Optimization of pectin extraction from orange juice waste assisted by ohmic heating

Ohmic heating is an alternative fast and uniform heating which can extract biomaterials more efficiently than the conventional heating from plant cell walls. Central Composite Design: was employed to study the effect of voltage gradient, temperature and time on the yield, galacturonic acid content and degree of esterification of the pectin. Results: showed that the highest yield of pectin (14.32 g/100 g d. m.) was obtained at the optimum conditions including voltage gradient of 15 V/cm, temperature of 90 degrees C during 30 min and was significantly (p < 0.05) higher than the pectin yield obtained by conventional method (13.53 g/100 g d. m.). The emulsifying activity of the pectin extracted under the optimal conditions was 67.18 +/- 3.77% which was similar to those obtained from the pectin extracted by conventional heating. In addition, the emulsions were maintained 91.88 to 94.87% stable after 30 days of storage. The flow behavior of the optimal pectin solutions at concentration of 0.5% w/v was the Newtonian, while at higher concentration (2% w/v), pseudoplastic flow was observed.