Abstract

Influence of carbon dioxide on the activity of psychrophilic bacteria in raw bovine milk was investigated. ‎Also, some sensory characteristics of pasteurized milk which processed from raw milk ‎preserved by CO2 were studied. Firstly, effect of CO2 addition to raw milk was ‎compared with the acidification of raw milk to pH 6.2 with lactic acid and with control milk. The results showed partial inhibition in ‎psychrophilic microorganisms count in CO2-treated milk compared to both lactic acid-treated and control ‎milks during four days of study. Secondly, the effect of two low temperatures (4 and 10 °C) on reducing psychrophilic bacterial count was evaluated. The storage ‎temperature affected the growth of psychrophilic bacteria in CO2-treated milk; the lower temperature was the best; samples stored at 4 °C showed better inhibition in psychrophilic microorganisms count in comparison with the samples kept at 10°C. Thirdly, organoleptic ‎characteristics of pasteurized milk (65 °C/30 min) processed from raw milk treated ‎with CO2 showed insignificant differences (p?0.05) in taste, aroma and colour ‎between CO2-treated and control milks.