PILOT BATCH-PRODUCTION OF SPECIFIC-STRUCTURED LIPIDS BY LIPASE-CATALYZED INTERESTERIFICATION - PRELIMINARY-STUDY ON INCORPORATION AND ACYL MIGRATION

Effects of water content, reaction time, and their relationships in th e production of two types of specific-structured lipids (sn-MLM- and s n-LML-types: L-long chain fatty acids; M-medium chain fatty acids) by lipase-catalyzed interesterification in a solvent-free system were stu died. The biocatalyst used was Lipozyme IM (commercial immobilized lip ase). The substrates used for sn-MLM-type were fish oil and capric aci d, and medium chain triacylglycerols and sunflower free fatty acids fo r sn-LML-type. The observed incorporation with the time course agrees well with the Michaelis-Menten equation, while the acyl migration is p roportional to time within the range of 20 mol% acyl migration (MLM-ty pe: M-f-0.2225T; R-2 = 0.98; LML-type: M-f= 0.5618T, R-2 = 0.99). As w ater content (wt%, on the enzyme basis) increased from 3.0 to 11.6% fo r MLM-type and from 3.0 to 7.2% for LML-type in the solvent-free syste ms, 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 mig ration 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 b y the different chain length of the fatty acids. The relationships bet ween reaction time and water content are inverse and give a quantitati ve prediction of incorporation and acyl migration in selected reaction conditions and vice versa. The acyl migration can not be totally avoi ded 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 discusse d.