Description of melting curves of enzymatically interesterified blends of fully hydrogenated palm olein and soybean oil by sigmoidal functions

Margarines and shortenings are generally characterized by their solid fat content (SFC) and melting point. Interesterification has been widely used for production of trans-free margarines and shortenings. In this study, blends of fully hydrogenated palm olein (FHPO) and soybean oil were interesterified using the Lipozyme TL IM and the potential of three sigmoidal functions (including the Logistic, Sigmoid and Gompertz equations) in description of SFC or slip melting point (SMP) of the enzymatically interesterified blends was evaluated. The SFC as a function of temperature (SFCf(T)) or saturated fatty acids (SFCf(SFA)) curves, and SMP as a function of SFA (SMPf(SFA)) curve had sigmoidal shapes and all the sigmoidal functions were able to describe the SFC and SMP curves. However, the Gompertz model described them in the best way. Mean absolute error (MAE) of SFCf(T) and SFCf(SFA) models (described by the Gompertz function) were less than 1.75% and 1.22% respectively. The Gompertz function could describe the SMPf(SFA) curves with high R2 (0.99) and low MAE (0.65 °C). In addition, the obtained model could describe the SMP of interesterified palm olein-based fat blends with MAE lower than 3.1 °C. However, poor results obtained when the model was used for prediction of SMP of interesterified fats made from fully hydrogenated soybean oil (MAE=5.2-9.8 °C). Models described in this study can be used as screening tools in formulation of interesterified margarine and shortening fats.