STORAGE STABILITY OF RAW MILK SUBJECTED TO VIBRATION
 
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Pol. J. Food Nutr. Sci. 2006;56(Special issue 1s):65–70
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ABSTRACT:
The aim of the present study was to determine the effects of cold storage (temp. 4 and 8°C) on some physicochemical properties and technological suitability of raw milk subjected to vertical vibration at various frequencies (10, 30 and 60 Hz). An analysis of the results showed that vibration increased milk acidity and negatively affected milk components. The process caused, among others, an increase in the levels of ionic calcium and free fatty acids, as well as protein degradation (an increase in the formalin number), which deteriorated the technological quality of milk (a decrease in thermal stability and ethanol stability, a shorter rennet coagulation time). The degree of these changes corresponded to an increase in vibrational frequency. Intensive lipolytic and proteolytic processes and enhanced acidity were observed during cold storage of raw milk subjected to vibration. This had a negative effect on the technological suitability of milk. The changes were less significant in the case of deep chilling (4°C).