Food-Grade Microemulsion for High-Loading Octacosanol: Formulation Optimization, Characterization, and Biological...

Octacosanol (OCT) is a natural bioactive compound with multiple physiological activities. However, its poor aqueous solubility limits its application in functional beverages, and existing delivery systems suffer from low loading and excessive emulsifier use. This study aimed to develop a food-grade OCT-loaded microemulsion (OCT-ME) with high loading capacity. The formulation was optimized via pseudo-ternary phase diagram analysis combined with particle size and polydispersity index (PDI) measurements, and the characterization and biocompatibility of the optimized OCT-ME were systematically evaluated. The optimal formulation (w/w) consisted of 2.4% corn oil, 16.2% mixed emulsifiers (Tween 80/Span 80, HLB = 13), 5.4% 1,2-propanediol (Km = 3:1), and 75.0% deionized water, achieving a high OCT loading capacity of 1.0% (w/w). The resulting OCT-ME displayed a uniform particle size of 10.37 nm with a low PDI and exhibited excellent stability, favorable gastric OCT protection, and superior biocompatibility (cell viability > 90% at 5-25 μg/mL). This work addresses the key limitations of existing OCT delivery systems, providing theoretical support for the efficient solubilization and delivery of OCT in functional beverages.