Response surface optimization of ultrasonic‐assisted extraction of carotenoids from oil palm (Elaeis guineensis Jacq.) fronds

Oil palm (Elaeis guineensis Jacq.) fronds (OPF) are the most abundant oil palm solid wastes that are generated during oil palm agriculture and harvest. Palm oil and some other palm wastes have been reported to contain high concentrations of carotenoids with vital bioactive properties. However, the extraction and quantification of carotenoids from OPF have not been reported. In this study, ultrasonic‐assisted extraction, HPLC–FLD for quantification, and response surface methodology (RSM) for optimization of β‐carotene, lutein, and zeaxanthin from OPF extracts were investigated. The effects of extraction temperature (X (1): 30–70°C), extraction time (X (2): 10–50 min), and solvent–sample ratio (X (3): 10–50 mL/g) on the recovery of β‐carotene (Y (1)), lutein (Y (2)), and zeaxanthin (Y (3)) were investigated using three‐level Box–Behnken design (BBD) experiment. At a desirability of 1, the optimum extraction conditions for β‐carotene (30.14°C, 37.11 min, and 23.18 mL/g), lutein (30.00°C, 39.09 min, and 19.24 mL/g), and zeaxanthin (30.09°C, 36.76 min, and 22.38 mL/g) yielded carotenoid concentrations of 17.95 μg/g dry weight (DW), 261.99 μg/g DW, and 29.99 μg/g DW, respectively.