Studies on the efficacy of some preservatives used in packaged orange drinks

Abstract

The antibacterial activity of benzoic acid and sodium benzoate was investigated against bacterial isolates from packaged orange drinks using agar well diffusion and broth dilution methods. The antibacterial activity of
the test agents against the standard NCTC bacteria species was also tested. The bacterial count from the packaged orange drinks ranged from 3.0 x 105 cfu/ml and 1.43 x106 cfu/ml. The bacteria species detected
consisted of Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and Micrococcus sp. The zones of inhibition of benzoic acid ranged from 19.0 mm – 31.5 mm while that of sodium benzoate ranged from 13.5
mm – 36.5 mm. The Minimum Inhibitory Concentration (MIC) of the preservatives against the test bacteria ranged between 0.156 ìg/ml and 0.625 ìg/ml while the Minimum Bactericidal Concentration (MBC) ranged
between 0.313 ìg/ml and 500 ìg/ml. The preservatives were more effective against the Gram positive bacteria than the Gram negative bacteria. The preservatives at the concentration used in the examined drinks are
inadequate to keep off indicator organisms and to ensure their safe consumption.