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 <i>Staphylococcus aureus</i>, <i>Escherichia coli</i>, <i>Pseudomonas aeruginosa</i>, and <i>Candida albicans</i> 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.