Optimization of Process Conditions for Pectin Extraction from Citrus Peel

Pectin is a complex polysaccharide and natural food additive extracted from citrus peel and apple pomace in the form of brownish powder. It is widely used as a jelling and thickening agent and the food industry especially in jams and jellies. It is also recommended for use as fat replacer and also lowers blood cholesterol by increasing viscosity in the intestinal tract thus lowering cholesterol absorption. Peel of sweet oranges was chopped to small pieces in a vegetable cutter and dried in an electrical drier to 8-10% moisture contents. The dried peel was ground and then subjected to pectin extraction using water as solvent. Three treatments with different levels i.e., pH (1, 2, 2.5, 3, 3.5, 4, 4.5 and 5), temperature of solvent (70, 85 and 95°C) and extraction time (0.5, 1, 2, 3, 4 and 5 h) were evaluated. Development of an economical processing method for pectin extraction from citrus peel, that offers energetic properties nearly identical to those prepared by other methods (soxhlet method and microwave) using other substrates, is reported. Dried citrus peel contains about 30% pectin It has been found that 30 min heating at 70°C and pH level 2.5 resulted in 21% pectin extraction followed by 1 h heating at 85°C at pH level 3.0 and a similar pectin yield. Up to 17% yield was obtained for heating at 95°C at pH level 1 irrespective of the time of heating. It can be inferred from these experiments that pH range between 2.0-2.5 and heating at temperature of 70°C for 30 min seems to be the most suitable condition for pectin extraction as time and energy efficient process conditions.