Cooling rate, sorbitan and glyceryl monostearate gelators elicit different microstructural, viscoelastic and textural properties in chia seed oleogels

Abstract

Recently the structuring of liquid oils with low molecular weight organogelators has received much attention. Food products devoid of trans fats, with tailored rheological and textural properties can be designed for desired applications by properly selecting the organogelator and cooling rate used in their formation. Nevertheless, studies regarding these points are still scarce. In this work the effect of two different food-grade gelators (glyceryl monostearate, GM and sorbitan monostearate, SM) and different cooling rates (1, 3 and 9 °C/min) on the microstructural, viscoelastic and texture properties of chia seed oleogels (GMO and SMO, respectively) were evaluated. Gelator and chia seed oil (ChSO) were mixed in 1:10 mass ratio. SMO formed crystalline needle-like structures, with faster cooling rates producing smaller crystals (higher crystallinity index) and a more compact network. GMO showed an opposite crystallinity index dependence with cooling rate than SMO. GMO hardness higher than that of SMO, and increased while that of SMO decreased as cooling rate was faster. Both GMO and SMO showed a thixotropic dependence of the storage (G') and loss (G") moduli with forward-backward temperature ramp (5–80-5 °C). Both moduli values were higher for GMO than for SMO independently of cooling rate used. A thixotropic index was obtained, which reflected that GMO had a more thermo-reversible structure than SMO. The results of this study indicate that the formation mechanism of chia seed oleogels was affected by the cooling rate and the chemical nature of the gelator, and elicited completely different microstructural and mechanical responses.