DEVELOPMENT OF MIXED OLEOGELS: EXPLORING INTERACTIONS BETWEEN LECITHINS AND MONOSTEARATE-BASED SURFACTANTS

Oleogels have been explored as fat substitutes due to their promising technological features (gel-like) and healthier fatty acid composition compared to trans and saturated fats. The aim of this study was to investigate lecithin (L)-surfactant interactions in the formation of multicomponent oleogels. Lecithins (20 or 90 wt.% of phosphatidylcholine) combined with glycerol monostearate (GMS), sorbitan monostearate (SMS) or sucrose monostearate (SAC) were evaluated as oleogelators in sunflower oil. These surfactants were chosen because they have the same nonpolar carbon chain (C18:0), but differ in the attached hydrophilic head moieties. The systems were characterized by i) rheological measurements using a stress-controlled rheometer (Anton Paar, Austria); ii) microstructure by polarized light microscope (Olympus, USA) and iii) oil binding capacity assessed by accelerated stability tests. The mechanical properties, microstructure and physical stability of the oleogels were affected by both the chemical composition of lecithins and the ratio between lecithins and surfactants. In L-GMS systems, lecithin hindered the self-assembly of the GMS, compromising the mechanical properties (G´= 191.0 ± 21.2kPa for 100-GMS and G´= 36.0 ± 1.1 kPa for L90-30:70-GMS) and reducing physical stability (~15% of oil released). Lecithin combined with SMS acted as a crystal habit modifier of monostearate crystals, forming a more homogeneous network and producing stronger oleogels (G´= 1.7 ± 0.2kPa and G´= 39.7 ± 3.4 kPa for 100-SMS and L20-10:90-SMS, respectively) with high oil binding capacity of ~65% to ~94%. However, above a threshold concentration, lecithin prevented SMS self-assembly, producing a weaker gel. A positive interaction was found in L-SAC formulations in specific ratios, since SAC cannot act as a single oleogelator. Therefore, these results provide information on the impact of solubility balance played by the combination of lecithin and fatty acid-derived surfactants combination, contributing to a rational perspective on the development and modulation of the properties of edible oleogels.