Chemical profile and antioxidant potency of Citrus aurantium L. flower extracts with antibacterial effect against foodborne pathogens in rice pudding

Abstract

This study was carried out to determine phytochemical composition, in-vitro antioxidant and antibacterial activities of different solvent extracts of Cyprus Citrus aurantium L. flowers, which are commonly used as flavouring agents in desserts. Essential phytochemicals such as polyphenols, flavonoids, alkaloids, and terpenes were detected in water, methanol, ethyl acetate, and hexane solvent extracts by GC/MS. The total phenolic (87.96 mg GAE/g) and flavonoid (28.20 mg QE/g) contents were found to be significantly higher (p ≤ 0.05) in the methanol extracts with higher antioxidant activities with a significant correlation (r = 0.90). The methanol extract showed the highest antimicrobial activity against Escherichia coli O157:H7, Salmonella Typhimurium, Listeria monocytogenes, and Bacillus cereus, with Staphylococcus aureus being the most sensitive one. Based on the MIC values, distinct concentrations of methanol extract were individually evaluated for their antimicrobial effect against natural flora and inoculated test pathogens in rice pudding for seven days at 8 °C. The application of methanol extract decreased the growth rate of all tested pathogens and natural flora in rice pudding. Results suggest the possibility of the application of methanol extract of Citrus aurantium flower as natural preservatives and for the isolation of bioactive agents for further use in the food and medicine industries.