Effect of pH, temperature and time of acidic extraction on the yield and characterization of pectin obtained from pumpkin waste

Seeded pumpkin is cultivated for its seeds to be used as snack. After removing seeds at harvest time, the residual including fruit peel and pulp are left in the field which causes pollution of the environment. The amount of wastage is considerable, thus it can be used as a pectin source. Pectin is an important structural constituent of plant cell wall. It is widely used as a gelling, thickening and stabilizing agent in food industries. In this study, pectin of seeded pumpkin was extracted under various conditions: pH (1, 2, 3 and 4), temperature (60, 75 and 90° C) and time (1, 2 and 3 hour). The extraction yield, degree of esterification and galacturonic acid of the extracted pectins were evaluated. In this study, yield of pectin was considerable and extracted pectins were high methoxyl pectins with high purity. The results showed that drastic condition of acidic extraction (lower pH, higher temperature and time) increased extraction yield and galacturonic acid content of pectin whereas it caused a decrease in the esterification degree of pectins. Analysis of variance showed that the temperature of extraction was the most significant factor on the pectin extraction yield while pH was the most influencing factor on the degree of esterification and galacturonic acid content of pectin.