Control of blown pack spoilage in vacuum packaged chilled meats

Abstract

Blown pack spoilage (BPS) is an important food safety/quality issue facing the Irishbeef industry. BPS emerged in the USA in 1989 and was quickly followed byincidences in the UK, New Zealand and Ireland. Each spoilage event occurred incorrectly chilled batches (-1.5 to 4°C) of vacuum packaged (VP) meat after 2 to 4weeks and was characterised by the production of large volumes of gas, a putridsmell (H2S) with a metallic sheen on the meat. Meat spoiled in this way has nocommercial value and blown pack spoilage represents a considerable loss to meatprocessors. Prior to this research it was believed that there were 2 psychrophilicClostridium spp. (C. estertheticum and C. gasigenes) responsible for BPS and therewere no known control measures. The study initially undertook an epidemiologicaltraceability study in beef abattoirs to identify sources of BPS bacteria, beforefocusing on the development of specific control measures. Stages in the currentlyused VP meat processing chain, such as the heat shrinkage of the packs (a commonpractice during meat vacuum packaging) and the subsequent chill storage, wereassessed for their effect on the time of onset of overt spoilage. The study identifiedcattle hides, faeces and soils as the main reservoirs of BPS bacteria. A novel BPSClostridium spp. (strain TC1), subsequently named C. ruminantium, was discoveredand characterized for deposition in an international culture collection. The study alsoidentified thermal shrinkage as effecting spore activation and reducing shelf-life.Clostridial spore inoculation studies showed that the heat/no heat treatment/storagetemperature combination that gave the longest shelf life was ‘no heat’treatment/storage at -1.5ºC. In conclusion, the current study identifies thestrains/species that should be monitored during VP chilled storage, introduces the novel strain C. ruminantium, and discusses the pro/retroactive measurements need to be undertaken in order to control BPS in VP chilled meats.

Η διδακτορική διατριβή εξετάζει ένα είδος μικροβιολογικής αλλοίωσης κρέατος συσκευασμένου σε κενό αέρος, και συντηρημένου σε θερμοκρασίες ψύξης.