Caffeine extraction from Arabic coffee: The role of brewing and roasting

Abstract

Objectives: The global population's primary intake of caffeine comes from the consumption of coffee. Arabic coffee is traditionally brewed and served using a unique process. The objective of this study was to examine the plausibility of two widespread myths regarding Arabic coffee; that the longer the cooking time, and/or the more roasted the coffee, the higher is the amount of caffeine extracted per kilo-gram of raw coffee (CE). Materials and Methods: A total of 12 different samples of traditionally brewed Arabic coffee (with correction of lost volume due to evaporation) were directly analyzed for their caffeine concentration using the ultra-high performance liquid chromatography. The amount of caffeine extracted per kilogram of raw coffee (CE) where then calculated. Comparisons were then made between the CE from three types of raw coffee beans; Yemeni Bari, Yemeni Kulani, and Ethiopian Harrari. They were each roasted to two different grades (light vs. medium-dark) and each grade was cooked for a different duration of time (15 min vs. 30 min). Results: The type of coffee bean used was shown to significantly affect the amount of CE from raw coffee (P = 0.011). The highest amount of caffeine was extracted from raw Ethiopian Harrari coffee bean, followed by the Yemeni Kulani bean (P = 0.020 and P = 0.027, respectively). A longer cooking time significantly decreased the amount of CE from raw coffee as compared to a shorter time (P = 0.041). Medium-dark roasting was observed to cause a slight but nonsignificant decrease in amount of CE compared to light roasting (P = 0.178). Conclusions: The type of coffee bean used in brewing Arabic coffee is the main determinant of the amount of caffeine extracted from raw coffee. Longer cooking time and a darker roast both decrease the amount of extracted caffeine in the final brew, rendering the old myths nonplausible.