Effect of oxygen on the keeping quality of milk: II. Effect of available oxygen on bacterial spoilage and oxygen uptake

SUMMARY The effect of limiting the amount of O 2 present in commercially pasteurized milk on bacterial growth and on the keeping quality of the milk was investigated. No increase in bacterial count of laboratory pasteurized milk during storage for 9 d at 5 °C was observed and O 2 consumption due to bacterial activity was low. In commercial pasteurized milk containing post-pasteurization contamination (PPC) growth of strict aerobes was encouraged by high O 2 content while that of coliforms was less dependent on O 2 level. The amounts of headspace (HS) O 2 consumed in milk with PPC growth were large. Reducing the dissolved O 2 content of commercial pasteurized milk stored in O 2 -impermeable containers without HS had little effect on bacterial activity and shelf-life.