Chlorophyll and carotenoid pigments in the peel and flesh of commercial apple fruit varieties

Apple (Mains x domestica Borkh) has always been considered a fruit with low chlorophyll and carotenoid contents; however these pigments contribute also to the external (peel) and internal (flesh) fruit colourations, as well as to the health benefits associated with the regular consumption of this fruit. In the present work we studied the chlorophyll and carotenoid compositions of the peel and flesh of thirteen marketed apple varieties presenting different external colourations (green, yellow and red). All the varieties were characterised by a common pigment profile comprised by chlorophylls a and b, lutein, violaxanthin, neoxanthin, beta-carotene, and esterified carotenoids (mainly violaxanthin and neoxanthin) as major compounds. Total pigment content was always higher in the peel (58.72-1510.77 mu g/g dry wt) than in the flesh (14.80-71.57 mu g/g dry wt) for each particular cultivar. In general, the green cultivars showed the highest pigment content both in the peel and in the flesh, which were followed in decreasing order by the peel of some red-skinned cultivars and the flesh of the yellow ones. In most cultivars, a characteristic chloroplastic pigment profile was found in the peel, with lutein as the main free carotenoid whilst a chromoplastic profile was usually observed in the flesh, with a prevalence of violaxanthin and neoxanthin and their corresponding acyl esters (mono- and diesters). A correlation between the carotenoid content and the amount of esterified xanthophylls was observed, in particular in the flesh, which reinforce the putative role of the esterification process in the accumulation of these lipophilic compounds within the chromoplasts. (C) 2014 Elsevier Ltd. All rights reserved.