Modification of Milk Proteins by Psychrotrophic Bacteria

Skim milk and casein were inoculated with psychrotrophic bacteria and held 5 days at 7 C. Samples then were removed and examined by anion exchange chromatography with diethylaminoethylcellulose in Tris-citrate-urea or phosphate buffer and stepwise addition of sodium chloride. Results of tests on cultured skim milk and casein, when compared to controls, revealed an increase in number of nitrogenous compounds that were eluted from the column before casein and a decrease in the amount of/3-and as-casein. Chromatograms of control and cultured whey proteins were similar, indicating that these proteins were unaffected by the psychrotrophic bacteria.