Tailoring starch particle morphology through enzymatic, precipitation and spray-drying techniques as sustainable microplastic alternatives in cosmetics

Microplastics have long been employed in cosmetic formulations to enhance sensory properties. However, growing environmental concerns necessitate sustainable alternatives as stated in the Regulation (EU) 2023/2055. Starch, an abundant and biodegradable polysaccharide, represents a promising candidate, yet its native form exhibits poor tactile aesthetics, limiting its application in high-end cosmetic products. Starches are powders widely used in cosmetics as humectants, absorbents, skin protectants, and viscosity adjusters. However, their irregular shape and "gritty" sensory perception have limited their use in formulations, leading to the widespread use of microplastics such as Nylon, PP, and PMMA for decades. This study investigates strategies to modify starch morphology and improve its sensory attributes for cosmetic use. Corn, tapioca, and mung bean starches were processed through enzymatic hydrolysis, freeze-drying, microprecipitation, and spray-drying to generate four distinct particle architectures: deflated spheres, sheets, smooth microparticles, and donut-like structures. Characterization was performed using scanning electron microscopy and angle-of-repose measurements. Results indicate that these modifications enhanced tactile smoothness and aesthetic performance, positioning these biopolymer matrices as promising sustainable alternatives to replace synthetic microbeads in cosmetic formulations. These reproducible and scalable protocols demonstrate that morphologically modified starch-based powders can serve as effective, eco-friendly substitutes for microplastics, aligning with sustainability goals without compromising quality.