Investigating microbial properties of traditional Iranian white cheese packed in active LDPE films incorporating metallic and organoclay nanoparticles

Iranian white Cheese is a traditional type of cheese in Iran which is popular and widely consumed because of its pleasant organoleptic properties. To manufacture this cheese, raw milk is heated below pasteurization temperature, therefore, pathogenic and spoilage bacteria remain and cause several diseases in public health. In this research three kinds of nanocomposite films based on LDPE incorporated 1) Ag, CuO, ZnO, 2) Cloisite 15A, Cloisite 20A, Cloisite 30B that produced by extrusion method were used for packaging of the cheese and kept in 4°C during 28 days. Data analysis carried out using SPSS statistical software based on a completely randomized design. The results showed the nanocomposite films incorporated with metal nanoparticles had a significant decrease in the growth of Staphylococcus aureus, coliform, mold and yeast after 28 days, while, the growth of lactic acid bacteria decreased but less than control film. Sensory properties of cheese samples packed in active films were not significantly changed. However, physicochemical characteristics such as pH and moisture content were affected significantly by active films. Overall migration of packaging active films in food simulants were within amounts allowed by national and international legislations.