One-step preparation of emulsion gels stabilized by carboxymethyl chitosan and cinnamaldehyde

Emulsion gels are typically prepared via a two-step process involving emulsification followed by gelation. However, this approach is complex, as emulsion droplets may aggregate before gelation, and harsh gelation conditions may disrupt the emulsion structure and degrade encapsulated bioactive components. Recently, one-step methods have emerged, particularly under high oil content or by inducing a transition from emulsion to gel. In this study, we propose a facile one-step method to prepare uniform and stable low-oil emulsion gels. A carboxymethyl chitosan (CMC) solution and an oil phase containing cinnamon essential oil (CEO) were homogenized using a high-speed disperser at 10,000 rpm for 2 min under 23 °C, inducing a transition from solution to gel. Schiff base reactions between the amino groups of CMC and the aldehyde groups of cinnamaldehyde occurred simultaneously at the oil-water interface and in the aqueous phase, enabling concurrent emulsification and gelation. Increasing CMC concentration (1–2 wt%) and CEO content significantly reduced droplet size, accelerated gelation, and improved structural uniformity. Confocal laser scanning microscopy (CLSM) and cryo-scanning electron microscopy (cryo-SEM) analyses revealed that higher CMC concentrations promote denser gel networks, while increased CEO concentrations yield smaller and more uniformly dispersed oil droplets. Stability assessments demonstrated that emulsion gels prepared with 2 wt% CMC exhibited superior storage stability, freeze-thaw resistance, and centrifugal stability. This facile one-step method for preparing low-oil emulsion gels holds promise for applications in low-fat substitutions development and the encapsulation of sensitive bioactive compounds.