The effect of cultivar variation on total phenolic contents and antioxidant activities of date palm fruit (Phoenix dactylifera L.)

Abstract

© 2020 The Author(s). Published by Enviro Research Publishers. Date palm fruit (Phoenix dactylifera L.) is generally consumed in form of dry fruits (Tamr stage); however, fresh date palm fruit in Khalal stage is currently of interest due to its high total phenolic contents (TPCs) and antioxidant activities. Therefore, this study aimed to investigate the water based extraction conditions such as temperature (30-90°C), shaking time (0.5-6 hours) and solid-to-liquid ratio (100-500 mg/mL) of date palm fruit in Khalal stage. This will help to establish extraction protocol for future food applications. Under optimized extraction conditions, TPCs and antioxidant activities of cell culture originated (CO) and seed originated (SO) date palm fruit were compared to examine the effect of cultivar variation. The results suggest that optimization of extraction conditions was reached using the concentration of 100 mg/mL, extraction temperature of 50°C, and shaking time of one hour. Under these extraction conditions, CO exhibited TPCs of 3.47±0.33 mg GAE/g DW as well as antioxidant activities of 0.0025±0.00, 16.13±0.81 and 123.21±9.77 μmol TE/g DW measured by DPPH radical scavenging, FRAP and ORAC assays, respectively. Interestingly, SO exhibited higher TPCs (3.87±0.23 mg GAE/g DW) and antioxidant activities (0.0021±0.00, 19.23±0.80 and 185.68±9.29 μmol TE/g DW by DPPH radical scavenging, FRAP and ORAC assays, respectively).The findings from this study will promote consumption of date palm fruits in Khalal stage as healthy food and support its future development for food. Also, this will enhance the growth of date palm fruit with its attendant economic benefits.