Evaluation of l-phenylalanine ammonia-lyase activity and phenolic profile in olive drupe ( Olea europaea L.) from fruit setting period to harvesting time

Abstract

During the olive drupes ( Olea europaea L.) development we have observed significant correlations ( r = 0.82, r = 0.82 and r = 0.64 for Arbequina, Farga and Morrut varieties) between l-phenylalanine ammonia-lyase enzymatic activity (PAL, EC 4.3.1.5) and the olive drupe phenolic content. l-Phenylalanine ammonia-lyase activity and the total phenol content in olive drupes suffered a decrease when the maturation processes began. Total phenol content decrease could be used as a differential since it decreased regularly in the Arbequina cv. during maturation, while their content in the Farga and Morrut cv. underwent an important decrease due probably to high variability on ripening index of Arbequina variety. Oleuropein could be used as maturation parameter at harvesting period since in Morrut and Farga cv. showed ten and six times more oleuropein than Arbequina cv. It also could be used as a maturation parameter luteolin and luteolin-7-glucoside, which had higher values in Arbequina cv. (653–62 mg kg −1, respectively) than in Farga (222–25 mg kg −1) and Morrut cv. (201–not detected mg kg −1) at harvesting period. The data obtained during the fruit development indicate than phenol content and composition, in particular oleuropein, luteolin and luteolin-7-glucoside will be useful for biochemical characterisation of olive drupes of different O. europaea L. varieties.