Antibacterial Properties of Whey Protein Coating and Mentha aquatica L. Essential Oil on Coliform Bacteria in Iranian White Cheese

Background and Objectives: In this study, antibacterial effects of whey protein coating with Mentha aquatica L. essential oil on Escherichia coli, Enterobacter and Klebsiella pneumoniae in Iranian white cheese were investigated. Materials and Methods: Mentha aquatica L. essential oil was extracted using Clevenger apparatus. Mentha aquatica L. essential oil was added to each whey protein coating solution at 0.5, 1 and 1.5% concentrations. Whey protein treatment included cheese, bacteria and whey protein with no Mentha aquatica L. essential oil. Control treatment only included cheese and bacteria with no Mentha aquatica L. essential oil and whey protein. Minimal inhibitory concentration and minimal bactericidal concentration were assessed for the bacterial species. Antibacterial properties of the designed active coating system against Escherichia coli, Enterobacter and Klebsiella pneumoniae were assessed using direct cell counting and disk diffusion methods. Results: Mentha aquatica L. essential oil at 1.5% concentration at the end of Day 15 of storage at 4 °C inhibited growth of Escherichia coli, Enterobacter and Klebsiella pneumoniae up to 100, 64 and 18%, respectively. To achieve the highest growth inhibition of Escherichia coli, Enterobacter and Klebsiella pneumoniae, 1.5, 1 and 1% of the essential oil were used to preserve organoleptic properties of the cheese. Conclusions: Use of whey protein coating with 1.5% essential oil included no adverse effects on organoleptic, sensory and appearance characteristics of the cheese. Whey protein coating with Mentha aquatica L. essential oil inhibited growths of Escherichia coli completely and Enterobacter partially in Iranian white cheese.