Effect of Different Somatic Cell Levels on Nitrogen Components of Yoghurt Milk and Probiotic Set Yoghurt During Storage Life

Nitrogen components of yoghurt milk samples and resulting probiotic set yoghurt were determined. Analyses included total nitrogen (TN), non-casein nitrogen (NCN), non-protein nitrogen (NPN), casein nitrogen (CN) and proteolysis index (PI). Yoghurt samples were analyzed 1, 7, 14 and 21days after production and storage at 5±1°C. TN, CN and PI contents of yoghurt milk samples with high Somatic Cell SC level were lower than yoghurt milk with low SC (p<0.05). NCN and NPN concentrations of yoghurt milk increased by the elevation of SC level, however differences between low and medium milk samples were not significant. During storage life, TN and CN contents of all yoghurt samples decreased significantly. NCN and NPN concentrations of probiotic yoghurt samples increased (p<0.05) after 21 days. It was concluded that SC level elevation in milk decreased casein as a percentage of true protein in the resulting probiotic yoghurt throughout storage for 21 days.