Observation of Differences in Bioactive Compounds and Biogenic Element Content of Elaeagnus (Elaeagnus angustifolia L.) Fruit Harvested at Different Maturity Stages

The amounts of total phenol and flavonoid of Elaeagnus flowers and fruit collected at different maturity stages were between 234.94 (18 August) and 922.62 mg GAE/100 g (1 August) and 73.93 (4 October) and 525.36 mg/100 g (flowering stage), respectively. The antioxidant capacity of Elaeagnus flowers and fruit was between 3.57 (30 October) and 12.16 mmol/kg (1 August). While the total phenol and antioxidant capacity of the samples was at the highest levels in the first flowering period and the second harvest period, it decreased significantly in the other harvest periods. Gallic acid and 3,4-dihydroxybenzoic acid values of Elaeagnus fruit collected at different maturity stages were between 4.29 (flowering stage) and 130.29 mg/100 g (3 September) and 1.13 (3 September) and 13.42 mg/100 g (4 October), respectively. The P and K values of fruit samples were between 374.89 (20 November) and 2125.18 mg/kg (flowering stage) and 4348.70 (20 September) and 10158.48 mg/kg (flowering stage), respectively. In general, there was a significant decrease in the majority of the phenolics of Elaeagnus fruit harvested on 30 October. The gallic acid content of Elaeagnus increased significantly after the flowering phase. In general, the protein and mineral contents of buckthorn fruit were detected at very high levels in the first three periods of harvesting, while they decreased significantly at other times. The element with the highest concentration in Elaeagnus fruit was K, followed by Ca, P, S, Mg, Fe, Mn, Zn, B, and Cu in decreasing order.