Characterisation of phenolic extracts from olive pulp and olive pomace by electrospray mass spectrometry

Methanol extracts of olive pomace (two-phase olive oil extraction) and olive pulp were analysed by reverse phase HPLC and the eluted fractions were characterised by electrospray ionisation mass spectrometry. This technique allowed the identification of some common phenolic compounds, namely, verbascoside, rutin, caffeoyl-quinic acid, luteolin-4-glucoside and 11-methyl-oleoside. Hydroxytyrosol-1'-beta-glucoside, luteolin-7-rutinoside and oleoside were also detected. Moreover, this technique enabled the identification, for the first time in Olea europaea tissues, of two oleoside derivatives, 6'-beta-glucopyranosyl-oleoside and 6'-beta-rhamnopyranosyl-oleoside, and of 10-hydroxy-oleuropein. Also, an oleuropein glucoside that had previously been identified in olive leaves was now detected in olive fruit, both in olive pulp and olive pomace. With the exception of oleoside and oleuropein, the majority of phenolic compounds were found to occur in equivalent amounts in olive pulp and olive pomace. Oleoside was the main phenolic compound in olive pulp (31.6 mg g(-1)) but was reduced to 3.6 mg g(-1) in olive pomace, and oleuropein (2.7 mg g(-1) in the pulp) almost disappeared (<0.1 mg g(-1) in the pomace). Both these phenolic compounds were degraded during the olive oil extraction process. (C) 2004 Society of Chemical Industry.