Cold brew coffee has soared in popularity among small and large commercial brewers, which often tout its health benefits. However, little research exists on the chemistry of this new coffee trend, said Megan Fuller, PhD, assistant professor of chemistry at Jefferson (Philadelphia University + Thomas Jefferson University).
To fill this gap, Fuller and Niny Rao, PhD, assistant professor of chemistry, explored the importance of brewing time, roasting temperature and grind size in cold brew coffee in the Dec. 21 issue of Scientific Reports. The East Falls faculty members studied cold and hot brew coffees made from a single source bean found in the Kona region of Hawaii, as well as analyzed medium and dark roast beans at medium and coarse grinds.
“Caffeine was studied for obvious reasons, but we also wanted to evaluate the concentration of 3-chlorogenic acid (3-CGA),” Fuller said. “This molecule represents a family of compounds known to act as antioxidants, which correlate to significant health benefits to coffee drinkers, such as decreased occurrence of depression, diabetes mellitus and certain types of cancers.”
They found the suggested brewing time of 10 to 24 hours outlined in typical cold brew methods doesn’t result in additional caffeine and 3-CGA concentration. Their research indicates that six to seven hours of brewing captures all the caffeine and 3-CGA available in the coffee grinds. In addition, they discovered 3-CGA and caffeine at higher concentrations in cold brew made with medium roast rather than dark roast. Coarse grind cold brew coffee also contained significantly more caffeine than the hot brew counterpart.
For future research, Rao and Fuller will work to understand the pH and total acidity of cold and hot brew coffees and the relationship between pH, total acidity and the antioxidant activity of coffee.