Can You Get Botulism From Pesto?

Garlic, a potential cause of botulism

Short answer
Yes, in the past, pesto has been responsible for botulism poisoning. However, the better food safety standards we have these days means outbreaks are vanishingly rare.

Long answer>Let's start with a quick science lesson. Clostridium botulinum spores are found on the surfaces of fruits and vegetables, although they are not in themselves harmful. Under certain conditions though, these spores can start to produce a highly toxic poison which, if consumed, can lead to paralysis, and in the most extreme circumstances, death.

Botulinum bacteria thrive in alkaline, anaerobic environments. If you were to put some garlic cloves (or any root vegetable) into a jar of oil and leave it on your kitchen worktop for a few days, you will have inadvertently created the perfect breeding ground for botulism toxins to multiply. These are toxins that cannot be detected by sight or smell.

Because garlic and oil are key ingredients in most pesto sauces, botulism is something that producers take extremely seriously. Thankfully, here in the UK we have incredibly high food safety standards and the risk of getting botulism from a shop-bought pesto is virtually zero.

It’s easy (and safe) for anyone to make fresh pesto at home. In fact, we actively encourage it. However, when it comes to making pesto that can be stored at room temperature for many months, it’s best left to the professionals unless you are 100% confident that you understand the science. In well-meaning but ill-educated hands, the combination of garlic and oil can represent a genuine danger to public health.

The way pesto producers ensure there is no risk of botulism is to ensure their sauces are both acidic and heat-treated. Some producers use preservatives too.

Botulism spores cannot produce toxins in acidic environments, so we ensure the pH of our sauces are always below pH 4.6. It just so happens that we love the flavour of citrus juices in our sauces, so in that sense it’s win-win!