Compositional and textural properties of milkfat–soybean oil blends following enzymatic interesterification

Milkfat–soybean oil blends were enzymatically interesterified (EIE) by Aspergillus niger lipase immobilized on SiO2–PVA hybrid composite in a solvent free system. An experimental mixture design was used to study the effects of binary blends of milkfat–soybean oil (MF:SBO) at different proportions (0:100; 25:75; 33:67; 50:50; 67:33; 75:25; 100:0) on the compositional and textural properties of the EIE products, considering, as response variables, the interesterification yield (IY), consistency and hardness. Lipase-catalysed interesterification reactions increased the relative proportion of TAGs’ C46–C52 and decreased the TAGs’ C40–C42 and C54 concentrations. The highest IY was attained (10.8%) for EIE blend of MF:SBO 67:33 resulting in a more spreadable material at refrigerator temperature in comparison with butter, milkfat or non-interesterified (NIE) blend. In this case, consistency and hardness values were at least 32% lower than values measured for butter. Thus, using A. niger lipase immobilized on SiO2–PVA improves the textural properties of milkfat and has potential for development of a product incorporating unsaturated and essential fatty acids from soybean oil.