Effect of acidification of raw milk on psychrotrophic microrganims.

The contamination of raw milk with psychrotrophic micro-organisms has become a concern because they are able to multiply at refrigeration temperatures and produce heat resistant enzymes that affect the quality of milk and dairy products. The objective of this study was to evaluate the effect of acidification with CO2 and HCl on mesophilic and psychrotrophic bacteria present in raw milk during cold storage. Raw milk samples were acidified with CO2 and HCl 1N until pH 6,0 and stored at 5 °C for 10 days. The results showed an average reduction of 1 logarithmic cycle in the growth of psychrotrophic and mesophilic microorganisms in samples treated with CO2. Acidification with HCl showed no effect, indicating that inhibitory action was due to CO2 not by pH reduction. DOI: http://dx.doi.org/10.14685/rebrapa.v2i2.68