Effect of high-pressure carbon dioxide processing on the inactivation of aerobic mesophilic bacteria and Escherichia coli in human milk

The effect of high-pressure carbon dioxide processing on inactivation of aerobic mesophilic bacteria and Escherichia coli ATCC 25922 inoculated in human milk was investigated. The effect of the ratio between sample mass and CO2 (1:0.2; 1:0.6 and 1:1m/m); depressurization rate (1, 5.5 and 10 MPa/min); and pressure cycling (1, 3 and 5) were the process variables studied. The best reductions in aerobic mesophilic bacteria as well as in E. coli (>6.0 and >5.0 log, respectively) were obtained with a ratio of 1:1, a depressurization rate of 10 MPa/min, and one cycle of pressurization/depressurization. The depressurization rate was found to be an important variable in the inactivation process. The results suggest that high-pressure carbon dioxide processing can be applied to human milk as a safe alternative to the pasteurization employed in human milk banks. RESUMENEl presente estudio se oriento a investigar el efecto de la utilizacion de dioxido de carbono de alta presion en la inactivacion de bacterias aerobias mesofilas y Escherichia coli ATCC 25922 previamente inoculadas en leche humana. Durante el proceso se analizaron las siguientes variables: ratio entre la masa de muestra y el CO2 (1:0,2; 1:0,6 y 1:1 m/m); tasa de despresurizacion (1, 5,5 y 10 MPa/min) y ciclo de presion (1, 3 y 5). La disminucion mas pronunciada de bacterias aerobias mesofilas y de E. coli (>6,0 y >5,0 log, respectivamente) se logro empleando una ratio de 1:1, una tasa de despresurizacion de 10 MPa/min y un solo ciclo de presurizacion/despresurizacion. Se comprobo que la tasa de despresurizacion constituye una variable importante para el proceso de inactivacion. En este sentido, los resultados permiten constatar que puede aplicarse dioxido de carbono de alta presion a la leche materna como alternativa segura a la pasteurizacion utilizada en los bancos de leche humana.