The effect of preharvest factors on bio-active components of date fruits (Phoenix dactylifera L.)

Date palm exposed to various agro-ecological factors causes a modification of synthesis, transport, and accumulation of certain bio-active compounds. The aim of this study is to evaluate agro-ecological factors responsible for the variation of bio-active dates. To achieve this, estimations were carried out on 12 samples of ‘Aziza Bouzid’ from the oasis of Figuig. We also studied preharvest practices, including irrigation, fertilizers and different bunch fruits practices. ANOVA results showed a significant variation between different samples. The high level of total content of phenols and flavonoids was recorded for dates sampled taken from Hamam Tahtani Ht (total phenolic content (TPC) = 201.79 mg gallic acid equivalent (GAE) 100 g^‑1 dry weight, total flavonoid content (TFC) = 132.73 mg quercetin equivalent (QE) 100 g^‑1 dry weight); however, the lowest values were total phenolic content (TPC) = 100.61 mg gallic acid equivalent (GAE) 100 g^‑1 dry weight and total flavonoid content (TFC) = 62.10 mg quercetin equivalent (QE) 100 g^‑1 dry weight, respectively for Znaga 2 (Zng 2). Correlation analysis of antioxidant capacities and TPC content showed a high correlation (IC₅₀ of DPPH scavenging activity r²=-0.771 and FRAP activity r²=0.752). Total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of the studied fruits may be conditioned by the bunch management technique used by farmers, such as bagging thinning, which can promote light penetration into the fruit. The identification of the main factors influencing the phenolic compounds of dates would improve their medicinal and antioxidant properties.