Sustainable Cosmetics: Valorisation of Kiwi (Actinidia deliciosa) By-Products by Their Incorporation into a Moisturising Cream

The growing population has intensified food processing, increasing the generation of agro-industrial waste. This waste is rich in bioactive compounds; therefore, it can be valorised by extracting their compounds of biological interest and incorporating them into cosmetic products. In this work, an extract was obtained from kiwi peels and characterised regarding its biological properties and phenolic composition. Results demonstrated that the extract presented antioxidant activity against DPPH and ABTS radicals (IC50 values of 244 mg/L and 58 mg/L, respectively) and antibacterial activity against Staphylococcus aureus. Catechin and epicatechin (flavonoids), as well as chlorogenic acid (phenolic acid), were the main phenolic compounds identified. Subsequently, the kiwi peel extract was incorporated into cosmetic formulations and their antioxidant properties and stability were evaluated. An increase in the antioxidant activity of the moisturising cream was observed upon the extract’s addition. Also, no microorganisms were present in any formulation prepared, attesting to their microbial safety. Finally, the results from the stability analysis revealed that the moisturising creams remained relatively stable for two weeks. These findings suggest that extracts from kiwi peels have the potential to be used as natural additives to produce value-added cosmetic products in a more sustainable manner.