Production and characterisation of cocoa butter equivalent from formulated hard palm oil midfraction and canola oil blends

Abstract

There has been increased interest in cocoa butter equivalent (CBE) due to high price, uncertainty in supply and variability in quality of authentic cocoa butter (CB). This study investigated the blending of hard palm oil midfraction (PMF) with canola oil to produce CBEs which contain omega-3 and omega-6 fatty acids using immobilized lipase from Rhizomucor miehei. The experiments were designed using Response Surface Methodology (RSM) to optimize the percentage of triacylgycerols (TAGs) including palmitic-oleic-palmitic (POP), palmitic-oleic-stearic (POS), stearic-oleic-stearic (SOS) and diacylglycerol (DAG). The experiment was performed at hard PMF concentration of 50 to 90%, lipozyme load between 5% and 10% with reaction time of 2 to 14 hours. The best reaction conditions to attain these targets were 58.85% of hard PMF concentration, 2 hours of reaction time and 7.29% of lipozyme load (based on the weight of substrate). Under these conditions, the produced CBE contained 28.65±2.00% of POP, 19.52±0.96% of POS, 3.57±0.11% of SOS and 4.81±0.47% of DAG. The addition of canola oil improved the nutritional value of CBEs which was marked by the higher percentage of linoleic acid (omega- 6, 7.98±0.92%) and linolenic acid (omega-3, 2.47±0.47%) in CBE than commercially available CBE (omega-6, 2.63±1.01%) and CB (omega-6, 2.68±0.34%). Enzymatic interesterification has not altered fatty acid content in the CBE, especially linoleic acid (omega-6) and linolenic acid (omega-3) which was characterised by no significant difference (p > 0.05) between the fatty acid profile of initial mixture and CBE. Slip melting point (SMP) value of CBE (46.25 °C) was significantly higher (p < 0.05) than the SMP value of CB (32-35 °C). In addition, the solid fat content (SFC) value of CBE was different from CB. It was due to the high amount of POP, free fatty acid (FFA) or saturated-saturated-saturated (StStSt) type of TAGs in CBE produced and also lower amount of TAGs which has oleic acid at sn-2 position. Moreover, the produced CBE behaved as pseudoplastic flow. Although there were differences of characteristics between the produced CBE with the authentic CB, it was possible to produce a high nutritional value of CBE with a physicochemical composition that was very close to that of CB by using enzymatic interesterification.