Pomegranate (Punica granatum L.) Peel Extracts as Antimicrobial and Antioxidant Additives Used in Alfalfa Sprouts

Aqueous and ethanolic pomegranate peel extracts (PPE) were studied as a source of phenolic compounds with antimicrobial, anti-quorum sensing, and antioxidant properties. The aqueous extract showed higher total phenolic and flavonoid content (153.43 mg GAE/g and 45.74, respectively) and antioxidant capacity (DPPH radical inhibition: 86.12%, ABTS radical scavenging capacity: 958.21 mg TE/dw) compared to the ethanolic extract. The main phenolic compounds identified by UPLC-DAD were chlorogenic and gallic acids. The aqueous PPE extract showed antimicrobial activity against Listeria monocytogenes, Salmonella Typhimurium, Candida tropicalis (MICs 19-30 mg/mL), and anti-quorum sensing activity expressed as inhibition of Chromobacterium violaceum violacein production (%). The aqueous PPE extracts at 25 mg/mL applied on alfalfa sprouts reduced psychrophilic bacteria (1.12 Log CFU/100 g) and total coliforms (1.23 Log CFU/100 g) and increased the antioxidant capacity of the treated sprouts (55.13 mu mol TE/100 g (DPPH) and 126.56 mu mol TE/100 g (ABTS)) compared to untreated alfalfa. This study emphasizes PPE's antioxidant and antimicrobial activities in alfalfa sprouts preservation.

Automated summary

Aqueous pomegranate peel extract (PPE) shows higher total phenolic and flavonoid content, better antioxidant capacity, and exhibits antimicrobial and anti-quorum sensing activity. The main phenolic compounds identified are chlorogenic and gallic acids. Treatment of alfalfa sprouts with aqueous PPE reduces bacterial counts and enhances antioxidant capacity.