Distribution and quantification of bioaerosols in poultry-slaughtering plants

Four poultry-slaughtering plants (2 turkey, 2 duck) were investigated for airborne concentration of microorganisms, including mesophilic and psychrotrophic bacteria and yeasts and molds. Approximately 40 sites were sampled in each plant during four visits (fall, winter, spring, and summer) by using an Anderson N-6 Air Sampler containing either tryptic soy agar (for mesophilic and psychrotrophic bacteria), or Rose Bengal agar (for yeasts and molds). Sampling sites inside the plants were categorized into the following areas: shackling, picking, evisceration, post chiller, cut-up, portion packaging and whole bird packaging. Areas outside the plant were sampled as controls. Airborne microbial counts in each plant were highest in shackling areas and decreased toward the packaging areas. Bacteria were the most common airborne microorganisms identified. In general, mesophilic bacterial counts ranged from an average high of 6 log CFU/m(3) in shackling to an average low of 2.5 log CFU/m(3) outside the plant. Mean psychrotrophic bacterial levels were usually within 1 log unit (90%) less than mesophilic bacterial levels and ranged from 2.5 to 5 log CFU/m(3). Yeasts and molds typically represented only a small proportion of the microbial population and usually were between 2.5 to 4 log CFU/m(3). Air flow, distribution, temperature, relative humidity, and design of the slaughtering facility were all important factors affecting overall bioaerosol contamination. This study identified the sources and concentrations of bioaerosols that may affect product safety and shelf life. This information is useful for developing appropriate strategies for poultry-slaughtering plant design.