The Impact of Starches from Various Botanical Origins on the Functional and Mechanical Properties of Anhydrous Lotion Body Bars

Starch, as a natural, low-cost, and vegan-friendly raw material, aligns well with the growing demand for sustainable, zero-waste, and waterless cosmetic products. Its biodegradability and natural origin allow for minimal environmental impact during production and disposal. Anhydrous lotion body bars, solid and water-free alternatives to traditional moisturizers, offer high concentrations of active ingredients that are more effective and have a longer shelf life. Their solid form enables packaging in paper-based containers, reducing plastic waste. To address formulation challenges such as excessive greasiness, poor absorption, or lack of structural stability, which are often associated with the high oil content of anhydrous body lotion bars, starch may serve as a promising natural additive. The aim of this study was to optimize the formulation of an innovative starch-based anhydrous lotion bar. For this purpose, physicochemical analyses of starches from various botanical sources (corn, rice, tapioca, waxy corn and potato) were performed, along with evaluations of the functional (including commercially acceptable form, hardness sufficient for application, product stability, reduced greasiness and stickiness) and mechanical properties of the resulting bars. Additionally, the rheological behavior was described using the De Kee model. The results indicate that a 2.5% starch addition, regardless of its botanical origin, provides the best balance between viscosity and ease of application. Moreover, starches with a low moisture content and high oil absorption capacity effectively reduce the greasy skin sensation. These findings demonstrate the potential of starch as a natural multifunctional additive in the development of stable, user-friendly anhydrous lotion body bars.