Project: Methods of detection, elimination and control of Clostridium species in the red meat industry
Institution: University of Bristol
Clostridium estertheticum is a bacterium which can grow below 0°C in the absence of oxygen, and can cause spoilage ("blown-pack") in chilled vacuum-packed beef, lamb and venison. It forms spores which are resistant to hot water and many disinfectants, can persist in the meat processing environment, and are able to germinate and multiply in vacuum-packed chilled meat. This type of spoilage is responsible for significant losses in the UK red meat industry, first observed in the UK during 1987 in beef imported from the USA, it has since been found in spoiled vacuum-packed red meat produced in many other countries.
Packs spoiled by Cl. estertheticum usually contain gas and on opening have a strong vomit-like odour. The appearance of spoiled packs varies; some are severely distended within 2-3 weeks of packing, others never become severely blown. The causes of these variations are not clear, but may be dependent on initial numbers of Cl. estertheticum spores present and the other microflora in the pack.
The current methods used by meat companies to deal with this problem include meticulous hygiene with regular use of peracetic acid-containing disinfectants, and careful audits and checks on meat obtained from other companies. Rapid and sensitive tests are available to see whether Cl. estertheticum is present in the cutting room environment, in vacuum-packing machines or on meat http://www.langfordvets.co.uk/lab_pcr_ester.htm .
My PhD project has involved: investigating whether Cl. estertheticum is affected by heat-shrink treatment applied to vacuum-packs and whether this practice will accelerate or delay spoilage of contaminated packs; developing methods of detection for other cold-tolerant Clostridium spp. and investigating whether they cause spoilage in vacuum-packed red meat; exploring potential control strategies including the use of lactic acid bacteria and their metabolites to inhibit multiplication of Cl. estertheticum.