Utilization of gelatin-tragacanthin complexes for fabrication of oleogels using foam-template method: A study on the effect of CaCl2 addition.

Although oleogels are innovative fat replacers to reduce usage of saturated and trans fatty acids, susceptibility to heat treatment is a major challenge in their application. Therefore, the main aim of this study was to fabricate heat-resistant oleogel using gelatin-tragacanthin-Ca²⁺ complexes via foam-template method. For this purpose, gelatin-tragacanthin complexes (3 % w/w, at the rations of 1:1, 3:1 and 5:1) were aerated, freeze-dried, mixed with oil, and sheared in the absence and presence of Ca²⁺ (50 mM). Properties of the resulting foam (formed by aerating the complexes), the cryogels (produced by freeze-drying the foam) and oleogels were evaluated. Our results indicate that raising the gelatin-tragacanthin ratio from 1:1 to 5:1 decreased size of foam bubbles and increased their uniformity. According to scanning electron microscopy, Ca²⁺-containing cryogel exhibited dense and porous network with small-sized holes. Although tragacanthin and Ca²⁺ addition diminished oil adsorbing capacity of cryogel, they significantly enhanced oil holding capacity of oleogel to 98.89 %. The fabricated oleogels exhibited a firm gel behavior, and Ca²⁺ addition increased apparent viscosity and heat stability (80 °C, 30 min). Consequently, the findings provided new insights into preparation of heat stable oleogel, as fat mimic and texture modifier, using foam-template method.