牛乳中 低溫細菌의 汚染度

Psychrotrophic bacterial concentrations in milk

Psychrotrophic bacterial counts were determined on raw milk, market milk and sweetened milk, and the effects of ultrahigh temperature treatments on psychrotrophic counts of raw milk were studied. The results obtained were summarized as follows. 1) Mean psychrotrophic counts of raw milk were: summer (Jun.-Aug.), 10×10⁵; autumn (Sep.-Nov.), 8×10⁵; spring (Mar.-May), 4×10⁵; and winter (Dec.-Feb.) respectively. 2) Psychrotrophic bacteria were not detected immediately after ultrahigh temperature treatments at 135℃ for 2 sec. of raw milk. 3) Psychrotrophic colonies were produced in both market milk and sweetened milk, and significantly higher counts were found at sweetened milk than at white market milk.