The effect of different doses of UV-C treatment on microbiological quality of bovine milk

Abstract

In this study, a non-thermal technology for preservation with the use of UV-C (ultraviolet) was examined in bovine milk. After UV-C treatment, the counts of microorganisms naturally found in raw milk and counts in pathogen-inoculated UHT milk were determined. For UV-C treatment, a reactor with a variable flow rate (5 mL/min to 18 mL/min) and temperature range (4°–25°) was designed and the data were modeled using response surface methodology. After UV-C treatment, approximately 2 log decrease in total mesophilic aerobic bacteria count and approximately 4 log decrease in yeast-mold count were achieved in raw milk. For pathogen-inoculated UHT milk, Salmonella Typhimurium (ATCC 14028), Listeria monocytogenes (ATCC 19115), Staphylococcus aureus (ATTC 25923) and Escherichia coli (ATTC 35218) counts were decreased by nearly 2 log, 2.5 log, 2.5 log and 3 log CFU, respectively. Since high-dose UV-C treatment is detrimental to the sensory properties of milk, it can be integrated with existing pasteurization techniques with a reduction in pasteurization temperature rather than as a stand alone alternative to pasteurization of raw milk.