Lipase‐catalysed interesterification of palm stearin with soybean oil in a continuous fluidised‐bed reactor

The 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 °C (SFC35 °C). 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 SFC35 °C was achieved. Subsequently, a progressive decrease in the activity was detected, and a reduction of only 5% in the SFC35 °C 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−2, 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%).