ENZYME ASSISTED AQUEOUS EXTRACTION OF VEGETABLE OIL AND ENZYMATIC TREATMENT OF VEGETABLE OIL MILL EFFLUENT

Abstract

Vegetable oil represents a major share in the global consumable fats and oil produced. The major types of vegetable oil produced are Palm oil, Soybean oil, Canola oil etc. with palm accounting for more than 30% of the entire production. Conventional oil extraction steps include mechanical and solvent extraction. An alternative for these conventional steps of oil extraction is the aqueous enzymatic extraction, here the solvent used for extracting the oil is water and thus it minimises the many environmental hazards posed by solvent extraction. The enzymatic extraction involves use of a combination of hydrolytic enzymes to degrade the plant cell wall components and make the oil accessible for aqueous extraction. The major classes of enzymes include, cellulases, xylanases, proteases etc. This research work focuses on enzymatic aqueous extraction and its various parameter optimisation which include, dosage studies, oil loss analysis, and down streaming techniques like centrifugation. The dosage analysis shows the optimum dosage for effective enzymatic activity on the substrate. The enzymatic aqueous extraction is not as efficient as the solvent extraction hence oil loss studies are important to calculate the enzymatic efficiency, and this is done using Soxhlet analysis. Microscopic analysis of the substrate treated with enzyme is useful for understanding the enzymatic activity. The downstreaming of the extracted oil is also a vital step in getting higher oil yields and thus optimisation studies for centrifugation steps was carried out. These studies include, rotor type analysis and rcf value analysis for optimum oil yield. The effluent coming from the mills have high BOD and COD. The effluent is also rich in a lot of complex sugar polymers. Biogas production from effluent has an enormous potential in tackling various environmental problems including lowering greenhouse gas emission. The anaerobic digestion of effluent can be enhanced using the enzymes to break down complex polymers to soluble monomers that can be readily metabolized by methanogenic bacteria. The use of enzyme on effluent resulted in increase in the concentration of glucose and this was confirmed using DNS assay and HPLC. This further supports the idea of using enzymes in effluent treatment and suggests immense potential of enzymatic treatment of the effluent. Further research must be carried out for making this viable on an industrial scale.