Nowadays, the consumers are reluctant against foods that contain chemical preservatives. Therefore, food manufacturers are turning their interest to their replacement with natural antioxidants. The pomegranate fruits (Punica granatum L.) are considered a good source of nutrients and antioxidants, that have been used for centuries as treatment for ulcer, hepatic damage and diabetes[1]. The health benefits of pomegranates have been attributed to the wide variety of bioactive compounds that are contained both in the fruits and their by-products (peels, seeds, etc.)[2]. Pomegranate’s peels are characterized by high content of polyphenols, such as condensed tannins and anthocyanins, while significant levels of phenolic content are detected in pomegranate seeds [3].
In the present study, different extraction methods were studied in order to retrieve the antioxidants of pomegranate by-products. Two green extraction processes were employed, the microwave assisted and the ultrasound assisted extractions, using water and ethanol as solvents. These extractions were carried out in fresh samples of by-products. In addition, conventional sequential extractions were carried out on dried samples, using solvents of different polarity (hexane, methanol, ethyl acetate, butanol, water). The extraction yield, as well as, the antioxidant activity of the extracts was evaluated. The antioxidant compounds of pomegranate have strong potential in scavenging free radicals and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used for their evaluation. According to this study, the pomegranate peel extracts has shown the greatest antioxidant activity among the by-products. The ethyl acetate extract of sequential extraction was found to have the greatest antioxidant activity, but low extraction yielding, while the water fraction showed satisfactory results. Moreover, both green extractions retrieved significant quantities of extract with good antioxidant activity.
References
[1] K.B. Ajaikumar, et al. Journal of Ethnopharmacology. 2005, 96 (1-2), 171-176.
[2] W.J. Qu, et al. Transactions of the ASABE. 2009, 52 (6), 1997–2006.
[3] W. Elfalleh, et al. Journal of Food Science. 2011, 76, 707–712.
