Enhancing Oil Binding Capacity in a Palm-Kernel Based Fat: Impact of Processing Conditions and Physical Properties

The ability of a fat crystal network to entrap liquid oil is known as oil binding capacity (OBC) and is an imperative property in semi-solid fats for use in confectionery, bakery, and snack products. Understanding the factors that increase the OBC of fats is crucial for developing fat-based foods more resistant to unwanted oil migration.

In this study, a palm-kernel-based fat (PKO) was diluted and crystallized under different processing conditions to generate a wide range of physical properties and OBC. Three dilutions were created by combining PKO with soybean oil (SBO) – 75% PKO (containing 25% SBO), 50% PKO (50% SBO), and 20% PKO (80% SBO) and were crystallized at 33 °C, 30 °C, and 22 °C; respectively. The samples were crystallized using fast (FCR; 4.6 °C/min) and slow (SCR; 0.1 °C/min) cooling rates as well as with (w) and without (wo) high-intensity ultrasound (HIU; 20 kHz) resulting in four processing conditions – FCR wo HIU, FCR w HIU, SCR wo HIU, SCR w HIU. After crystallization, the following properties were measured – solid fat content (SFC), viscoelasticity (G´, G´´, δ), hardness, crystal microstructure, melting behavior (Tpeak, enthalpy), and OBC using a centrifuge (OBCc). Samples were stored at 22 °C and d 5 °C for 48 h and the aforementioned properties were measured again with one additional measurement – OBC using a filter paper (OBCp).

Results show both methods used to measure OBC were significantly correlated with SFC (rs=0.912, p< 0.001) (rs=0.777, p< 0.001), hardness (rs=0.883, p<0.001) (rs=0.812, p< 0.001), storage modulus (rs=0.674, p< 0.001) (rs=0.526, p=0.017), enthalpy (rs=0.842, p< 0.001) (rs=0.812, p<0.001), and the number of crystals (rs=0.655, p<0.001) (rs=0.728, p<0.001) for the OBCc and OBCp; respectively. Indicating OBC can be increased in a palm-kernel-based fat by formulating hard, elastic fats with high SFC, high enthalpy, and many crystals.