Chemical composition and antimicrobial effects of essential oils of Eucalyptus globulus, Myrtus communis and Satureja hortensis against Escherichia coli O157:H7 and Staphylococcus aureus in minced beef

Food Sci Technol Int. 2011 Dec;17(6):505-15. doi: 10.1177/1082013211398803. Epub 2011 Nov 2.

Abstract

Essential oils (EOs) extracted by hydrodistillation from leaf parts of Algerian Eucalyptus globulus, Myrtus communis and Satureja hortensis were analyzed by gas chromatography/mass spectrometry (GC/MS). The main components of EOs obtained were γ-terpinene (94.48%), 1,8-cineole (46.98%) and carvacrol (46.10%), respectively, for E. globulus, M. communis and S. hortensis. The in vitro antimicrobial activity of the EOs was evaluated against Staphylococcus aureus CECT 4459 and Escherichia coli O157:H7 CECT 4267 using the agar diffusion technique. Results revealed that E. globulus and S. hortensis EOs had more antibacterial effects than that from M. communis. Minimal inhibitory concentrations (MIC) showed a range of 0.05-0.22% (volume by volume [v/v]). Sensitivity of gram-positive S. aureus was much higher than that of gram-negative E. coli. Plant EOs were added to minced beef (two-fold MIC value) at 0.10-0.44%, experimentally inoculated with the same pathogens at a level of 5 × 10(5) colony forming units (cfu)/g and stored at 5 ± 2 °C. Results showed that the EOs of E. globulus and S. hortensis had remarkable antibacterial properties, higher than that of M. communis, against S. aureus and E. coli. Indeed, a reduction of 5.8 log cfu/g (70.74% of reduction) was recorded after 7 days of storage for S. hortensis against E. coli. However, regarding S. aureus, both S. hortensis and E. globulus caused a highly significant (p < 0.05) decrease of microbial counts, most evident after 5 days of storage; S. aureus numbers were 3.50 and 2.50 cfu/g, respectively, corresponding to a reduction of 2.20 and 3.20 log cfu/g (38.60 and 56.14% of reduction) after 1 week of storage. Sensory evaluation revealed that the aroma of minced beef meat treated with EOs was acceptable by panelists at the levels used.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algeria
  • Animals
  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / pharmacology
  • Cattle
  • Cyclohexane Monoterpenes
  • Cyclohexanols / analysis
  • Cyclohexanols / pharmacology
  • Cymenes
  • Escherichia coli O157 / drug effects*
  • Eucalyptol
  • Eucalyptus / chemistry*
  • Food Handling
  • Food Preservatives / chemistry
  • Food Preservatives / pharmacology
  • Humans
  • Hydrogen-Ion Concentration
  • Meat / analysis
  • Meat / microbiology*
  • Medicine, African Traditional
  • Microbial Sensitivity Tests
  • Monoterpenes / analysis
  • Monoterpenes / pharmacology
  • Myrtus / chemistry*
  • Odorants
  • Oils, Volatile / chemistry
  • Oils, Volatile / pharmacology*
  • Plant Leaves / chemistry
  • Satureja / chemistry*
  • Staphylococcus aureus / drug effects*

Substances

  • Anti-Bacterial Agents
  • Cyclohexane Monoterpenes
  • Cyclohexanols
  • Cymenes
  • Food Preservatives
  • Monoterpenes
  • Oils, Volatile
  • gamma-terpinene
  • carvacrol
  • Eucalyptol