Olive Leaves and Citrus Peels: From Waste to Potential Resource for Cosmetic Products

Abstract

Resource depletion and food waste accumulation represent a tremendous socio-economic and environmental problem. One promising strategy involves the use of byproducts derived from food waste as ingredients for cosmetic products. The aim of this work is to propose clementine peels and olive leaf extracts as value-added bioproducts for a cosmetic cream. Extracts were obtained by super critical extraction showing an antioxidant activity of ca. 25%. No cytotoxic effects of the extracts were recorded on keratinocyte cells up to a concentration of 4% v/v ratio within 24 h. The incorporation of clementine peels and olive leaf extracts into creams did not compromise their stability, as demonstrated by Turbiscan analyses at room and extreme (40 °C) storage conditions. The safety profiles of the final cosmetic formulations were further in vivo demonstrated on human volunteers. We analyzed the trans-epidermal water loss and variation of the skin’s erythematous index, which showed profiles that almost overlapped with the negative control. Moreover, rheological analysis of the resulting creams evidences their suitable spreadability with similar pseudoplastic profiles, although a slight reduction of viscosity was recorded by improving the extracts’ concentrations. The proposed approach highlights the advantage of combining byproduct resources and supercritical fluid extraction to obtain a safe and eco-friendly face cream.