Investigation into the antibacterial behavior of suspensions of magnesium oxide nanoparticles in combination with nisin and heat against Escherichia coli and Staphylococcus aureus in milk

• We examine potential of MgO NPs alone or in combination with nisin for use as an antibacterial agent in the food.
• Increasing information can help in determining the necessary food processing conditions.
• Increasing information can help in producing a product of higher sensory quality.
• Increasing information can help in producing a product by lowered energy costs.
• Increasing information can help in producing a product with essential elements to human health.

The antibacterial activities of magnesium oxide nanoparticles (MgO NP) alone or in combination with nisin against Escherichia coli and Staphylococcus aureus were investigated. Synergistic antibacterial effects existed and at lower levels of nisin when compared to when nisin was used alone. Also the antibacterial activities of MgO NP in combination with other antimicrobials (nisin and heat) against E. coli and S. aureus were investigated in milk. A synergistic effect of MgO NP in combination with nisin and heat was observed as well. Scanning electron microscopy was used to characterize the morphological changes of E. coli after antimicrobial treatments. It was revealed that MgO NP treatments in combination with nisin distort and damage the cell membrane, resulting in a leakage of intracellular contents and eventually the death of bacterial cells. This is the first report describing the antibacterial activity of MgO NPs and nisin in milk. It leads the way to development of treatment combinations which could result in a decrease in pasteurisation temperatures and the level of MgO NP required for pasteurising milk and maintaining pathogen control.