A new analytical method for the simultaneous quantification of isoflavones and lignans in 25 green coffee samples by HPLC-MS/MS

Green coffee, the raw material of roasted coffee and coffee beverages, is one of the most widely traded commodities worldwide. There is a dearth of studies on its content in phytoestrogens such as isoflavones and lignans. Previously, we developed an efficient method for the simultaneous quantification of 6 isoflavones (daidzin, genistin, daidzein, genistein, formononetin and biochanin A) and 3 lignans (secoisolariciresinol, matairesinol and lariciresinol) in green coffee by using HPLC-MS/MS. Several extraction processes were evaluated and the best performing, base hydrolysis followed by enzymatic digestion, was validated and used to analyse 25 different coffee samples, 1 Coffea canephora and 24 Coffea arabica, from different countries. Lignans (total content: 286.5–8131.8 μg kg−1) were found in higher concentration than isoflavones (total content: 3.4–300.0 μg kg−1) and the most abundant were secoisolariciresinol (172.6–5714.1 μg kg−1) and lariciresinol (113.9–2417.7 μg kg−1). Notably, the Ethiopian coffee samples contained the highest levels of these compounds.