FOOD. Science. Technology. Quality

Food. SCIENCE. Technology. Quality

Food. Science. TECHNOLOGY. Quality

Food. Science. Technology. QUALITY




Comparison of microbiological quality of pasteurized, microfiltered and UHT milk


Increasing consumption of milk in Poland and aiming of producers to maximize the shelf-life of product, motivates to search for new methods to preserve. The production of pasteurized (72ºC/15–20 s), microfiltered, and consequently pasteurized (MF/P) and UHT milk was performed, in order to determine any difference in their quality. All samples were stored under refrigerated conditions. Pasteurized milk was examined for 9 days, MF/P and UHT for 23 days. Milk normalized to 2 % fat content was tested just after the production, and during storage in 3 days intervals. The following parameters such as: total bacterial counts (TBC), total count of psychrotrophs, number of Bacillus spores, anaerobic spore rods which reduce sulfates, gas producing anaerobic spore rods, number of heat resistant microorganisms were determined in raw milk, after processing and during storage. pH and ºSH were controlled during storage. Moreover, total bacterial counts (TBC), number of somatic cells, protein, fat and lactose content, temperature of milk freezing were evaluated, as a level of quality of raw milk. Raw milk, used for production, was in accordance with Order of Minister of Agriculture and Country Development from 18th of August 2004. During whole storage period, the presence of coliform bacteria, anaerobic microorganisms fermented sucrose, or anaerobic proteolytic bacteria did not occur. Titration acidity increased faster in pasteurized milk, expressed in ºSH. Sterilized and microfiltered milk had stable acidity, varied ca. 0,5 ºSH. After 9 days of storage, pasteurized milk had similar microbiological quality like raw milk, which was made from. MF/P and UHT milk had very similar microbiological quality, in 23rd day of storage they were suitable for consumption (TBC < 10cfu/ml and 1,1×101 cfu/ml, for MF/P and UHT milk, respectively). Results indicate, that application of physical process for removing microorganisms (microfiltration) and successive pasteurization, enables production of milk with microbiological quality as in sterilized milk, but with sensory properties of pasteurized product.


milk, microflora, pasteurization, sterilization, microfiltration