Fuji apple (Malus domestica Borkh. cv. Red Fuji) pomace extracts as a source of antimicrobial and antioxidant polyphenols

This study aimed to assess the antibacterial and antioxidant properties of both crude polyphenol extract (CPE) and purified polyphenol extract (PPE) obtained from Fuji apple pomace. The antibacterial capacity of both extracts against Staphylococcus aureus was investigated by evaluating the inhibition zones, minimum bactericidal concentrations (MBC), growth curves and bacterial morphology of S. aureus treated with CPE or PPE, as well as the performance in simulated food systems. The antioxidant activity of CPE or PPE was assessed using the ABTS radical scavenging and ferric reducing antioxidant power (FRAP) assays. The results showed that PPE exhibited potent antibacterial activity against S. aureus, which was further confirmed by the bacterial morphology. It was revealed that PPE only exerted strong antibacterial effect in starch-based food system while CEP did not show such effect in all systems. The results of the ABTS and FRAP assays indicated that both PPE and CPE possess strong antioxidant activity, from which PPE showed much higher capacity than that of CPE. Therefore, PPE from Fuji apple pomace can be used as a novel antibacterial agent for food preservation and natural antioxidant for functional food and nutraceutical products.