Before attempting to identify the different levels of caffeine extracted through the various ways of processing coffee it is important to first understand…. what is caffeine? Per the definition published onwww.medlineplus.gov , “Caffeine is a substance that is found in certain plants. It can also be man-made and added to foods. It is a central nervous system stimulant and a diuretic (substance that helps rid your body of fluids).” Many people drink coffee to receive short-term relief from fatigue or drowsiness but despite the popular notion, it will not reduce the effects of alcohol.
When we first became interested in cold brew, the general consensus was cold brew coffee was significantly higher in caffeine than other brewed coffee methods (espresso, drip, etc). In some instances the caffeine in cold brew coffee was reported to be double to triple that of it’s hot brewed counterpart. The thought process was since cold brew coffee was steeped in water with a high ratio of coffee grinds to beans this made the resulting brew extremely high in caffeine. A recent study has shown this not to be the case.
One study entitled “The Effect of Time, Roasting Temperature, and Grind Size on Caffeine and Chlorogenic Acid Concentrations in Cold Brew Coffee”, published online 2017 Dec 21 on the National Center for Biotechnology Information website, examined four coffee samples (dark roast/medium grind, dark roast/coarse grind, medium roast/medium grind, and medium roast/coarse grind) using both cold and hot methods of brewing. The results of this study showed that higher concentrations of caffeine were found in cold brewed coffee made with medium roast coffees as opposed to the dark roast, grind size also played a role in caffeine concentrations as well. However, the amount of caffeine compared to hot brew coffee was not 2-3x the amount. See the chart below:
Given the study’s results, there is more caffeine extracted over 1440 minutes (Cold Brew brewing time) then a hot coffee extraction (done in minutes) but it is not 2-3 times as much. More like 1.x times as much. There is no constant given the variables of grind size, roast of the bean, and other variables such as steeping time, water, temperature, etc., so you cannot surmise a true average of caffeine in cold brew to hot brew. But using this study it is safe to say there is more caffeine in cold brew coffee, just not 2-3xs as much.
Fuller, Megan, and Niny Z Rao. “The Effect of Time, Roasting Temperature, and Grind Size on Caffeine and Chlorogenic Acid Concentrations in Cold Brew Coffee.”Scientific Reports, Nature Publishing Group UK, 21 Dec. 2017, www.ncbi.nlm.nih.gov/pmc/articles/PMC5740146/.