Deacidification of High Acid Olive Oil by Immobilized Lipase


Abstract: The acidity reduction of high acid oils prior to refining could be an attractive application for industry. In this study the enzymatic deacidification degummed and dewaxed olive oil with a high free fatty acid content, catalysed by an immobilized lipase was optimzed (Novozym 435). The optimum amount of substrate for synthesizing trigliycerides was the necessary stoichiometric amount of fatty acid and glycerol. The mixing was performed with a mechanical stirrer and the dehydration was performed by vacuum pump or by bubbling dry nitrogen. The dehydration rate was faster than the deacidification rate. The four parameters chosen for this experimental plan: pressure, temperature, and the amounts of glycerol and enzyme in the reaction mixture. The use of glycerol more than theortical amount did not affect the rate of deacidification. The stoichiometric amount of glycerol was sufficient for the deacidification of high acid olive oil. Maintaining low pressure is very important for the removal of water which is formed during the esterification reaction. Either, the reaction is conducted at 20 mm Hg or the dehydration is performed by bubbling dry nitrogen. The optimum amount of immobilized enzyme necessary for the deacidification reaction was determined and 10:1 ratio of oil: immobilized enzyme appeared to be satisfactory. The effect of temperature on the deacidification of high acid olive oil was investigated (between 40- 70^{\circ}C). The reaction temperature influenced the rate of deacidification. The optimum operation temperature was found to be 60^{\circ}C. At 70^{\circ}C the deacidification decreased with increasing incubation time due to enzyme deactivation occuring at this temperature.

Keywords: High acid oils, immobilized lipase, Biorefining, Enzymatic deacidification

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