Inhibitory effects of potassium sorbate and ZnO nanoparticles on Escherichia coli and Staphylococcus aureus in milk-based beverage

Antibacterial substances have played a crucial role in food preservation. Herein, the inhibitory effects of potassium sorbate and ZnO nanoparticles (ZnO NPs) on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in milk-based beverages were examined through the determination of their minimum inhibitory concentrations (MICs) with an automated method for measuring bacterial growth curves. We revealed that the MICs of potassium sorbate and ZnO NPs against E. coli were 16.0 mg/mL and 8.0 mg/mL, respectively. While against S. aureus they were 24.0 mg/mL and 8.0 mg/mL, respectively. ZnO NPs demonstrated higher antibacterial efficacy compared to potassium sorbate. The combination of potassium sorbate and ZnO NPs showed an indifferent effect on E. coli, but an additive effect on S. aureus. The addition of 3 × MIC of either potassium sorbate or ZnO NPs resulted in a complete suppression of bacterial growth for 5 days. This study underscored the efficacy of potassium sorbate and ZnO NPs, either alone or in combination, in combating E. coli and S. aureus, highlighting their potential commercial utility in safeguarding milk-based beverages from spoilage.