EFFECT OF TEMPERATURE OF LIQUID NITROGEN ON RADIATION RESISTANCE OF SPORES OF CLOSTRIDIUM BOTULINUM
Applied Microbiology
|July 1, 1965
Summary
Irradiating ground beef with gamma rays at -196°C required more radiation to inactivate Clostridium botulinum spores compared to 0°C. Lower temperatures reduced the lethal effect of radiation on bacterial spores in food products.
Area of Science:
- Food science
- Microbiology
- Radiation chemistry
Background:
- Clostridium botulinum spores are a significant concern for food safety.
- Gamma irradiation is a method used for food preservation.
- The efficacy of irradiation can be influenced by temperature.
Purpose of the Study:
- To investigate the effect of low-temperature gamma irradiation on Clostridium botulinum spore inactivation in ground beef.
- To determine the radiation dose required for spore inactivation at 0°C and -196°C.
Main Methods:
- Samples of ground beef inoculated with Clostridium botulinum spores were irradiated using Cobalt-60 at 0°C and -196°C.
- Apparatus included a Dewar flask and a relay system for precise temperature control during irradiation.
- Spoilage and toxin production were monitored after incubation at 30°C for 6 months.
- D(10) values were calculated in phosphate buffer and ground beef.
Main Results:
- Higher radiation doses were needed for spore inactivation at -196°C compared to 0°C.
- Spoilage was observed at lower doses (3.6 Mrad) at -196°C than at 0°C (2.7 Mrad).
- D(10) values in ground beef were 0.463 Mrad at 0°C and 0.680 Mrad at -196°C, indicating a 47% decrease in lethal effect at low temperature.
Conclusions:
- Low-temperature irradiation (-196°C) is less effective for inactivating Clostridium botulinum spores than irradiation at 0°C.
- The reduced efficacy at -196°C necessitates higher radiation doses for equivalent microbial inactivation in food.
- Findings have implications for optimizing radiation processing parameters for food safety and shelf-life extension.
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