Abstract:

Ultrasonic technique, cellulose preparation and ion exchange resin were separately adopted to extract pectin from pumpkin flesh prepared into powder. The three extraction techniques were optimized by orthogonal array design, and validity of optimized conditions was verified triply. Additionally, effectiveness of these techniques was compared in terms of pectin yield. The optimal conditions for ultrasonic-assisted extraction were as follows: ultrasonic power 400 W, liquid/material ratio 10:1 (ml/g), extraction duration 35 min, and under these conditions a average pectin yield of 5.98% was achieved; the enzymatic extraction technique achieved an average yield of 9.56% under the optimized conditions as follows: enzymolysis duration 2.0 h, pH 4.5, temperature 55 ℃, and cellulase dose 0.5%; the optimal cation exchange resin (type 732) dose, material/liquid ratio (g/ml), pH, extraction duration, and temperature for extraction of pectin were 15%, 1:20, 2.5, 2.0 h, and 80 ℃, respectively, and under these conditions average yield of pectin was 7.62%. The results showed that compared to the other two extraction techniques cellulose-catalyzed hydrolysis is the most effective approach for preparing pectin from pumpkin.

Key words: pumpkin pectin, ultrasonic-assisted extraction, cellulase-catalyzed extraction, ion exchange resin extraction