taste, because subtle changes in particle size distributions make a huge difference in rate of extraction,” Dr. Hendon added.
“It could have a major impact for the industry. People are trying to produce a very high quality drink with really quite powerful tools and are willing to try new things.”
“Grinding coffee may seem quite straightforward – break coffee up into a lot of tiny bits so you can dissolve it in water,” said co-author Maxwell Colonna-Dashwood, of Colonna & Smalls in Bath, UK.
“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 temperature of beans needs to be more constant to help us achieve consistent grinds.”
“It suggests that cooler temperatures will allow us to maximize surface area and utilize more of the coffee.”
“All of this will impact on how we prepare coffee in 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.”
The results are reported in a paper published online by the journal Scientific Reports on April 18, 2016.
_____
Erol Uman et al. 2016. The effect of bean origin and temperature on grinding roasted coffee. Scientific Reports 6, article number: 24483; doi: 10.1038/srep24483
