Factors affecting tocopherol contents in coffee brews: NP-HPLC/FLD, RP-UPLC-ESI/MSn and spectroscopic study

Qualitative and quantitative determination of tocopherols in filtered and unfiltered coffee brews was investigated. The NP-HPLC/FLD and RP-UPLC-ESI/MSn techniques as well as fluorescence spectroscopy turned out to be very useful tools not only to estimate tocopherol contents, but also to detect contaminants in coffee brew tocopherol extracts. In all analysed coffee brew samples, only alpha- and beta-T were detected. In Arabica coffee brews, the content of the beta homologue was three to four times higher than that of the alpha homologue; however, in Robusta, they were almost identical. Unfiltered coffee brews contained about ten times more tocopherols, 3.02-5.26 and 3.39-16.52, than filtered brews, 0.4-0.71 and 1.26-1.77 mu g/100 ml for alpha-T and beta-T, respectively. The reduction in the size of ground coffee beans from 0.7 to 0.3 mm increases the concentration of tocopherols almost three times. Suspended coffee bean dust was the main source of tocopherols in coffee brews.