Search results

A total of 12 Alliums, used for culinary purposes, were examined for anti‐bacterial activity against Escherichia coli using disc assay and minimum lethal concentration methods. The 12 Alliums were: garlic (Allium sativum); onion (A. cepa); shallot (A. cepa var. ascolonicum); everlasting onion (A.cepa “Perutile”); ramsons (A.ursinum); leek (A. porrum); chives (A. schoenoprasum); wild leek (A. ampeloprasum); Babington’s leek (A. ampeloprasum var. babingtonii); Chinese chives (A. ramosum); nodding onion (A. cernuum) and crow garlic (A. vineale). Garlic, ramsons, wild leek, Babington’s leek, Chinese chive and crow garlic exhibited anti‐bacterial activity. The correlation coefficient between the results of the disc assay and minimum lethal concentration methods was highly significant (r = 0.977; p = 0.0001).

A quantitative method involving colony counting was undertaken to assess the antibiotic effects of garlic Allium sativum on possible food‐borne bacteria. The investigation using garlic was targeted at higher education students planning an Independent Study or Dissertation into the antibacterial properties of food plants. The effect of concentrations of garlic varying from 0 per cent to 20 per cent in chicken stock, which had been inoculated with either E.coli B and S. albus, was investigated over three days. Bacterial numbers were reduced with increased garlic concentration and with the duration of incubation. Heating the garlic for 30 min at 100 C destroyed its anti‐bacterial activity.

This paper is aimed at food science or biology students planning a practical independent study into the antimicrobial properties of spices and academic staff wishing to develop a straightforward and reproducible practical activity.

Disc‐diffusion assays are used to investigate the antimicrobial activity of cinnamon and cloves against two bacteria Escherichia coli B and staphylococcus albus and a yeast Saccharomyces cerevisiae. Aqueous and alcoholic extracts of the spices and alcoholic extracts of their essential oils are examined. Minimum inhibitory concentrations of alcoholic extracts of both spices and oils are also determined.

Both spices demonstrated microbial inhibitory effects; alcoholic extracts had greater activity than aqueous extracts. Additionally, essential oils had greater activity than the spices. Minimum inhibitory concentrations were smaller with the oils than with the spices.

Although the research for this paper involved just two spices, such is the size of the plant kingdom that there are wide opportunities for further investigations using this procedure.

Disc‐assays were found to be a simple, cheap and reproducible practical method. For this paper, micro‐organisms available for educational purposes were used; however, other organisms could be investigated depending upon available microbiological expertise and facilities.

The results demonstrate that the antimicrobial effects of spices and particularly their essential oils can be examined using disc‐diffusion assay. The method provides many opportunities for student investigation.