Pilot batch production of specific‐structured lipids by lipase‐catalyzed interesterification: Preliminary study on incorporation and acyl migration

Abstract

Abstract Effects of water content, reaction time, and their relationships in the production of two types of specific‐structured lipids ( sn ‐MLM‐ and sn ‐LML‐types: L‐long chain fatty acids; M‐medium chain fatty acids) by lipase‐catalyzed interesterification in a solvent‐free system were studied. The biocatalyst used was Lipozyme IM (commercial immobilized lipase). The substrates used for sn ‐MLM‐type were fish oil and capric acid, and medium chain triacylglycerols and sunflower free fatty acids for sn ‐LML‐type. The observed incorporation with the time course agrees well with the Michaelis‐Menten equation, while the acyl migration is proportional to time within the range of 20 mol% acyl migration (MLM‐type: M f =0.2225 T , R 2 =0.98; LML‐type: M f =0.5618 T , R 2 =0.99). As water content (wt%, on the enzyme basis) increased from 3.0 to 11.6% for MLM‐type and from 3.0 to 7.2% for LML‐type in the solvent‐free systems, the incorporation rates in the first 5 h increased from 3.34 to 10.30%/h, and from 7.29 to 11.12%/h, respectively. However, the acyl migration rates also increased from 0.22 to 1.12%/h and from 0.56 to 1.37%/h, respectively. Different effects in the production of two totally position‐opposed lipids can be observed. Presumably these are caused by the different chain length of the fatty acids. The relationships between reaction time and water content are inverse and give a quantitative prediction of incorporation and acyl migration in selected reaction conditions and vice versa. The acyl migration can not be totally avoided in present systems, but can be reduced to a relatively low level. Acyl migration during the downstream processing has also been observed and other factors influencing the acyl migration are briefly discussed.