Pectin extraction from citron peel: optimization by Box-Behnken response surface design

In this study, the effect of acidic extraction conditions (time of 30-90 min, temperature of 75-95 A degrees C and pH of 1.5-3) on the yield and degree of esterification (DE) of citron peel pectin was investigated applying Box-Behnken design. The highest production yield of pectin (28.31 +/- 0.11%) was achieved at extraction time of 90 min, temperature of 95 A degrees C and pH of 1.5, as optimal extraction conditions, which was close to the predicted value (29.87%). Under optimum extraction conditions, the DE and the emulsifying activity were 51.33 and 46.2%, respectively. In addition, the emulsions were 93.9 and 93.5 stable at 4 A degrees C, 93.7 and 93.1 at 23 A degrees C after 1 and 30 days, respectively. The determination of flow behavior showed that the pectin solutions had a Newtonian behavior at low concentrations (< 1.0% w/v), while this behavior was changed to pseudoplastic with increasing concentration.