Current control measures effective against microbes in the plant air: study

By Stephen Daniells

- Last updated on GMT

Related tags: Bacteria, Microbiology, Hygiene, Listeria, Salmonella

The current control measures to limit the levels of microbes in the
air of pork processing plants are sufficient and effective,
according to Irish scientists.

Aerial counts of bacteria, including Staphylococcus, Listeria​ and Salmonella​ species were all in acceptable levels. The study, published in Food Control​, is an important vindication of the current control measures employed. "Overall, microbial levels in the air were low, which suggests that the current control measures such as the positive air pressures from high-risk to low-risk, internal separators and closed drains were effective in reducing the microbial contamination in the air of the plant,"​ wrote the researchers from Ashtown Food Research Centre, Teagasc, and University College Dublin. The most effect system to control food safety within a meat processing plant is hazard analysis critical control point (HACCP), which is reliant on other programs, including good manufacturing practices (GMP), good hygiene practices (GHP) and standard operating practices (SOP). Previously, the focal point of microbial assessment of the air in the meat industry has been the slaughtering plants, while meat processing plants have been largely ignored, said the researchers. "Air-borne contamination in meat processing plants is extremely significant due to the potential economic and health problems it may cause,"​ they wrote. "The microbial flora of the air has the potential to come in contact with meat and their presence can reduce the meats palatability and shelf life and increase its potential to cause food-borne illness." ​ To redress the balance the researchers analysed the air in a pork burger plant. Measurements of the total viable count (TVC), total coliform count (TCC) and levels of Staphylococcus aureus, Listeria​ spp. and Salmonella​ spp. were taken at the various production stages and at different times. A visual inspection of the plant was also performed to identify potential risks. The plant was arranged in three zones; raw, cooking and post-cooking, with the ventilation and air flow directed from the cooking area (high-risk) to the raw area (lower risk). "This design ensures the microflora in the air in the raw area cannot contaminate cooked burgers in the cooking area,"​ noted the researchers. Results ​ The report in the journal indicates that the highest TVC counts were observed in the cooking area, with 133 colony forming units per cubic metre (cfu/m3​). The blast chill area had the highest coliform counts (8 cfu/m3​), while Staphylococcus aureus counts were highest in the raw areas (8 cfu/m3​). "The higher levels of TVC, coliforms and Staphylococcus could most likely be attributed to people in the area, condensation and mechanically generated aerosol respectively,"​ wrote the authors. Interestingly, no detection of Listeria and Salmonella was made in the air in the plant. "To complement the air sampling method used on this audit and enable more definite conclusions to be made as to the cause of this, other contributing factors such as psychrometric properties of air, volume and turnover of air, movement of air etc. could be considered in future investigations,"​ concluded the authors. EU-wide improvements in saftey ​ According to official EU figures, 13 per cent of the bloc's food safety alerts in 2006 concerned meat and meat products. On the whole, the number of alerts was down five per cent on 2005, with tougher measures against illegal dyes and more harmonised criteria for detecting pathogens credited with the apparent improvements in safety. Source: Food Control​ (Elsevier) Volume 19, Issue 9, Pages 915-920 "An assessment of the microbial quality of the air within a pork processing plant" ​Authors: B. Byrne, J. Lyng, G. Dunne, D.J. Bolton

Related topics: Food Safety & Quality

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