Abstract: In the present study, ultrasonic radiation was found to largely enhance the extraction of pectin from Promma microphylla Turcz leaves with ammonium oxalate solution. In order to further intensify pectin extraction, the ultrasonic-aided ammonium oxalate extraction process was optimized by orthogonal array design on the basis of a series of single-factor experiments. Under the conditions studied, temperature, length of extraction time, ammonium oxalate concentration and material-to-liquid ratio could affect pectin extraction differently, and the effects of ammonium oxalate concentration and temperature were significant, and the optimal conditions of the four parameters were 70 ℃, 70 min, 8 g/L and 50:1, respectively. Under these conditions, the extraction rate of pectin reached up to 63.79%. Furthermore, the quality indicators of the extracted pectin could meet the requirements of the industrial standard (QB 2484－2000).

Key words: Promma microphylla Turcz, pectin, ammonium oxalate, ultrasonic extraction, orthogonal array design