Increasing n-3 polyunsaturated fatty acid content of fish oil by temperature control of lipase-catalyzed acidolysis

An attempt was made to further increase the content of n‐3 polyunsaturated fatty acid (n‐3 PUFA) of fish oil by lipase‐catalyzed acidolysis (reaction between fish oil and n‐3 PUFA‐enriched free fatty acid) without solvent. A bioreactor system was constructed composed of a water‐jacketed packed‐bed column and a substrate reservoir with a circulation pipeline between the packed‐bed column and the reservoir. By keeping the temperature of the reservoir at −10°C (for the first 20 h), followed by −20°C (for the subsequent 40 h) during the batch acidolysis, crystals of free fatty acid appeared, which were removed intermittently by a cotton plug packed in the tip of the outlet pipe in the reservoir. The n‐3 PUFA content of the triacylglycerol fraction increased a further 10% by the reduced temperature of the reservoir.