FOOD. Science. Technology. Quality

Food. SCIENCE. Technology. Quality

Food. Science. TECHNOLOGY. Quality

Food. Science. Technology. QUALITY




Effect of freezing and thawing process on microbiological safety of human milk


Human milk is recognised as a „gold standard” of nutrition for all newborns owing to its unique nutritional and immunological properties and because it is a source of microflora, which is a basis for shaping the human  microbiome. Activities of the Human Milk Banks contribute to the rationalisation of breast milk availability.  freezing is a method to preserve milk for keeping it stored. The research study attempts to assess the microbiological quality of unprocessed human milk and frozen and thawed milk using a method of air supply at 37 ºC. Analyses were performed to determine the following: total count of mesophilic aerobic microorganisms (TPC – Total Plate Count), Escherichia coli, Staphylococcus aureus, Cronobacter sakazakii, Listeria monocytogenes and Salmonella spp. Based on the results obtained, it was found that in the case of the total count of mesophilic aerobic microorganisms 30 % of the samples of human milk before freezing exceeded the maximum acceptable count of microorganisms, while in the case of thawed milk the samples covered 5 %. The count of Staphylococcus aureus was exceeded in 10 % of milk samples prior to freezing and in 5 % of the thawed milk. It was found that the freezing process and the properly conducted thawing process might constitute an important element in shaping the microbiological quality of human milk. In the analysed samples of breast milk there were detected no pathogenic bacteria: Listeria monocytogenes, Salmonella spp. and Cronobacter sakazakii. E. coli bacteria were also absent, which proves a good state of hygiene and compliance with the instructions of hygienic milk handling.


human milk, food preservation, microbiological quality, freezing, thawing