Valorization of apple pomace by obtaining some bioactive ingredients with antioxidant, antimicrobial and prebiotic activities

Apple pomace (AP) is an underutilized by-product from the apple industry that has a high processing potential to obtain biobased products that meet the needs of the society, in the circular bioeconomy system. This study highlights the superior valorization of AP through microwave extraction of bioactive compounds and subsequent incorporation of apple pomace extract (APE) into the MCM-41 mesoporous silica matrix to prevent APE degradation, with the aim of being used as a bioactive ingredient for the development of new functional food products.The bioactive characterization of the APE was performed by UV-Vis, UHPLC-MS/MS and UHPLC-DAD investigations, while the loading of the APE into MCM-41-type silica matrix was confirmed by FTIR, UV-Vis, SEM and TGA-DSC investigations. The biological activity of the obtained ingredient was determined by evaluating the antimicrobial activity, prebiotic effect and in vitro biocompatibility. The obtained APE contained high total polyphenolic (136.00 mg GAE/g) and flavonoids (34.00 mg QE/g) contents and had a good antioxidant activity (1800.00 µmol Trolox/g). UHPLC-MS/MS characterization of the APE indicated important amounts of antioxidant bioactive compounds such as t-cinnamic acid (23.51 mg/g) quercetin (22.86 mg/g) and myricetin (97.24 mg/g), but also the presence of other specific bioactive compounds such as flavonoids and the glycosylated forms of flavonoids, chalchones and stilbenes. The apple polyphenolic extract was successfully loaded into MCM-41 and the resulted bioactive ingredient demonstrate antimicrobial activity against pathogenic strains, especially on the S. flexneri strain (0.625 mg/mL), a microorganism involved in dysentery, but also prebiotic effect, especially on the L. paracasei strain at noncytotoxic concentrations on L929 murine fibroblasts cell line (lower than 1.2 mg/mL). These results support further potential utilization of MCM-41 silica matrix loaded with polyphenolic extract for developing new food preparation and functional health products.