No abstract

No abstract

Lipase-catalysed interesterification of palm stearin with soybean oil in a continuous fluidised-bed reactorThe aim of this study was the interesterification of palm stearin with soybean oil, catalysed by a commercial immobilised lipase from Candida antarctica, in a continuous fluidised-bed reactor. The interesterification was indirectly followed by the decrease in the solid fat content at 35 7C (SFC 35 7C ). The best reaction conditions were previously established batchwise via response surface methodology as a function of temperature and medium composition. The reactor operated continuously for 21 days. During the first 16 days, no significant decrease in the initial activity was observed and a reduction of 30-40% in the SFC 35 7C was achieved. Subsequently, a progressive decrease in the activity was detected, and a reduction of only 5% in the SFC 35 7C was obtained after 21 days of operation. The biocatalyst could be partially reactivated and was reused, under the same conditions, for a further period of 21 days. A similar inactivation profile, described by a series-type inactivation kinetics model, was observed. The estimated values for the half-life and the deactivation coefficient were the same for the fresh and reactivated biocatalyst (17 days and 0.0035 d 22, respectively). The free fatty acid content of the interesterified fat in the continuous reactor (0.7-1.2%) was lower than that of the fat obtained batchwise (2-6%).

Modelling lipase-catalysed transesterification of fats containing n-3 fatty acids monitored by their solid fat contentTransesterification 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 7C, 20 7C, 30 7C and 35 7C.A decrease in all SFC values of the blends at 10 7C, 20 7C, 30 7C and 357C was observed upon transesterification. The SFC 10 7C and SFC 20 7C of transesterified blends varied between 18 and 48 and SFC 35 7C 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.

No abstract