Development of an extraction method for the quantification of lignans in espresso coffee by using HPLC-MS/MS triple quadrupole

Lignans are polyphenolic compounds that are considered phytoestrogens for their plant origins and they possess different biological activities. Three different extraction methods, i.e., ‘dilute and shoot’, acidic hydrolysis and enzymatic digestion, have been compared for extracting lignans (secoisolariciresinol, SECO, matairesinol, MAT and lariciresinol LARI) from espresso coffee (EC) by using high performance liquid chromatography (HPLC) tandem mass spectrometry (MS/MS). The best recovery values (SECO: 97%, LARI: 98% and MAT: 93%) were obtained by using enzymatic hydrolysis with Clara-Diastase at 10% (w/v), keeping the sample at 37 °C for 3 hours. For this reason, this method has been chosen and then applied to quantify lignans in nine different EC samples from five different geographical origins (Brazil, Colombia, El Salvador, Ethiopia and India). SECO and LARI were found in all EC samples from 27.9 to 52.0 μg l-1 and from 5.3 to 27.8 μg l-1, respectively, contrary to MAT that it was not possible to detect it in each type of coffee. This method confirms the high specificity and sensitivity of MS/MS system for detecting bioactives in complex matrix such as coffee.