Antioxidant activity and physico-chemical properties of Tunisian grown pomegranate (Punica granatum L.) cultivars

The objective of this study was to compare the physico-chemical characteristics and antioxidant activity of 13 pomegranate cultivars grown in southern Tunisia. Fruit size, skin color, skin thickness, juice yield, juice color, total soluble solids, pH, titratable acidity, total phenolics, total and individual anthocyanin and antioxidant activity were measured in the pomegranate cultivars. The results showed great differences in the characteristics and the composition of the pomegranate cultivars. The considerable variation was consistent with ANOVA and PCA results. Three cultivars were found isolated with particular characteristics; CH8-2 distinguished with large fruit size, MZ2 with red-colored peel, sour sweet juice and high antioxidant activity and GS1 with the smallest fruit, the lowest juice content, highest juice acidity and with its considerable antioxidant activity. In addition, the cultivar RF1was also detached from other cultivars with considerable amounts of phenolics and anthocyanins. Results showed also significant correlations between total phenolics content and antioxidant activity indicating the contribution of phenolic compounds in juice antioxidant capacity. Moreover, significant correlations were found between the red color intensity a* and antioxidant capacity, or total phenolic content and some anthocyanins pigments suggesting the richness of red juices in antioxidants, phenolic compounds and anthocyanin pigments. The correlation observed between the juice visual color and color indices of CIE L*a*b* emphasize the efficiency of the grading color scale to determine the color of pomegranate juice in the absence of the CIE system. These results would be a guide in the selection of potential cultivars which are used in food and chemical industry and fresh market. (C) 2012 Elsevier B.V. All rights reserved.