Modeling of Escherichia coli and Listeria monocytogenes Inactivation in Human Milk With a Batch UV-C System: Effect...

This study was aimed at evaluating the influence of agitation intensity, initial temperature, and total solids content of milk on the inactivation of Escherichia coli and Listeria monocytogenes by UV-C radiation, with emphasis on a UV-C system in batches for human milk. The kinetic parameters of the inactivation of bacteria were estimated by GInaFiT and modeled to obtain a first-order model. Results showed that the initial temperature of the milk influencing only the E. coli inactivation and 4D reductions were achieved with UV-C dose between 42.7 and 54 J/L for E. coli and 29.2 and 48.6 J/L for L. monocytogenes, all under agitation conditions above 550 rpm. The UV-C dose to the first decimal reduction (δ) for both bacteria was approximately fourfold greater at 220 rpm than at 880 rpm. There is a statistically significant interaction between the effects of agitation intensity and total solids content for the prediction models of the p parameter of both bacteria. The intensity of agitation overcame the short penetration depth of UV radiation by exposing bacteria to irradiated areas more frequently in the inactivation of pathogenic bacteria in milk, and this batch UV-C system demonstrated potential for use in human milk processing.