Optimization of Pectin Xxtraction from Unriped Grape Pomace Using Citric Acid and Investigation of Its Physicochemical Properties

In this study, unrippen grape pomace as a valuable source for pectin extraction was investigated using acidic extraction method. For this purpose, Box-Behnken design with four independent variables in three levels (Time (30-90 min), Temperature (70-90℃), pH (1.5-3.0) and liquid to solid ratio (20-40 v/w)) was used to optimize the pectin extraction yield that the highest pectin extraction yield in the optimum conditions (time of  85 min, the temperature of 90℃, pH of 1.5 and liquid to solid ratio of 20 (v/w)) was 26.1 ± 1.0%. The results showed that unrippen grape pomace pectin had degree of esterification of 51.6%, galacturonic acid content of 66.1%, emulsifying activity of 57.2%, and also showed favorable emulsion stability. The FT-IR spectrum confirmed the presence of esterified poly galacturonic acid structure in pectin sample.