Optimization of aqueous pectin extraction from Citrus medica peel

In this study, the effect of aqueous extraction conditions (temperature of 70-90 °C, time of 60-180 min, and liquid/solid ratio (LSR) of 20-40 v/w) on the yield and degree of esterification (DE) of Citrus medica peel pectin was studied using a Box-Behnken design. The highest production yield of pectin (21.85 ± 0.35%) was obtained at temperature of 90 °C, extraction time of 180 min and LSR of 40 v/w as optimum extraction conditions which was close to the predicted value (24.13%). In these extraction conditions, the DE and the emulsifying activity were 77.2 and 46.5%, respectively. Also, the emulsions were 90.30 and 90% stable at 4 °C, and 83.87 and 83.50% at 25 °C after 1 and 30 days, respectively. The determination of flow behavior showed that the pectin solutions had a Newtonian behavior at low concentrations (0.1, 0.5 and 1.0%w/v), while in higher concentration (2.0%w/v), the pseudoplastic flow behavior became dominant.