Evaluation of Egyptian pomegranate cultivars for antioxidant activity, phenolic and flavonoid contents

Abstract

Aim The aim of the present study was to evaluate total phenolic and flavonoid contents as well as antioxidant activity of the peel, juice and seed extracts of pomegranate fruit from different Egyptian cultivars. The selected cultivar was subjected for evaluation of the effect of peel homogenate on volatile compounds in juice supplemented with this homogenate. Background Pomegranate fruit is a rich source of natural antioxidants; it has wide applications in food and pharmaceutical industry. Materials and methods Five cultivars of Egyptian pomegranate were subjected to a comparative study of phenolic and flavonoid contents as well as its antioxidant activity. The phenolic compounds were determined through high-performance liquid chromatography, and the volatile compounds of selected cultivar peel were added to juice through gas chromatography and gas chromatography–mass spectrometry. Results While the total phenolic content varied between 5.21 mg gallic acid equivalent/g in PG4 fruit juice and 17.24 mg gallic acid equivalent/g in PG1 peel, the total flavonoid content ranged from 9.64 in PG2 juice to 34.28 mg rutin/g in the peel of PG1. All peel, juice and seeds extracts exhibited high antioxidant activities, evaluated using 1,1’-diphenyl-2-picrylhydrazyl and β-carotene assays. Gallic acid, chlorogenic acid and caffeic acid were the predominant phenolic compounds of the pomegranate cultivars. A total of 17 volatile compounds were identified, including six monoterpenes, three monoterpenoids, three aldehydes, three esters, and two alcohols. Conclusion Peel, juice and seed of Egyptian pomegranate cultivars contain significant amounts of phenolics and flavonoids contents. However, the peel contains higher contents compared with juice and seeds. Peel homogenate of the selected cultivar showed a remarkable effect on volatile compounds when used for fortification of the pomegranate juice.