Destruction of microbacterium lacticum escherichia coli and staphylococcus aureus during spray drying of milk part 2 effects of drying conditions
Chopin, A.; Mocquot, G.; Le-Graet, Y.
Canadian Journal of Microbiology 23(6): 755-762
Bacterial death during spray drying of skim milk is essentially related to the outlet temperature of the spray drier and the type of bacteria. Under industrial spray drying conditions, survival rates of M. lacticum, S. aureus and E. coli were 50, 2 and 0.002%, respectively. These rates may vary by a 104 factor for outlet temperatures between 65-105.degree. C. No simple mathematical equation could be derived to describe the relation between bacterial death rates and outlet temperature. Bacterial death is due in most cases to a heating effect during the last stages of drying when the temperature of the powder particle approaches that of the air at the outlet.