Changes in milk microbiota and spore content during milk processing unit operations

Abstract

This research aims to investigate how the level and composition of milk microbiota, including anaerobic spores, are influenced by individual unit operations commonly used during milk processing. Samples were collected after different processing stages, from raw milk to microfiltrated, and pasteurized milk. Culture-dependent and -independent analyses were performed to follow the microbiota and anaerobic spore content changes along the process. In our study, we observed that the initial microbiological quality of raw milk impacted the final bacterial content, influencing the microbiota at each stage of processing. Separation and microfiltration, together with pasteurization, were identified as having the greatest impact on the composition of the milk microbiota and spore reduction, but during the microfiltration process, some bacteria and spores were able to pass the membrane. Furthermore, bacterial contamination at the separation stage and the presence of spores in the standardized milk due to environmental contamination were detected.