Nanosilver in dairy applications – Antimicrobial effects on Streptococcus thermophilus and chemical interactions

Milk spoilage continues to be a major problem. Incorporation of silver into milk packaging might solve this problem. We evaluated the antimicrobial and chemical effects of silver in milk. Antimicrobial experiments were performed by measuring milk acidification by Streptococcus thermophilus at temperatures of 43, 33 and 23 °C and concentrations of silver nanoparticles at 10, 50, 100 and 200 mg/L. Chemical interactions were investigated using potentiometric measurements. Ag⁺ interacted with milk constituents. Nanosilver was antimicrobially effective at all temperatures and at 100 mg/L. At least 5 mg/L are required by using AgNO₃. Practical use of silver for dairy applications is not expected, due to the required high silver concentrations.