Formulation of Functional Creams Enriched with Aloe Vera Gel, Eucalyptus Essential Oil, and Vitamin E: Mixture-Design Optimization of Antioxidant Activity and Evaluation of Consumer Acceptability

The development of multifunctional cosmetic creams requires balancing functional performance with consumer acceptability. This study aimed to develop cream formulations containing aloe vera gel, eucalyptus essential oil, and vitamin E. Their relative proportions were optimized using mixture-design methodology. Ten formulations were prepared, and antioxidant activity was evaluated using the DPPH radical scavenging assay. A special cubic mixture model was fitted to the experimental data, followed by numerical optimization. The formulations were further characterized in terms of pH, microstructure, sensory attributes, and microbiological quality during refrigerated storage. Antioxidant activity varied among creams, with significant aloe vera × eucalyptus essential oil and aloe vera × vitamin E interactions. The model showed high explanatory capacity (R2 = 93.14%) and predicted an optimum mixture of 30.3% aloe vera gel, 29.3% eucalyptus essential oil, and 40.4% vitamin E. The pH of the creams remained within 4.74–5.18, while most sensory attributes were comparable among formulations. Odor and cooling sensation were formulation-dependent, while willingness to use exceeded 60% for several formulations and reached approximately 71% for BIO8. Microbial counts remained below the applicable quantitative acceptance criterion during the 60-day refrigerated storage assessment, while the specified target microorganisms were not detected under the microbiological methods employed. The findings support further investigation of ternary formulations under formulation and stability conditions relevant to cosmetic use.