Effects on the Physical Properties of Corn Oil Oleogels Structured with Different Ratios of Rice Bran or Carnauba Waxes

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The new requirements imposed by the US Food and Drug Administration to ban trans fatty acids, and the pressure to reduce saturated fats in foods pose a significant challenge to developing lipid bases with compatible technological characteristics and similar sensory properties. Natural unsaturated oils do not have suitable physicochemical properties for direct use in food formulations. Thus, oleogelation appears as one of the most promising lipid modification techniques. The aim of this study was to develop a wax-based oleogel to be used as a fat replacement. The corn oil was structured with carnauba (CBW) or rice bran wax (RBW) in different ratios (2, 4, 6, and 10%). The oleogels were analyzed by oil binding capacity (OBC), texture properties, PLM (polarized light microscopy), visual test, and DSC (differential scanning calorimetry). The visual test at room temperature shows that the RBW structured very stable oleogels even in the lowest ratio (2%) for 60 days. The OBC was higher than 99% using RBW as oleogelator in all percentages after 60 days. On the other hand, only 10% of CBW provided a strong network to the corn oil. The enthalpy (DH) in the melting curves of the RBW-oleogels (4, 6, and 10%) were significantly higher (3.12±0.82, 8.42±0.43, and 15.04±1.81 J/g) compared to CBW oleogels (1.99±1.41, 3.47±1.45, and 11.00±0.40 J/g). The firmness of 2% RBW-oleogels (66.9 ± 15.7 g) was significantly higher (p< 0.05) than 2% CBW-oleogels (1.80 ± 1.14 g) and this behavior was observed in all percentages. The microstructure of wax-based oleogels consisted of platelet-like spherulites and clustered crystal-aggregates along with one-dimensional needle-like crystals. The RBW-oleogels exhibited a denser crystal network with stronger birefringence. The results show that rice bran wax is stable even in small ratios compared to carnauba wax generating an appropriate fat replacement since less was needed.