Physicochemical characterization of a sustainable postbiotic extract for skin application

The skin carries out functions such as protection and thermoregulation, but it gradually loses its physiological capacity. The use of cosmetic products has been a good solution to maintain skin’s health, and postbiotics have emerged as very promising cosmetic ingredients. Postbiotics are defined as a “preparation of inanimate microorganisms and/or their components that confers a health benefit on the host”. These comprise several metabolites, and have important biological properties (e.g., antioxidant, anti-inflammatory), thus their cosmetic application should be considered [1]. In this work, sugarcane straw was used as substrate for the production of postbiotics. A saccharification process was carried out with cellulase at 55 ºC for 24 h. Fermentation was performed sequentially after saccharification at 30 ºC, for 72 h, using Saccharomyces cerevisiae. After further processing, the cells-free extract was characterized regarding its composition (sugars, organic acids, total phenolic content, individual polyphenols), and antioxidant activity (ABTS, DPPH, ORAC). The extract had in its composition a sugar alcohol (sorbitol), and four organic acids (acetate, citrate, azelaic acid, and sebacic acid). In addition, the extract had a total phenolic content of 13.460 mg.g-1 dry extract, and polyphenols from three main groups were identified, including hydroxybenzoic acids, hydroxycinnamic acids, and flavones. Moreover, it showed antioxidant activity, with ABTS IC50 of 1.88 mg.mL-1. This work allowed the successful production of a postbiotic extract, using a by-product of sugar industry as a carbon and polyphenols source, exhibiting potential for cosmetic applications.