INFLUENCE OF LACTATION STAGE AND STORAGE TEMPERATURE ON THE ACTIVITY OF LACTOPEROXIDASE ENZYME SYSTEM ON MICROBIAL LOAD OF RAW COW'S MILK.

This study was carried out to investigate the effect of using the lactoperoxidase enzyme system (LPS) on improving the keeping quality and increasing the shelf life of raw milk. Fresh milk samples were obtained after morning milking from Butana cows at different stages of lactations. The milk samples were cooled immediately before transported to the laboratory, where they were divided into two groups (control and treated), then each group was subdivided into four sub-groups and kept at 5±2°C, 13±2°C, 25±2°C and 37±2°C temperatures. All samples were subjected to microbial examinations (total bacterial count, psychrotrophic bacterial count, coliform count and yeast and mould counts), acidity and clot-on-boiling test during the period of storage. The results showed significant (P<0.05) variations between the control and LPS treated milk samples on total bacterial count, psychrotrophic bacterial count, coliform count and yeast and mould counts. Moreover the data revealed that cows' milk samples from different stages of lactation treated with LPS showed longer shelf life and better keeping quality during all storage degrees of temperature compared with the controlled samples under the same conditions. The study concluded that although the LPS activity is affected by the storage temperature of the milk, it is useful in prolonging the shelf life of raw milk. Hence it could be applied in hot areas like Sudan in order to utilize the huge quantity of the milk produced in the traditional systems. [ABSTRACT FROM AUTHOR]