Kinetics modeling for the extraction of phenolic compound from palm kernel cake using microwave-assisted method

Abstract. This study investigates the influence of microwave heating power and extraction time on the extraction of total phenolic content (TPC) from palm kernel cake (PKC). Additionally, it explores the antioxidant activity (AOA) of the extracted TPC under various microwave heating powers. Microwave-assisted extraction (MAE) is utilized as a non-conventional method for phenolic compound extraction, offering benefits such as reduced extraction time, minimal solvent usage, cost-effectiveness, and simplicity, while achieving high TPC and AOA yields. The parameters for microwave extraction include extraction times of 10, 15, 20, and 25 minutes, and microwave power of 300, 450, and 600 W. The TPC and AOA were analysed using UV-vis spectrophotometer at wavelength of 765 nm and 517 nm respectively. The highest TPC and AOA obtained were 1.715 mg GAE/g dry oil and 186.03 g AAE/mL respectively at 25 minutes and 300 W while the lowest TPC and AOA were 0.931 mg GAE/g dry oil and 99.68 g AAE/mL respectively at 10 minutes and 600 W. Low level of DPPH correlates with lower absorbance at 517 nm that indicates high scavenging activity, and consequently, greater antioxidant activity. FTIR study reveals that the phenol component of both the extracted and pure solid PKC is visible in the wavenumber region of 3500–3200 cm–1. Finally, from the kinetic study, at 600 W of microwave power, the second-order extraction rate constant, k, was 0.6292 Lg-1min-1, the extraction capacity (Cs) was 1.0761 gL-1, and the greatest coefficient of determination, R2 was 0.9782.