Stability of synergistic behavior in ethyl cellulose-glycerol monostearate binary oleogels

This study investigates how synergistic interactions between ethyl cellulose (EC) and glycerol monostearate (GMS) govern the mechanical stability of binary oleogels during storage. Over 14 days at 22 °C, single-component GMS oleogels underwent a polymorphic transition from the metastable sub-α to the more stable β form, resulting in a pronounced loss of mechanical strength. In contrast, the extent of this transition in EC-GMS binary systems depended on whether the EC concentration was below, at, or above its critical gelation concentration (CGC), the threshold required to form a self-supporting polymer network. Formulations prepared with EC below its CGC (e.g., 2% EC) exhibited a significant reduction in hardness during storage, whereas those containing EC at or above its CGC maintained their synergistic enhancement in gel strength, attributable to a delayed GMS polymorphic transition. Moreover, preservation of this synergistic effect was governed by the EC/GMS ratio. When EC was used at its CGC (6%), at least 10% GMS was required to sustain gel strength over time. Increasing EC concentration also produced a greater shift in the GMS O-H stretching bands prior to storage, but was not observed after the polymorphic transition, thus demonstrating the direct contribution of hydrogen bonding to the synergistic behavior of the binary oleogels. Collectively, these findings provide a mechanistic basis for leveraging EC-GMS synergy to design physically stable oleogels with reduced total gelator concentration, thereby enabling the development of cost-effective and functional fat mimetics.