Enzymatic Hydrolysis of Used-Frying Oil Using Candida rugosa Lipase

Hydrolysis of used-frying oil had been carried out by using an immobilized lipase from Candida rugosa in solvent-free system. Used-frying oil was considered as the substrate in this study due to abundance amount of used-frying oil present in Malaysia as its disposal problem has become a very serious environmental issue.  The high free fatty acids (FFA) content in used-frying oil has raised the interest for the utilization of this waste into valuable products. Even though used-frying oil is not suitable for human consumption and being extensively used for the biodiesel production, FFA from used-frying oil could be utilized to produce various types of non-edible products. Effects of enzyme loading, water content, reaction temperature, buffer pH and agitation speeds on the hydrolysis process were investigated. The experiments were conducted at constant reaction time of 3 hours. It was found that the effect of variables were very significant on the hydrolysis process.  The hydrolysis process achieved the highest yield of fatty acids at enzyme concentration of 1.5% (w/v), buffer volume to oil volume ratio of 3:1, temperature of 40˚C, pH of 7, and agitation speed of 220 rpm. Under these described conditions, it was found that nearly 97.15±1.31% of hydrolysis degree was achieved with 2533.33±26.67 µmol/ml of fatty acids was produced.