Citrus fruit extracts with carvacrol and thymol eliminated 7-log acid-adapted Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes: A potential of effective natural antibacterial agents

Doohyun Chung, Tae Jin Cho, Min Suk Rhee

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

Despite the widespread belief that citrus fruit extracts (CFEs) are microbiologically safe due to their acidity, limited bactericidal effect results in low applicability as antibacterial agent and outbreaks occurred by acid-adapted pathogens. Here, we examined the antibacterial effects of CFEs [lime (Citrus medica), lemon (Citrus limon), calamansi (Citrus microcarpa)] combined with essential oil components (EOCs; carvacrol and thymol) against non-acid-adapted/acid-adapted Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes under 22 °C for 5 min. CFEs (<20%) alone or small amounts of EOCs (2.0 mM; 0.032%) alone could not inactivate the target bacteria effectively. However, combined treatments exhibited marked synergy: CFE + EOCs eliminated all the bacteria (>6.9 log CFU/ml). Among the CFEs tested, the highest synergism was shown by calamansi, an exotic citrus fruit previously unrecognized as an antibacterial agent. Although acid-adaptation improved bacterial survival, calamansi (<20%) + EOCs (<0.032%) completely inactivated even the most resistant pathogen (E. coli O157:H7). Validation test also showed that all tested commercial juice products also eliminated acid-adapted pathogens when used with EOCs. Physicochemical analysis of tested CFEs (pH measurement and HPLC analysis of components) revealed that low pH and flavanone (hesperidin) did not contribute to the synergistic bactericidal effects. Rather, the high citric acid content is likely to contribute to the strong synergistic effect with EOCs by damaging susceptible bacterial membranes. Sensory scores for CFEs were not altered by addition of EOCs at concentrations up to 1.5 mM. This study provides new insight into the utility of CFEs with EOCs to improve not only the microbiological safety of food products containing CFEs but also their applicability as natural antibacterial complex.

Original languageEnglish
Pages (from-to)578-588
Number of pages11
JournalFood Research International
Volume107
DOIs
Publication statusPublished - 2018 May

Bibliographical note

Funding Information:
This work was supported by Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry and Fisheries (iPET) through High Value-added Food Technology Development Program, funded by Ministry of Agriculture, Food and Rural Affairs (MAFRA) (314046-3). The authors thank School of Life Sciences and Biotechnology for BK21 PLUS Korea University and the Institute of Biomedical Science and Food Safety, CJ-Korea University Food Safety Hall, for providing the equipment and facilities.

Publisher Copyright:
© 2018 Elsevier Ltd

Keywords

  • Acid-adaptation
  • Carvacrol
  • Citrus fruit extract
  • Foodborne pathogen
  • Synergistic antibacterial effect
  • Thymol

ASJC Scopus subject areas

  • Food Science

Fingerprint

Dive into the research topics of 'Citrus fruit extracts with carvacrol and thymol eliminated 7-log acid-adapted Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes: A potential of effective natural antibacterial agents'. Together they form a unique fingerprint.

Cite this