Microbiological air quality of processing areas in a dairy plant as evaluated by the sedimentation technique and a one-stage air sampler

Abstract

The microbiological air quality at processing areas in a dairy plant was evaluated by using a one-stage air sampler, based on Andersen principles (impaction technique) and by culture settling plate technique, also known as sedimentation technique. Among these areas, milk reception, packaging, and pasteurization rooms were included. Rooms where cheese, yogurt, butter and "doce de leite" (Latin American typical treat made of concentrated milk and sugar) are made were also evaluated. For all processing areas, the numbers of mesophilic aerobic bacteria and yeast and molds recovered by air sampler were higher than 90 CFU•m-3-the maximum value recommended by American Public Health Association (APHA). In four of the six processing areas, the microbial numbers were higher than APHA's standard (30 CFU.cm-2 .week-1) according to culture settling plate technique. The results showed a difference (p<0.05) for the Staphylococcus aureus numbers (from <1.0 to 4.3 UFC•m-3) at processing areas. The numbers of microorganisms recovered by impaction technique were about 2 to 10 times higher than by sedimentation technique. The microorganism group determined at processing areas depended mainly on the technique. By the air sampler technique, it was observed the predominance of yeasts and molds and by sedimentation technique, of mesophilic aerobic bacteria. The increase of temperature at processing areas did not seem to affect the numbers of airborne microorganisms. On the other hand, the increase of air humidity showed a relation with the increase of microorganism numbers. The impaction technique should be chosen since it is better to recover airborne microorganisms, including pathogens.

Detection of airborne psychrotrophic bacteria and fungi in food storage refrigerators

“…Both of these public health problems and the microbiological spoilage of foods can be minimized by proper storage, the careful choice of raw materials, and proper food preparation (22 and mould counts determined in air samples from food processing areas are higher than those found in this stuy (5,28,40,43).…”

“…Penicillium is isolated frequently from both air and surfaces in food processing areas and was the most frequent genus found in meat and dairy products (40,43). In this study,…”

“…Airborne microorganisms can arise from many sources including air-conditioning systems, raw materials, and specific food production systems (3) and commonly include the propagules of micro-and macrofungi (31) along with bacteria and their resting spores. Airborne microorganisms can be electrostatic and have been shown to stick to and deposit on surfaces (48) and growth of these organisms can cause contamination in the air of refrigerators via aerosol formation (40). However, the extent to which airborne microorganisms inside food-storage refrigerators contribute to food contamination is largely unknown.…”

Biomonitoring the indoor environment of agricultural buildings

“…In addition, personal sampling has been used especially to characterize exposures during remediation [46], or to analyze total individual exposure to microbes [47]. According to some authors, passive sampling provides a valid risk assessment as it measures the harmful part of the airborne population which falls onto a critical surface, such as in the surgical cut or on the instruments in operating theatres [48][49][50]. This method is standardly used in practice in our condition.…”

Analysis of Air Quality in Selected Areas of a Poultry Processing Plant With the Use of a Microbiological Air Sampler

“…Salustiano et al (2003) mentioned that the impaction technique should be chosen since it can better recover airborne microorganisms, including pathogens. In addition of its simple operation and the reduced sample collection time, the primary advantage of the air sampler is the possibility to conduct a standardized evaluation of the regularly identical amount of air.…”