A food truck in southern Italy recently became the centre of a deadly health scare. A food-borne outbreak linked to preserved vegetables killed two people and sent more than a dozen to hospital.

At the same time, the UK’s Food Standards Agency warned shoppers to avoid jars of broccoli from a specific batch code, fearing they too could contain the same hidden danger, Clostridium botulinum, the bacterium that produces the toxin responsible for botulism – one of the deadliest food-borne illnesses known.

The canning process removes air from food and seals it tightly, creating an oxygen-free (anaerobic) environment. This is normally what keeps food safe for long storage – but it also creates the perfect conditions for C botulinum. Unlike many bacteria, it doesn’t need oxygen to grow.

Its spores, which are commonly found in soil, can survive cooking and processing. In low-acid foods such as broccoli, green beans, corn, beets and peas, if the canning process isn’t hot enough or long enough, those spores can “wake up”, multiply and release their toxin. Because the toxin is invisible, tasteless and odourless, contaminated food can look and smell perfectly normal while being deadly.

Botulism is rare but extremely serious and even a........

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