Characterization of hydrogenated fats for margarine manufacturing purposes

Eight samples of hydrogenated vegetable fats were characterized by their fatty acid composition, trans isomers content and thermal behaviour, using gas chromatography (GC), infrared spectroscopy (IR), pulsed Nuclear Magnetic Resonance (pNMR) and Differential Scanning Calorimetry (DSC) techniques, respectively. Fatty acid composition showed some variations in relation to the unsaturated fatty acids. Trans isomer content, values varied from 22.8% to 35.6%. Solid fat content values were measured using AOCS and IUPAC methods, which differ in the tempering procedures. Values obtained by IUPAC method were higher than the AOCS ones, only at lower temperatures (10 and 21,1 degrees C). Samples were divided into three groups according to their solids profile: superior (C/E/G/H) intermediate (F) and inferior (A/B/D). Melting and crystallization curves were obtained by Differential Scanning Calorimetry. Melting enthalpies ranged from 51.3 to 76.5 J.g(-1) and crystallization enthalpies varied from -34.2 to -18.9 J.g(-1) Characteristic temperatures showed little differences between the samples and each of them showed a characteristic DSC curve. All samples showed a great melting range as expected for hydrogenated fats used for margarines manufacture.