Modelling lipase-catalysed transesterification of fats containing n-3 fatty acids monitored by their solid fat content

Transesterification of fat blends rich in n-3 polyunsaturated fatty acids (n-3 PUFA), catalysed by a commercial immobilised thermostable lipase from Thermomyces lanuginosa, was carried out batch-wise. Experiments were performed, following central composite rotatable designs (CCRDs) as a function of reaction time, temperature and media formulation. Mixtures of palm stearin, palm kernel oil and a commercial concentrate of triacylglycerols rich in n-3 PUFA ("EPAX 2050TG" in CCRD-1 and "EPAX 4510TG" in CCRD-2) were used. The time-course of transesterification was indirectly followed by the solid fat content (SFC) values of the blend at 10 degreesC, 20 degreesC, 30 degreesC and 35 degreesC. A decrease in all SFC values of the blends at 10 degreesC, 20 degreesC, 30 degreesC and 35 degreesC was observed upon transesterification. The SFC10degreesc and SFC20degreesC of transesterified blends varied between 18 and 48 and SFC35degreesC between 6 and 24. These values fulfil the technological requirements for the production of margarines. Under our conditions, lipid oxidation may be neglected. However, the accumulation up to 8.3% free fatty acids in reaction media is a problem to overcome. The development of response surface models, describing both the final SFC value and the SFC decrease, will allow predicting results for novel proportions of fats and oils and/or a novel combination time-temperature.