Updated 05 May 2017

Beware of botulism

How many times have you dropped a tin of tuna on a supermarket floor and still tossed it into your trolley? Well, perhaps you should think twice before you do that.


How many times have you dropped a tin of tuna on a supermarket floor and still tossed it into your trolley? Well, perhaps you should think more carefully about what you might be eating.

Botulism can lurk not only in damaged tins, but in any canned goods.

Not easy to detect
Food poisoned by the botulism bacterium does not always appear unfit to eat. The toxin grows without emitting any gas, which causes the tin to blow up, nor will the food smell off.

Foods commonly involved in botulism outbreaks are vegetables like peas, peppers, corn, lima beans, green beans and mushrooms, sauces, soups, meats, fish or poultry that have been insufficiently heated during canning.

What happens to the body
In food-borne botulism, symptoms generally begin 18 to 36 hours after eating a contaminated food, but they can occur as early as 6 hours or as late as 10 days.

The bacterium causes muscle paralysis and symptoms of poisoning include double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth and muscle weakness that descends through the body.

Death results from paralysis of respiratory muscles.

Preventing botulism poisoning
Food-borne botulism often from canned foods, however, outbreaks of botulism from more unusual sources such as chopped garlic in oil, chilli peppers, tomatoes, improperly handled baked potatoes wrapped in aluminium foil, and home-canned or fermented fish.

Potatoes which have been baked while wrapped in aluminium foil should be kept hot until served or refrigerated.

The botulism toxin is destroyed by high temperatures, such as boiling the food for 10 minutes before eating it.

Honey – an unlikely source
Because honey can contain spores of the bacterium, it is not safe to feed children less than 12 months old any honey.

Disposing of poisoned food
To prevent food poisoning, discard all canned food that shows any signs of spoilage. This includes any cans that are bulging or swollen, or food from glass jars with bulging lids. Do not even taste food from swollen containers, or food that is foamy or has a bad odour.

Dispose of food in a way that prevents humans or animals from eating it.

Standards of food in SA
The South African Bureau of Standards (SABS) is responsible for inspecting tinned foods. Food technologists grade the food according to its standard.

The first category of food is classed as high consumable quality. The second classification is food that would be relatively fit for human consumption, but the quality of food is doubtful. This category is marked substandard – the same as the tin of fish which killed the Lawrence siblings.

Tinned food in supermarkets almost always falls into the first category. Consumers should make sure that the product they buy is labelled and a list of ingredients should appear. The can should be undamaged – no dents, leaks, swelling or rust.

Also, look out for coded cans, where lettering appears on the lids of tins. This contains the information necessary to trace the history of the product – the manufacturer, date produced, machine used etc. - (Health24)

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