Microbiological stabilization of fresh cow’s milk (<i>Bos taurus</i>) by ultrasonic pretreatment and low temperature thermal treatment

Abstract

The objective of this applied experimental research was to evaluate the microbial stabilization of pre-sonicated fresh milk by low temperature thermal treatment (≤60 °C), to reduce its perishability. Fresh milk was sonicated with an energy density of 0.5 kJ/mL before being thermally treated at low temperature (40 to 60 °C) for different times; The pre-sonicated and thermally treated milk was evaluated for its content of Total Mesophilic Aerobes (AMV) and Total Coliforms (TC), and the effect of the treatment on microbial populations was modeled using the Bigelow Model. It was determined that treatments between 40 and 45 °C generated population increases; but those treatments above 55.04 °C for AMV and 49.28 °C for CT initiated microbial inactivation processes, both temperatures being the lowest inactivation temperatures reported so far for fresh milk. The increase in thermal sensitivity would be linked to the production of sub-lethal damage to AMV and CT cells, which would allow fresh milk to be microbiologically stabilized at lower temperatures, reducing the deleterious effects of thermal treatments.