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Effect of delayed evisceration on the microbial quality of meat
Abstract:
The postomortem invasion of muscle and other tissues by bacteria from the intestinal tract was studied with the use of radioactive tracers. The injection of 14C-labeled bacteria or spores into the intestines of guinea pig carcasses within 24 h of death resulted in the rapid spread of 14C throughout carcasses. When live bacteria were injected along with the labeled cells, it was not possible to isolate viable organisms from the body tissues if the living animal had been exposed to the bacteria. It appears that animals are immune to their normal intestinal flora and that this immunity persists after death; thus passage of these bacteria into the lymphatic system does not necessarily result in the presence of live bacteria in carcass tissues. It therefore seems that a delay of up to 24 h before evisceration would not lead to deep tissue contamination of the carcass by organisms usually present in the intestines. Further evidence for this hypothesis was obtained by showing that muscle and lymph nodes from uneviscerated lamb carcasses hung for 24 h at 20 C remained sterile.
Insights
Postmortem bacterial invasion from the gut into carcass tissues is limited. Animal immunity to intestinal flora persists after death, preventing deep tissue contamination for up to 24 hours postmortem.
Area of Science:
- Microbiology
- Food Safety
- Postmortem Autolysis
Background:
- Bacterial translocation from the gut into tissues postmortem is a concern for food safety.
- Understanding the timeline and extent of this invasion is crucial for carcass handling protocols.
Purpose of the Study:
- To investigate the postmortem invasion of muscle and tissues by intestinal bacteria.
- To determine the impact of pre-evisceration time on deep tissue contamination.
Main Methods:
- Utilized radioactive tracers (14C-labeled bacteria/spores) injected into guinea pig carcasses within 24 hours of death.
- Assessed the spread of radioactivity and isolation of viable organisms from carcass tissues.
- Examined uneviscerated lamb carcasses hung for 24 hours at 20°C.
Main Results:
- Radioactivity rapidly spread throughout guinea pig carcasses after injection.
- Viable organisms were not isolated from tissues if the live animal had prior exposure to the bacteria, suggesting persistent immunity.
- Uneviscerated lamb carcasses remained sterile in muscle and lymph nodes after 24 hours at 20°C.
Conclusions:
- Animal immunity to normal intestinal flora persists postmortem, limiting bacterial translocation.
- A delay of up to 24 hours before evisceration is unlikely to cause deep tissue contamination by endogenous intestinal bacteria.
- Findings support extended holding times for carcasses without compromising safety from gut flora.