Contents   Index

Botulism and Fishery Products

Accompanying Notes
Table of Contents

By D. C. CANN

MINISTRY OF AGRICULTURE, FISHERIES AND FOOD

TORRY RESEARCH STATION

TORRY ADVISORY NOTE No. 22 (revised)

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Accompanying Notes

Defines botulism, refers to the occurrence of Clostridium botulinum in fish, and discusses the likelihood of outbreaks of botulism. Emphasises that the risk is remote although there is no room for complacency, and explains the precautions necessary, particularly with smoked fish products that may be eaten without further cooking. Note that reference to the incidence of botulism in the UK relates to the period prior to 1977. This Note is particularly relevant to Notes 5, 66, 74, 82, 88 and 93.

More recent advice notes that the growth of Clostridium botulinum is inhibited in foods stored below 10°C at salt concentrations above 3.5 % w/w in the water phase of the product, and that this concentration should therefore be the minimum in products intended for consumption without further cooking, such as cold-smoked salmon, and hot smoked trout and mackerel. For the safety of smoked fish products in general, it is recommended the products are kept chilled below 5°C throughout the distribution chain until eaten. Further information about the important distinction between salt content of the flesh and salt concentration in the water phase can be found in Notes 66, 74 and 82. The following practices should always be part of process control:

• Always use good quality raw materials.
• Completely eviscerate, wash and clean the fish properly.
• Ensure that the salt concentration is adequate.
• Ensure that drying is sufficient.
• Minimise the risk of contamination, or of cross contamination between raw material and product.
• When brining, change the brining solutions regularly to avoid the build-up of contaminating bacteria.
• Keep the product chilled below 5°C throughout the chill distribution chain.
• Provide appropriate storage and usage instructions for correct consumer handling.
• Pay particular attention to the need to prevent growth of Clostridium botulinum in vacuum packed products.
• When slicing, make sure that slicers are clean and can be cleaned.

Table of Contents

Introduction
What is botulism?
Clostridium Botulinum in fish
Outbreaks originating from hot-smoked fish
The possible danger in the UK
Time taken in days for experimentally inoculated products to become toxic
Smoked fish and botulism
How to control botulism
Summary

Contents   Index