Introduction and objective: Sodium benzoate (SB) and potassium sorbate (PS) have long been used as preservatives in foods and other products. The aims of this study were to compare the inhibitory effect of different concentrations of two preservatives SB and PS on Aspergillus niger and Penicillium notatum, and to study the probability of existing and synergistic effect in combining these two preservative together.
Materials and methods: Preservative effects of separate concentrations (0.02, 0.04, 0.06, 0.08 and 0.1%) and different combinations of SB and PS (0.08 SB + 0.02 PS, 0.06 SB + 0.04 PS, 0.04 SB + 0.06 PS, 0.02 SB + 0.08 PS) on A. niger and P. notatum in yeast extract sucrose broth at preschedule days i.e. 0, 4, 10, 14, 18, 21, 24, 28 and 40 were investigated.
Results: Sodium benzoate at 0.02% and 0.04% concentrations had no effect on the growth of A. niger but the 0.1% concentration had the highest effect. Sodium benzoate at 0.02% had a better effect than the same level of PS on P. notatum. Potassium sorbate with all the concentrations had a better effect on A. niger: like benzoate, increasing concentrations of sorbate resulted in a higher preservative effect; PS at 0.1% had the highest effect. Combination 0.02 SB+ 0.08 PS and 0.08 SB+ 0.02 PS had the greatest and the least effects respectively.
Conclusion: Regarding the combinations, no synergistic effect has been observed, and no combination in the prevention of growth was better than the 0.1% concentrations of the two preservatives.
Significance and impact of the study: The better use of preservatives includes increase of antimicrobial spectrum, extension of pH range, reduction of toxicity, and prevention of microbial resistance.