Lipase-mediated hydrolysis of flax seed oil for selective enrichment of α-linolenic acid

Polyunsaturated fatty acids (PUFA) are important ingredients of human diet because of their prominent role in the function of human brain, eye and kidney. alpha-Linolenic acid (ALA), a C18, n-3 PUFA is a precursor of long chain PUFA in humans. Commercial lipases of Candida rugosa, Pseudomonas cepacea, Pseudomonas fluorescens, and Rhizomucor miehei were used for hydrolysis of flax seed oil. Reversed phase high performance liquid chromatography followed by gas chromatography showed that the purified oil contained 12 triacylglycerols (TAGs) with differences in fatty acid compositions. Flax seed oil TAGs contained alpha-linolenic acid (50%) as a major fatty acid while palmitic, oleic, linoleic made up rest of the portion. Among the four commercial lipases C. rugosa has preference for ALA, and that ALA was enriched in free fatty acids. C. rugosa lipase mediated hydrolysis of the TAGs resulted in a fatty acid mixture that was enriched in alpha-linolenic to about 72% yield that could be further enriched to 80% yield by selective removal of saturated fatty acids by urea complexation. Such purified ALA can be used for preparation of ALA-enriched glycerides. Practical applications: This methodology allows purifying ALA from fatty acid mixture obtained from flax seed oil by urea complexation.