Characterization of pomegranate peels tannin extractives

The phenolic extractives of pomegranate peels from various cultivars were studied. The total polyphenols, the condensed and the hydrolyzable tannin contents were analyzed for 4 Tunisian pomegranate cultivars (Mekki, Chelfi, Gabsi, Jbeli). Matrix assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry was used to examine the tannin oligomer structure. Analysis shows fluctuating rates of total polyphenols, condensed and hydrolyzable tannins between the different cultivars, but they are considered higher than those found with other plants.Flavonoid oligomers up to pentamers and some hexamers were detected in MALDI-TOF positive ion mode analysis. In the negative ion mode analysis the majority of the oligomers have glucose residues linked to them.

The potential use of pomegranate peels extract as phenol substitutes was studied. The total phenols, the condensed tannins and the hydrolyzable tannins contents were analyzed for four Tunisian pomegranate cultivars (Mekki, Chelfi, Gabsi, Jbeli). Matrix assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry was used to examine the tannin oligomer structure. Analysis shows fluctuating rates of total polyphenols, condensed tannins and hydrolyzable tannins between the different cultivars, but they are considered higher than those found with other plants. Flavonoid oligomers up to pentamers and some hexamers were detected in MALDI positive ion mode analysis. In the negative ion mode analysis the majority of the oligomers have glucose residues linked to them.Figure optionsDownload as PowerPoint slideHighlights
► The pomegranate peels has been identified as a source of tannins.
► Fluctuating phenolic contents from 10 to 18% depending on cultivars, has been observed.
► We have also observed strong differences between hydrolysable and condensed tannins concentrations.
► We have identified four types of condensed tannins by MALDI-TOF analysis.