Cork powder: Benefits and limitations as a sustainable cosmetic ingredient

To compensate for the massive environmental footprint of the cosmetic industry, this sector aims at a circular production/consumption system while intersecting the consumers' concerns about the exacerbated exploitation of natural resources. The high amount of agro-industrial waste generated by cork industries is of great interest due to the sustainable and regenerative capabilities of Quercus suber bark. This work aimed to explore the properties of cork powder, a by-product from cork processing, as a putative cosmetic ingredient. This powder was studied regarding the flowability and compressibility envisioning its use in solid water-free formulations, as well as the potential use as a functional ingredient in skin care and sun care formulations. Cork powder revealed a high compressibility and cake strength, which favors the formulation of water-free pressed powders. Poor flowability (Hausner ratio of 1.38 ± 0.01) should be, however, considered in the formulation design. The powder also revealed high oil absorption ability (203.6 ± 1.4 g/100 g) and sun protection factor (SPF) boosting effect, increasing SPF twofold when compared to a standard formulation. Ultimately, the safety profile of the cork powder was confirmed in cells representative of the human epidermis up to 50 mg/mL. Limitations of this product are associated with being a natural product, namely a high microbiological burden. This issue, along with stability and reproducibility should be addressed before considering industrial application. Cork powder showed a multifunctional profile, supporting its use as a sustainable stiffening ingredient agent of solid/water-free decorative cosmetics, or as a mattifying and photoprotective agent.