Vol. 69, Nr. 1, 2004—JOURNAL OF FOOD SCIENCE FMS13 Published on Web 1/23/2004 © 2004 Institute of Food Technologists Further reproduction without permission is prohibited Food Microbiology and Safety JFS: Food Microbiology and Safety Relationship Between Aerosolized Microbial Load and Contamination of Fully Cooked Then Frozen Meat Products A.A. HELM-ARCHER, C.R. KERTH, W.R. JONES, T.A. MCCASKEY, AND D.E. CONNER ABSTRACT: The relationship between microbial loads in air and contamination of fully cooked meat products was investigated in a commercial processing facility. Air and product were sampled in the packaging area. No correlation existed between microbial counts from air samples and product samples (P > 0.05; r < 0.06). Micro- bial counts from air samples ranged from 0.30 to 2.54 log 10 colony-forming units (CFU)/500 L and from 0.30 to 3.78 log 10 CFU/g in the product samples. These data suggest that no direct relationship exists between microbial air quality and product contamination, but other environmental conditions may account for up to 1/5 of the variation in air contamination and 1/3 of the variation in product contamination. Keywords: air quality, beef, chicken, fully cooked product, microbial contamination Introduction A ir in meat-processing plants contains many microscopic parti- cles to which bacteria and molds can attach and move throughout a room. These molds and bacteria can cause spoilage, and contamination can occur at any step of meat processing, in- cluding during packaging. Safety is of particular concern with ready-to-eat products, especially with the potential of L. monocy- togenes to contaminate and to multiply at refrigerated tempera- tures. Economic loss, because of foodborne illness, and product loss, because of recalls and consumer confidence, are major con- cerns to the meat industry. Research conducted by Kotula and Emswiler-Rose (1988), Kang and Frank (1990), and Lutgring and others (1997) has shown that contamination of air in food-process- ing facilities is a problem, but little or no research has been done to determine whether air is a significant source of microbes on further processed meat. Therefore, more needs to be known about wheth- er a relationship exists between the microbial load on processed meats and the level of air contamination and the actions that need to be taken if a relationship does exist. It is well known that extrinsic factors, such as temperature and humidity, affect the growth of microorganisms. Most meat-process- ing facilities maintain processing room temperatures at or around 0 °C to reduce bacterial growth; however, many bacteria, including L. monocytogenes, have the ability to grow at these temperatures, which is especially significant in the production of ready-to-eat meat products. Because air is considered a potential source of con- tamination (Rahkio and Korkeala 1997), the association between production conditions and air quality, or product contamination, needs to be understood. The objective of this study was to deter- mine the relationship of the microbial load in the air and in a fully cooked meat or poultry product, and to determine the relationship between environmental conditions and aerosolized microbial load or product contamination in a meat-processing facility. Materials and Methods Air sampling and media Air from the cook line of a commercial meat-processing facility was sampled using an EM Science MAS-100 Eco ® microbiological air sampler (Gibbstown, N.J., U.S.A.). Meat products traveled via belt grills and conveyors through a raw area, cooking area, spiral freezer, and packaging area, all of which are separated from one another by walls. After the fully cooked product left the spiral freezer, it en- tered the packaging room fully exposed and traveled via a conveyor to a sorting machine where it was packaged and boxed. The packaging room was selected for sampling because product entering this area should contain low concentrations of microorgan- isms because by then the product will have been cooked and fro- zen. Preliminary air samples were taken to establish areas of sam- pling in the packaging room. The area at the conveyor and the area of highest employee traffic (the point at which most people are moving in and out of the room during the day) were chosen as sam- pling areas because they best represented areas where cross-con- tamination could occur. Media used for microbiological analysis was standard methods agar (Difco nr 247940, Sparks, Md., U.S.A.) for detection of total microbial colony-forming units (CFU). The air sampler was calibrat- ed to sample 100 L of air per min. The samplers were sterilized with 70% ethyl alcohol before sampling and after sampling. Two consec- utive 5-min samples were taken in each area every 45 min and were repeated for 2 to 4 sampling periods per day. Samples (n = 113) were taken over a 5-mo period from February to July. At the end of each day, samples were placed in a cooler and transported (ap- proximately 45 min) to Auburn Univ. and were incubated at 37 °C for 48 h. Colony-forming units were counted and analyzed as log 10 CFU/500 L of air sampled. Product sampling Processed meat samples (marinated beef or chicken fajita strip MS 20030418 Submitted 7/23/03, Revised 10/8/03, Accepted 10/28/03. Au- thors Helm-Archer, Kerth, Jones, and McCaskey are with Animal Sciences Dept., Auburn Univ., 209 Upchurch Hall, Auburn AL 36849. Author Conner is with the Auburn Univ. Poultry Science Dept., 236 Animal Sciences Build- ing, Auburn, Ala. Direct inquiries to author Kerth (E-mail: ckerth@acesag. auburn.edu).