Characterization and quantification of fruit phenolic compounds of European and Tunisian pear cultivars

- Polyphenol contents vary depending on pear fruit tissue and cultivar.
- Polyphenol concentrations in pear peel are up to six times higher than in the flesh.
- Procyanidins are the major phenolic compounds in pear flesh and peel.
- Tunisian dessert pears contain very highly polymerized procyanidins (DPn > 100).
- Perry pears are richer on procyanidins with intermediate degree of polymerization.

The flesh and peel of 19 pear cultivars (8 Tunisian dessert cultivars, 8 European dessert cultivars and 3 French perry pear cultivars) were studied for their phenolic composition. Phenolic compounds were identified by HPLC/ESI-MS2 and individually quantified by HPLC-DAD. Five classes of polyphenols were present: flavan-3-ols, phenolic acids, flavonols, anthocyanins and simple phenolics (hydroquinones). The total phenolic content ranged between 0.1 g/kg Fresh Weight (FW) ('Conference' cultivar) and 8.6 g/kg FW ('Plant De Blanc' cultivar) in the flesh and between 1.6 g/kg FW ('William vert' cultivar) and 40.4 g/kg FW ('Arbi Chiheb' cultivar) in the peel. Procyanidins, analyzed after thioacidolysis, were the main phenolic compounds in all pear cultivars either in the pulp or the peel, their constitutive units being essentially (−)-epicatechin. Tunisian dessert pears and French perry pears are richer in procyanidins with very high degree of polymerization (> 100) for Tunisian pears. Peel procyanidins were less polymerized (from 4 to 20). Pear peel phenolic profile was more complex especially for Tunisian cultivars, with flavonols and in some cultivars anthocyanins.

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