ENZYME ASSISTED AQUEOUS EXTRACTION OF VEGETABLE OIL AND EVALUATION OF ITS PHYSICOCHEMICAL AND NUTRITIONAL PROPERTIES

Abstract

Edible oils are among the most abundant cooking ingredients in the world and form a big sector of the food industry. Soybean, sunflower, rape and palm oil account for more than 70% of vegetable oils. Solvent method of extraction is the most common method employed at the industrial scale for extraction of vegetable oil. This method, however, has a lot of disadvantages from health hazard to environmental pollution being the primary. Aqueous enzymatic extraction of vegetable oils has recently gained popularity. This method is environmentally clean and poses no health hazard. The study was done to optimize the process parameters of aqueous enzymatic extraction to enhance the oil yield and identify the change in physicochemical properties of the oil before and after treatment with oil. Process parameters like enzyme dosage, G-force, and rotor type were optimized to obtain maximum oil yield. Soxhlet was run using hexane as solvent to identify losses in the waste stream i.e. sludge and fiber. The oil obtained after the enzymatic treatment was assessed for its free fatty acid content and deterioration of bleachability index. Other properties like carotene content and total moisture content was also analyzed. Effect of heat on oil quality was also analyzed by quantifying free fatty acids after subjecting oil to 90οC for five hours. Role of exogenous lipases in deteriorating oil quality was assessed by adding a lipase at 100ppm, 50ppm and 5ppm and then determining the FFA generated. Enzyme A1 (higher dose), 9600 G-force, and swing out rotor were identified as the best fit giving maximum oil yield. Soxhlet run showed that after enzyme addition, oil losses were significantly reduced in the waste stream leading to more oil yield in the product. Microscopic analysis of the sample revealed cell wall degradation and release of the oil droplet in the surrounding environment. The FFA was relatively same in oil derived from enzymatic and non-enzymatic method. FFA value was seen to rise slightly and then become stable after subjecting the oil to 90οC for five hours. The DOBI value, however, showed a sharp decline. 100ppm concentration of lipase upon addition showed a sharp increase in FFA content while 50ppm and 5ppm dosages had FFA content similar to the control sample.