Determination of minimum inhibitory concentration (MIC) of sodium diacetate on spoilage microorganisms in carbonated beverages by culture media

Sodium diacetate is a safe chemical presevative which is used as an inhibitor against mould، yeast and some bacteria. In this study anti-microbial effect of sodium diacetate on preventing the growth of some spoilage microorganisms in carbonated beverages was investigated by broth diulation suceptibility test in medium. At the concentrations of 101، 102، 103 and 105 cells of Saccharomycess cerevisiae per ml 156، 313، 1250 and 5000 ppm of sodium diacetate were respectively determined as the minimum inhibitory concentrations (MIC) preventing growth of the yeast. As for Candida krusei، 625، 1250، 2500 and 5000 ppm of sodium diacetate were MIC inhibiting the growth of the yeast at concentrations of respectively 101، 102، 103 and 105 cells/ml. 2500 and 5000 ppm of sodium diacetate were determined as MIC inhibiting the growth of Leuconostac mesenteroides at the concentrations of respectively 102، 104 bacteria/ml، and for 102 bacteria/ml of Lactobacillus delbrukii was prevented by adding 2500 ppm sodium diacetate. No inhibitory effects of different concentrations of sodium diacetate observed at none of the prepared spore suspension of Aspergilus niger، so no concentrations of sodium diacetate were determined as MIC for this species of mould. The results show that sodium diacetate has inhibitory effects on the above selected yeast and bacteria but no inhibitory effects on the mould of Aspergilus niger.