Optimisation of ultrasonic-assisted extraction conditions of Citrus hystrix for the total phenolic content

The total phenolic compound is a huge contributor to antioxidant activity. Natural antioxidants provide no side effect to the user and is a better option as compared to synthetic antioxidant. This paper studied the single-factor optimisation of ultrasonic-assisted extraction (UAE) conditions of Citrus Hystix, also known as Kaffir Lime for the total phenolic content (TPC). The selected parameters to study were raw materials to solvent ratio (1:10 to 1:30), solvent concentration (40% to 80%), extraction temperature (30°C to 70°C), ultrasonic power (40% to 80%) and extraction time (30 min to 90 min). The extraction solvent used was ethanol and the TPC was tested using Folin-Ciocalteu method. The optimum levels of the UAE conditions were identified through single-factor analysis. Based on experimental results, the optimum raw materials to solvent ratio was 1:30, solvent concentration was 70%, extraction temperature was 50°C, ultrasonic power was 60% and extraction time was 45 min. Based on single-factor analysis, the most significant factor was raw materials to solvent ratio and the least significant factor was the extraction time.