Abstract

The production of a cocoa butter equivalent (CBE) through enzymic interesterification of palm oil midfraction (POMF) with stearic acid in a solvent free system using Novo lipase Lipozyme™ as a catalyst was analyzed. A two level factorial design was used to study the effect of the initial ratio of stearic acid-POMF, initial humidity of the enzyme preparation and the enzyme-substrate ratio on the yield, mass productivity and specific productivity. Studies were carried out both in batch and in a continuous packed bed reactor. The highest specific productivity obtained in shake flask was 0.0393 g/Batch Interesterification Unit (BIU) h at a stearic acid-POMF ratio of 1.6 and enzyme-substrate ratio of 23 BIU/g. In the continuous packed bed reactor the highest mass productivity observed was 1.54 g/g·h, using an enzymic load of 73 BIU/g. Unreacted fatty acids were separated from the intereresterified products by short path distillation at 0.2 mbar and 140°C obtaining a product practically without free fatty acids. Thermograms of the products obtained by scanning differential calorimetry were similar to cocoa butter (CB), but exhibited several distinct peaks, due presumably to the presence of diglycerides and trisaturated triglycerides. © 2001 Elsevier Science Ltd.