A survey of four fluid milk processing plants for airborne contamination using various sampling methods

Abstract

Air in four commercial fluid milk plants was sampled for microbiological and nonmicrobiological particles over a 4-month period. An Andersen two-stage and Ross-Microban sieve samplers, a Biotest RCS sampler, and a Met-one laser particle counter were used to sample air. Air was sampled two to three times per day in raw milk storage, processing, and filling areas. Viable particle counts per 100 L air obtained with the Andersen sampler were 2.03 ± 0.41 (log10 Mean ± SD), 2.26 ± 0.57, and 2.41 ± 0.70 in raw milk storage, processing, and filling areas, respectively. These levels were significantly (p<0.05) greater than those obtained using the RCS and Ross-Microban samplers. Overall correlations of the Ross-Microban and RCS samplers with the Andersen sampler were r2 = 0.71 and 0.62, respectively. Correlations between Andersen sampler results and number of total particles greater than 0.5 μm were r2 = 0.36 in raw milk storage, 0.15 in the processing area, and 0.18 in the filling area.