INFLUENCE OF CARBON-DIOXIDE ADDITION TO RAW-MILK ON MICROBIAL LEVELS AND SOME FAT-SOLUBLE VITAMIN CONTENTS OF RAW AND PASTEURIZED MILK

The effect of the application of CO2 to extend the cold storage of raw and pasteurized milk on the content of fat-soluble vitamins of milk w as investigated. CO2-treated milk (pH 6.2) was compared with a control (unacidified) milk. CO2-treated and control raw milk samples were sto red at 4 degrees C for 4 days. CO2-treated milk was then vacuum degasi fied, and both control and treated samples were pasteurized and stored at 4 degrees C for 7 days. CO2 addition inhibited the growth of micro organisms in raw milk without affecting the stability of vitamin A (re tinol and beta-carotene) and vitamin E (alpha-tocopherol). Acidity and pH data indicated that subsequent vacuum degasification and pasteuriz ation on a pilot scale partially removed CO2, making milk acceptable f or liquid consumption. However, the residual CO2 present extended the cold-storage period of pasteurized milk by inhibiting bacterial surviv ors without detrimental effects on retinol, beta-carotene, and alpha-t ocopherol. Slightly higher (not statistically significant, p > 0.05) c oncentrations of retinol, beta-carotene, and alpha-tocopherol were det ected during cold storage in raw and pasteurized CO2-treated milk with respect to the control milk, which could be related to a certain prot ective effect of the CO2.