Berries Pomace Valorization: From Waste to Potent Antioxidants and Emerging Skin Prebiotics

Fruit pomaces are agro-industrial by-products obtained in large quantities by the juice production industry, hence their reutilization is a suitable way to minimize environmental impact by transforming them into different value-added products. Considering the wide abundance and bioactive potential of berries pomaces, raspberry, strawberry, blackcurrant, and chokeberry pomace were chosen to examine and compare polyphenol content, antioxidant activity, and skin prebiotic capacity of their extracts. Extracts of 5.28 to 13.39 mg GAE ⋅ g−1 DM total polyphenol content were obtained, with significant differences in polyphenol abundance between classes. Relative antioxidant capacity index and global antioxidant score revealed that the blackcurrant pomace extract exhibited the highest antioxidant capacity. Staphylococcus epidermidis growth was promoted by lower extract concentrations, while higher concentrations showed inhibitory effects. On the other hand, Staphylococcus aureus was inhibited more strongly and no stimulation was detected in the tested concentration range (.025–.1 mg GAE ⋅ mL−1). In co-cultured experiments, a S. aureus/S. epidermidis rebalancing effect was proven for all tested extracts, whereas the best prebiotic capacity of 2.84 was achieved at .05 mg GAE⋅ mL−1 of raspberry pomace extract. In conclusion, berry pomace extracts could be valorized by extraction of their phytochemicals which are potent antioxidants and emerging prebiotics for topical application.