Method validation for Cafestol and Kahweol quantification in coffee brews by HPLC-DAD

Abstract

Cafestol and kahweol are two diterpenes exclusively found in coffee. Negative effects on health, like the increase in total lipid blood levels as well as positive effects like carcinogenic protective and antioxidant activity, have been reported for these two compounds. A simple and expeditious method for the quantification of total cafestol and kahweol levels in coffee brews by high-performance liquid chromatography with diode array detection was developed and validated. Esterified diterpenes were hydrolysed and resulting diterpene alcohols extracted with diethyl ether. For cafestol limit of detection was 0.01 mg L-1 and limit of quatification was 0.04 mg L-1. Coefficient of variation for cafestol ranged between 0.2 and 2.8 % for repeatability and between 1.4 and 15.3 % for intermediate precision. Average recoveries of cafestol-spiked coffee samples were from 96 to 110 %. Kahweol was quantified using cafestol calibration data and corrected by an appropriate conversion factor. Different kinds of coffee brews were analysed. Cafestol levels ranged from 0.04 to 0.80 mg/cup and for kahweol levels were between 0.01 and 0.40 mg/cup. Highest levels of diterpenes per cup were present in espresso coffee, while the lowest were found in filter coffee and instant coffee.