DOI: https://doi.org/10.55373/mjchem.v27i1.158

Keywords: Rhizopus oryzae lipase; immobilised enzyme; biocatalyst; transesterification; cocoa butter alternative

Abstract

Rhizopus oryzae lipase (ROL) is a valuable biocatalyst for modifying oils and fats, especially in creating cocoa butter alternatives. However, its application in high-temperature industrial processes is limited by thermal stability. Also, water-restricted reactions like lipase-catalysed transesterification require a dried enzyme form. This study explored the use of immobilised ROL on sago, a porous and biocompatible support, for the enzymatic synthesis of structured lipids resembling cocoa butter. ROL was immobilised on sago using an optimised spray-drying method and applied in the transesterification of palm mid-fraction, olive oil, and stearic acid blends. The product developed using a 1:1:1 ratio emerged as the best cocoa butter alternative based on chemical and temperature analyses. High-performance liquid chromatography analysis of the enzymatic product showed reduced palmitoyl-oleoyl-palmitoyl glycerol and increased palmitoyl-oleoyl-stearoyl glycerol and stearoyl-oleoyl-stearoyl glycerol. Gas chromatography confirmed that stearic acid incorporation increased linearly with its molar ratio the reaction. The slip melting point of the synthesised alternative was 36.2°C, with solid fat content at 7.73 % at 30°C and 2.02 % at 40°C. Differential scanning calorimetry indicated two melting peaks below 37°C. This study highlights the successful use of immobilised ROL on sago to produce potential cocoa butter alternatives, advancing plant-based substitutes for the confectionery industry.