Infrared Heat Treatment for Inactivation of Staphylococcus aureus

The efficacy of infrared heating for inactivation of Staphylococcus aureus, a pathogenic microorganism, in milk was studied to investigate the potential of this technology for milk pasteurization. S. aureus population was reduced from 0.10 to 8.41 log ₁₀ CFU/ml, depending upon the treatment conditions. The effects of infrared lamp temperature (536, 619°C), volume of the treated milk sample (3, 5, and 7 ml), and treatment time (1, 2, and 4 min) were found to be statistically significant (p<0.05). Complete inactivation of S. aureus was obtained in two cases within 4 min at a 619°C lamp temperature, resulting in 8.41 log ₁₀ CFU/ml reduction. Enrichment resulted in growth as some of the injured cells were able to repair. Further investigation of infrared heat treatment for longer treatment times (> 4 min) indicated that there was no growth observed following enrichment in most cases for treatment at a 619°C lamp temperature. The results demonstrated that infrared heating has an excellent potential for effective inactivation of S. aureus in milk. Further optimization of the process may result in a commercially successful milk pasteurization method.