Experimental Valorization of Recycled Palm Oil in Topical Formulations: Preparation, Characterization, and Antimicrobial Assessment

Sustainable strategies for revalorizing food industry by-products are increasingly relevant in the development of modern experimental dermato-cosmetic formulations. In this study, two semisolid cosmetic creams (R10 and EM-R10) were designed using recycled palm oil—physically purified after intensive frying—as the lipid phase. The recycled oil was incorporated strictly within a controlled experimental framework and does not imply cosmetic-grade regulatory compliance. The formulations incorporated distinct bioactive profiles: R10 combined apricot and pineapple extracts with lime essential oil, while EM-R10 integrated fir bud and green tea extracts alongside the same essential oil. Both preparations contained Fragard as a preservative and niacinamide and panthenol as vitaminic components. The physicochemical properties of the formulations were assessed through rheology, confocal microscopy, ATR-FTIR, SEM, DSC, and contact angle measurements. Antimicrobial activity was evaluated against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans using disk diffusion and broth microdilution assays. The results demonstrate that, despite partial thermal degradation, recycled palm oil retains modified structural features that influence formulation-related properties relevant to topical systems. EM-R10 showed superior spreadability, adhesion, stability, and diffusion-related performance, as well as improved antimicrobial activity, within the investigated experimental conditions, highlighting recycled palm oil as a promising sustainable lipid phase for experimental dermato-cosmetic formulations, pending further purification, toxicological evaluation, and regulatory compliance assessment.