High internal phase emulsion (HIPE)-templated biopolymeric oleogels: a potential alternative for saturated fat replacement in pound cakes

Consumption of trans and saturated fats is associated with deleterious health effects, such as higher incidence of cardiovascular diseases and obesity. However, plastic fats play an important role on the structure and sensory aspects of food products, posing a challenge to remove or even reduce them in commercial formulations. Therefore, alternatives seeking the replacement of these fats in foods, especially in bakery products, have been widely investigated. Oleogels have shown to be promising ingredients to overcome these problems. Herein, we evaluated the use of biopolymeric oleogels formed by an indirect approach in the formulation of pound cakes. Oleogels were produced from the drying of high internal phase emulsions (HIPE) stabilized by covalent complexes between sodium caseinate (SC) and quercetin (Q). The complexes between the protein and the phenolic compound were produced under alkaline conditions (pH 9) in the presence of oxygen, varying the molar concentration of Q (2.5 and 25 µmol/mL) with a fixed SC amount. HIPEs stabilized with different concentrations of SC or SC:Q complexes (2 to 6% w/w) were dried in a forced circulation oven, varying the temperature between 80 and 120 °C. The visual appearance and oil binding capacity of emulsion-template oleogels were evaluated, showing that HIPE stabilized with 4% w/w of SC:Q complex, with the highest Q concentration (25 µmol/mL) and dried at 120 °C produced the oleogel with the lowest oil loss under centrifugation (~96±3 %). Therefore, the oleogels formed under these parameters were selected for further cake application. Formulations with palm oil (PO), sunflower oil (SO) and SC-oleogel were taken as controls. The different cake batters were compared for viscosity, apparent density, and microstructure. Moreover, the quality attributes of the baked cake, such as specific volume, baking loss and firmness, were analyzed the day after its production. All cake batters showed shear thinning behavior; however, there was a significant difference in apparent viscosity between the formulations. The viscosity observed at a fixed shear rate unveiled the impact of incorporating the oleogel in cakes (PO > SC:Q-oleogel > SC-oleogel > SO). The highest viscosity of the batter containing PO may be associated to the fat crystals and substantial air bubbles occurrence causing a greater resistance to flow. The microscopy images depicted a greater amount of air bubbles in the cake batters prepared with PO and SC:Q-oleogel. Interestingly, after baking, the cake produced with PO showed the lowest specific volume (~1.43 cm3/g) and, consequently, the highest firmness (1,116 gf), probably due to less stabilization of air bubbles during baking. No significant differences in firmness were observed between the other cakes. Our results point towards the potential applications of HIPE-template oleogels as a replacer for saturated fat in pound cakes.