Conventional and eco-friendly aqueous extraction methods of date palm fruit compounds: Optimization, comparison, characterization of the date pulp extract and value-added potential

The extraction of the total soluble solid compounds from the pulp fruit Phoenix dactylifera L. is a major challenge for their valorization in the date fruit industry. However, conventional aqueous extraction methods are limited in terms of efficiency and processing time. In order to optimize this process, this study explores and compares three extraction methods: microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), and conventional water bath–assisted extraction (WAE). The primary objective of this study is to maximize extraction recovery (ER) by performing an optimization using a Box–Behnken design (BBD). The second objective is to analyze the impact of the three extraction methods on extraction recovery, functional attributes, biochemical characteristics, antioxidant and antibacterial activities of the optimized date pulp aqueous extract (DPAE). Results obtained using mathematical models showed significant differences (p < 0.05) between the three methods tested. Optimum extraction conditions were determined as follows: for WAE, a solid/liquid (S/L) ratio of 1/4.68 g/mL, a temperature of 80 ℃, and a duration of 38.63 minutes; for MAE, an S/L ratio of 1/6 g/mL, an irradiation power of 480 W, and a duration of 11 minutes; for UAE, an S/L ratio of 1/5 g/mL, a sonication amplitude of 40%, and a duration of 60 minutes. The MAE method stood out for its extraction efficiency, with ER = 79.90% ± 1.54% and being three times faster than WAE and MAE. It also provided the highest concentrations of total soluble solids (14.33% ± 0.11% FW), total sugars (22.23 ± 0.23 g/100 mL DPAE), and total polyphenols (1.69 ± 0.04 mg GAE/mL DPAE). The antioxidant activity of DPAE was high, with an IC₅₀ of 729.80 ± 12.87 μg/mL of the methanolic extract. These results suggest that the optimization of extraction processes, particularly using microwave technology, could offer promising prospects for the valorization of date fruit products by improving the production efficiency of a natural and nutritious DPAE, potentially beneficial to the date fruit industry in terms of product quality and cost reduction.