Antibacterial activity of carrot peel HCl-ethanol extracts and its potential application in meat preservation

Abstract

Natural plant extracts have been employed extensively in food products due to their antioxidant and antimicrobial activity. Ethanolic extracts of four selected vegetable peels, (kiwi, carrot, sweet potato and eggplant) in addition to red pepper fruit were evaluated for their polyphenolic contents, showing carrot peel extract (CPE) having the highest levels of phenolics and flavonoids. CPE exhibited a strong antioxidant activity (88.81% oxidation inhibition at 500 μg/mL), via scavenging 2, 2-Diphenyl-1-picrylhydrazyl (DPPH). The five extracts showed antibacterial activities against two Gram-positive ( Staphylococcus aureus , Bacillus cereus) and two Gram-negative ( Salmonella typhi , Escherichia coli) bacteria, where CPE proved the most effective antibacterial, with a minimal inhibitory concentration of 20 μg/mL, without any bacterial resistance. Adding CPE to ciprofloxacin (CIP) (1:1) showed a combination effect. HPLC of CPE revealed its inclusion of β-carotene pigment (1.5 mg/g) and a great number of flavonoid and phenolic compounds, capable to act as antimicrobial agents. Ground meat samples supplemented with 40 and 100 μg/g of CPE reduced their total viable, coliforms and Psychrotrophs count and extended their shelf life at 4 °C to 12 days. So, CPE can be safely used as a natural preservative that can also maintain the sensory properties of stored meat product. • Five vegetable extracts were evaluated for polyphenolic contents and bioactivity. • Carrot peel extract (CPE) contained the highest levels of phenolics and flavoinds. • CPE exhibited a strong antioxidant activity via scavenging DPPH. • CPE has strong antibacterial action, (MIC = 0.2 μg/disc) against pathogenic bacteria. • CPE can extend the shelf life of minced meat preserved at 4 °C from 6 to 12 days.