As it turns out, quite a lot.
A couple came into the store the other day and bought some of our olive oil with the intent of dropping a couple of cloves of garlic into the bottle to infuse it. It triggered a memory of a discussion I had with a supplier on garlic oil and the risk of botulism (although I didn’t remember the details at the time) so I urged them to ‘google’ garlic and botulism, because in case you weren’t aware, it’s ever so slightly deadly.
Botulism is a nerve toxin that causes muscle paralysis. It starts by attacking the muscles that control the eyes, mouth, face and throat, then spreads down the neck to the torso, arms and legs. It can also weaken the muscles that control your breathing, leading to respiratory problems and even death.
The toxin comes from spores made by clostridium botulinum (and sometimes clostridium butyricum and clostridium baratii) bacteria. These spores help the bacteria survive in hostile environments, and thrive in certain conditions, specifically low-oxygen (anaerobic), low acid, low sugar, low salt environments.
The spores are common in soil, and garlic, being a root vegetable, will inevitably have traces of soil (and therefore the spores). Put the cloves in oil and you have the ideal conditions for the botulism producing spores to proliferate.
So, if you want to make your own garlic infused oil safely, follow these steps;
- Sterilise your jar or bottle.
- Separate and peel the garlic cloves, carefully discarding the skins and any cloves that look or smell iffy.
- Pour your oil into a small saucepan and add the peeled garlic (and any other herbs or spices, see below). Warm gently over a low heat (as low as possible) so the oil gently warms to a slow, gentle bubble (85C or more).
- Cook like this gently for 15 minutes. The garlic will turn soft and slightly transluscent.
- Allow to cool then transfer to your sterilised jar or bottle.
Infused oil like this will keep safely in the fridge for up to 2 weeks, but don’t store at room temperature, and if left out for over an hour, discard.