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.