Abstract: This study aimed to obtain the optimum conditions for the extraction of free amino acids from the flesh of Canarium album fruits by the combined use of one-factor-at-a-time method, Plackett-Burman design, steepest ascent design and response surface methodology. The results showed that the effects of factors on the extraction yield of free amino acids were in the descending order of solid-to-liquid ratio > number of extraction cycles > ultrasonication time > ultrasonic power > ethanol concentration > temperature, and the optimum levels of these variables were determined to be 20 min, 1:41 (g/mL), 3, 50 ℃, 270 W and 60%, respectively. Under these conditions, the predicted extraction yield of free amino acids was 77.84 mg/g while the actual value was 79.88 mg/g. The relative error was 2.62%, indicating that the optimized extraction method was reliable.

Key words: Canarium album, free amino acids, ultrasonic-assisted extraction, response surface methodology, Plackett-Burman design, Box-Behnken design