Assessment of airborne bacteria of milk processing unit complex associated environment

 The aim of this study was to identify the sources of airborne contaminants in milk processing units. 

 The aero-bacteriological investigation has been done fortnightly for a period of 1 year extramurally within the premises of milk processing unit complex with the help of modified two-stage Andersen Sampler. The raw milk samples were analyzed for total plate count and total coliform count. 

 The mean ± standard deviation of bioload of total coliform/mL, total plate count in million/mL, total airborne viable cultivable bacteria, Gram-negative bacteria, and the members of the family Enterobacteriaceae recorded were 3193.6 ± 220, 1673.33 ± 229.8, 3117.96 ± 1678.1, 46.33 ± 28.874, and 47.92 ± 33.5, respectively. Seasonal variations in airborne bacterial population were reported for this environment, high humidity and moderate temperature were the major factors for dissemination and distribution of Gram-negative bacilli. The temperature was positively and humidity was negatively significantly correlated with total airborne viable cultivable bacteria of this environment. There was no correlation established between bioload of milk and bioload of airborne bacteria. 

 The airborne bacterial bioload in milk processing unit complex environment areas were higher than the acceptable limit, with temporal and spatial variations. Mechanical activities were supposed to be the key factor governing aerosolization of potentially harmful bacteria which could contaminate the products. These results could be useful to establish a standard to the small-scale dairy processing units where monitoring of airborne bacteria were rarely adopted by dairy manufacturers in their routine quality control.