Evaluating effects of ellagic acid on the quality of kumquat fruits during storage

Abstract

To assess the preservative effects of the active ingredients in the leaves of Liquidambar formosana Hance, the present study assessed the antioxidant activity of ellagic acid using various antioxidant assays; 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid, 1,1-diphenyl-2-picrylhydrazyl, superoxide anion radical scavenging activity and reducing power. The results of these assays were combined with principal component analysis to analyze the effect of ellagic acid treatment on the overall quality of kumquat. Whole kumquat fruit were immersed in different concentrations of ellagic acid (0, 100 and 300 mg L−1) for 5 min, naturally dried then stored at room temperature (14–16 °C) for 18 days. During storage, the percentage weight loss and decay, firmness, total soluble solids, titratable acid and contents of malondialdehyde, superoxide dismutase and vitamin C were measured every 3 days. The results showed that, by 1,1-diphenyl-2-picrylhydrazyl scavenging activity and reducing power, the antioxidant activity of ellagic acid was more effective than butylated hydroxyanisole or ascorbic acid. Compared with untreated kumquat fruit, ellagic acid treatments can delay the decline in fruit firmness, total soluble solids, titratable acid and vitamin C contents, inhibit increases in malondialdehyde and enhance superoxide dismutase activity. The comprehensive evaluation of the results using principal component analysis was consistent with the experimental results, namely that ellagic acid treatment can significantly reduce the rate of deterioration in the quality of kumquat fruit, with the 300 mg L−1 treatment being better than the 100 mg L−1 treatment. The results show that ellagic acid has good prospects as a preservative treatment for kumquat fruit.