Drying Kinetics of Deglet Enour Date Seeds, Antioxidant, Antibacterial, Antidiabetic and Bio-preservative Potencies
摘要
The effect of four drying temperatures (50, 60, 70 and 80 °C) on drying kinetics, colorimetric parameters, the total phenol, flavonoid, tannin and carotenoid contents and antioxidant activities of date seeds extract (water- acetone- ethanol, v/v/v) was investigated. Drying at 60 °C is the most suitable to preserve color and antioxidants of date seeds. The extract of date seeds dried at 60 °C had the highest phenol (6.6 ± 0.09 g GAE/100 g DM), flavonoid (5.64 ± 0.14 g QE/100 g DM), tannin (9.73 ± 0.16 g CE/100 g DM) and carotenoid contents (0.65 ± 0.002 mg β-carotene E/100 g DM). The extract of date seeds dried at 60 °C shows an interesting α-amylase inhibition and antibacterial activities against eight foodborne pathogens and this was associated to its richness in epicatechin and procyanidin identified by UHPLC-DAD-ESI/MS. The potential bio-preservative activity of the extract, at different concentrations was confirmed in UHT- cow milk matrix model, inoculated with Staphylococcus aureus and monitored for 7 days at 4 °C. Moreover, the addition of 50 and 100 mg/mL of dried date seeds extract showed good overall acceptability scores of non-inoculated milk. The addition of 50 mg/mL of dried date seeds extract significantly (p < 0.05) increased the total phenols, the total flavonoids and enhanced the antioxidant potency of non-inoculated milk.