CRYSTALLIZATION, MICROSTRUCTURE AND POLYMORPHIC PROPERTIES OF SOYBEAN OIL ORGANOGELS

Harmful effects of high consumption of saturated and trans fatty acids motivated the research on structuring agents capable to immobilize liquid oils, rich in polyunsaturated fatty acids, an organized tridimensional network named organogels or oleogels. The aim of this work was to evaluate the crystallization, microstructure and polymorphism properties of soybean oil (SO) organogels structured with 6% (w:w) of structuring agents - candelilla wax (CW), sorbitan monostearate (SMS) and fully hydrogenated palm oil (FHPO) using a simplex centroid experimental design added singly, in binary or ternary association. The thermal behavior, crystallization kinetics, physical stability by temperature cyclization, microstructure and polymorphism were evaluated for organogels. CW promotes the formation of dense crystalline networks increasing solid content (5.08%) and melting point (45.51°C) besides decreasing the crystallization induction time, FHPO improved the solid content (5.54%) with the lower melting point (-34.43°C), initial crystallization temperature (21.99°C) and organogel formation only at the cooling temperature (5°C). The SMS concentration (until 6%) was insufficient to form organogels delayed onset of crystallization when combined with FHPO. The binary interaction of FHPO+CW increased the organogel thermal resistance and physical stability compared to the FHPO used as the sole structuring agent. The interactions between SMS+CW and SMS+CW+FHPO accelerated the crystallization process. The cyclization tests (cyclization 1: 5°C/48h+35°C/24h+5°C/24h; cyclization 2: 35°C/48h + 5°C/72h) showed that all the systems resulted in firm organogels, except for SMS or FHPO singly. The polymorphism analysis showed β’ form to all stable organogels. The CW was indispensable to form stable organogels; while the SMS can improve the organogel thermal characteristics when associated with FHPO that contribute mainly for increasing the solids content and form organogels at lower temperature. So, this combination of structuring agents, mainly CW+FHPO, allow to reduce formulation costs to obtain stable organogels using safe and commercially available raw materials.