Effect of Different Temperatures on the Microbiological Status of Donkey Milk

Abstract

Summary Donkey milk is usually sold for human consumption directly at farms and agricultural households and it is used in the raw state because of its well-known medicinal properties. Sometimes, however, such milk has poor microbiological status due to inappropriate conditions during hand milking and storage. The aim of this paper was to examine the microbiological status of donkey milk exposed to different temperature treatments (refrigerated at 4 ℃ for 3 h, frozen at −18 ℃ for 1 day, and pasteurized at 80 ℃ for 10 minutes). The number of molds and yeasts, total viable count, Enterobacteriaceae, Escherichia coli, coagulase-positive Staphylococcus, and the presence of foodborne pathogens, including Salmonella spp., Listeria monocytogenes, and Campylobacter spp. were evaluated to estimate the microbiological status of donkey milk. As expected, freezing and pasteurization reduced the number of tested microorganisms, and no examined foodborne pathogens were detected. The total viable count was reduced by 0.64 log CFU/mL by freezing and by 2.23 log CFU/mL by pasteurization. The total molds and yeasts and total Enterobacteriaceae count were significantly reduced by pasteurization. In conclusion, frozen and pasteurized donkey milk is safer than raw milk. In order to be able to recommend the best temperature treatment before consumption, the effects of freezing and pasteurization on the quality and antibacterial properties of donkey milk have to be further investigated.