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Second-grade dates ( Phoenix dactylifera L.), with hard texture, from six Tunisian cultivars were analysed for their composition and antioxidant activities. Results showed predominance of total sugars and a relatively low content of protein, fat and ash. On the other hand, optimisation of extraction of antioxidant was carried using five different solvents. The highest level of phenolic compounds for all dates varieties was found in the 70% acetone extract. This level ranged from 199.43 to 576.48 mg of GAE/100 g fresh weight. However, extraction into 50% methanol gave the highest antioxidant activity from 89.55 to 109.67 mg equivalents of ascorbic acid/g fresh weight. For both two solvents, Bejo exhibited the highest phenolic content and total antioxidant activity, while Baydh El Hamam presented the lowest. A positive linear correlation between total antioxidant activity and phenolic contents was observed ( R 2 = 0.83; R 2 = 0.74 for acetone/H 2 O and methanol/H 2 O, respectively). The antioxidant activity of acetone/H 2 O and methanol/H 2 O extracts was carried using DPPH radical-scavenging activity and reducing power. These results showed that dates had strongly scavenging activity on DPPH reaching 90.12% in methanol/H 2 O from Deglet Nour. Whereas, acetone/H 2 O showed the best reducing power which Bejo was significantly higher than the other varieties. This study demonstrates the potential antioxidant activity with Tunisian date, that we can use these natural extracts as food additives in replacement of synthetic compounds. |
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