Preservation of raw milk by the addition of carbon dioxide

Abstract

The effects of concentrations of 10–30 mM/1 of CO2 on the growth of psychrotrophic milk spoilage organisms were examined, both in untreated whole milk and in pure cultures of Pseudomonas fluorescens growing in skim-milk and broth. Spoilage of refrigerated untreated whole milk was found to be inhibited by the addition of CO2 and the effect was enhanced with increasing concentrations of CO2 and decreasing storage temperature. Experiments with pure cultures of Ps. fluorescens showed that the inhibitory effects of CO2 were not due to increased acidity or to displacement of dissolved O2, but to the presence of CO2per se which induced an increase in the duration of the lag phase of growth and had only a small effect on the logarithmic phase.