Thermoreversible oleogelation of fatty acid monoglyceride-containing sunflower oil from a rheological approach

Nowadays, there is a growing concern among consumers about the impact of diet on health. In this regard, oleogelation has been proposed as a promising strategy to replace unhealthy fats, as well as to encapsulate water-insoluble bioactive compounds in food matrices. Consequently, the development of thermoreversible oleogels may play an important role in the bioavailability and biostability of functional foods and the beneficial effects associated with them. The aim of this work was to evaluate the viscoelastic behavior of oleogels using a commercial food additive (E471) composed of fatty acid monoglycerides (MG). Furthermore, the study of sol-gel transitions of these thermoreversible oleogels allowed to obtain the optimum concentration of gelling agent required. Refined sunflower oil containing 2-5 wt.% of E471 were characterized by means of SAOS tests, as a function of temperature. All these systems were liquids above 48°C, forming stable oleogels below 20°C. An improvement of the elastic component of them was observed as gelling agent concentration was higher. Oleogels containing 4 and 5 wt.% MG showed very similar viscoelastic properties and high stability at body temperature (ca. 37°C). Conversely, systems containing 2% or 3% led to the formation of weaker gels exhibiting thermo-reversibility but only the latter was stable at body temperature. Therefore, sunflower oleogels containing MG above 3 wt.% could be regarded as potential carrier food matrices for lipid-soluble active ingredients. To this end, the modulation of the oleogel network consistency should play a key role in maintaining the integrity of the active principle during gastrointestinal transit.