The inhibitory effect of different chemical food preservatives on the growth of selected food borne pathogenic bacteria

The inhibitory effect of different chemical food preservatives (potassium metabisulphite, sodium benzoate, citric acid, ascorbic acid and potassium sorbate) on the growth of selected food borne pathogenic bacteria (Staphylococcus aureus, Klebsiella aerogenes, Proteus mirabilis, Pseudomonas aeruginosa and Escherichia coli) were investigated using agar diffusion technique. The concentrations used on test bacteria ranged from 0.125 - 1.5 mg/ml. The minimum inhibitory concentrations (MIC) of the five preservatives were 0.5, 1.5, 1.5, 1.5 and 1.5 mg/ml for potassium metabisulphite, sodium benzoate, citric acid, ascorbic acid and potassium sorbate, respectively. The zone of inhibition of the test bacteria ranged from 4.0 - 21 mm. S. aureus was susceptible to all the five chemical food preservatives. All the MIC of chemical food preservatives used against selected pathogenic bacteria was below the acceptable daily intake (ADI) mg/kg body weight/day. The MIC of citric acid ascorbic acid has no ADI limit in the body.   Key words: Chemical preservatives, pathogenic bacteria, minimum inhibitory concentration, acceptable daily intake (ADI), inhibition zone.