Quantification of raw milk quality indicator microorganisms and microbiotic behavior during transport

Abstract

The refrigeration and transport of raw milk  bulk were some of the steps implemented by MAPA to improve the microbial quality of the milk produced in Brazil. However, milk storage under refrigeration temperatures are selective of  psycrotrophics microorganisms, that are able to  produce proteolytic and lipolytic heat-resistant enzymes that compromise the sensorial quality and the yield of dairy products. By quantification of mesophilic, psychrotrophic and proteolitic microorganisms, the present work aimed to evaluate the quality of raw milk produced at western region of Paraná and the effect of refrigerated transport on microorganism counts. Thirteen properties were evaluated and only at two properties the mesophilic counts were above the standard established by IN51. At 53,8% of the properties the psychrotrophic counts were above 6 log CFU.mL -1 and in twelve properties the the psychrotrophic count was more than the mesophilic count. The count of proteolytic psychrotrophs showed a variation between 3,11 log to 5,88 log CFU.mL -1. The refrigerated transport of milk to dairy industry did not change the mesophlic aerobes counts, however, the psychrotrophic counts and proteolitic strains incresead significantly. Consequently, to control the multiplication of the psycrotrophics group in the refrigerated milk, the contamination during the process production should be avoided.