There are so many various ways you can infuse olive oil and there are just as many posts floating around the web telling us about them. Some heat the oil, while others just throw it all together in the bottle and call it a day, some leave in the ingredients in, others strain them out before bottling. I have done a lot of reading and no matter what method you choose, there are a few concerns we have to take into account when making infused olive oils.
When using fresh ingredients that haven’t been dried, there is always a concern of Botulism, but most especially with garlic-infused olive oil. Clostridium Botulinum is a bacterium found in most soil and since garlic, being a root vegetable, is ripped from the ground, traces of this deadly bacteria are still left clinging to it. Since Botulism is an anaerobic bacteria (meaning that it thrives in an environment lacking oxygen), it dies in the presence of oxygen. Olive oil essentially seals out oxygen and when you mix food in with the oil, you have an ideal breeding ground for these potentially deadly bacteria.
Commercial grade garlic infused olive oils are (usually) prepared with an acid or preservative of some kind to preserve the garlic and protect if from growing harmful bacteria. At home, we could add some type of acid to the garlic oil mixture if we figure out the pH levels and all that, or to just be extra safe, we can simply strain out the garlic from the oil and store the infused oil in the refrigerator, consuming it in less than 1 month’s time. When leaving the garlic in the oil, the main concern is that toxin production has been known to occur even when a small number of C. botulinum spores were present in the garlic. When the spore-containing garlic is bottled and covered with oil, an oxygen-free environment is created that promotes the germination of spores and the growth of microorganisms at temperatures as low as 50 F. Scary stuff. So strain that garlic out, kids or if you are leaving it in, eat your garlic oil within a day or two!
Besides the garlic, I tend to prefer to use dried herbs and spices for my infusions. Dried herbs in oil are less of a safety concern because of their low water activity which makes conditions less favorable to growth of C. botulinum. When using fresh, whole herbs, since they look so beautiful in the bottles, I simply dehydrate them myself, so they can stay whole but it is safe to bottle with the oil.
So now that I have effectively
scared educated you, let’s move on to this how-to!
Infused Oils Using Dried Herbs, Vegetables, etc.
Heat the olive oil to 180°F in a pot over a medium/low heat. Remove the oil from the heat and pour the hot oil over the dried additives, let cool, then pour into your container and seal tightly. You can strain the ingredients out or leave them in, that’s up to you. If you don’t plan to leave the ingredients in the oil when you bottle it, you can also add them to the oil as it’s heating up, to maximize infusion time and the flavors being released.
Store infused oils containing dry garlic, vegetables, and/or herbs in a cool, dark place. This helps keep the fat from going rancid. Rancid oils does not look or smell any different. Eating rancid oils will not make you sick, however it can affect you long term and has been linked to cancer and early aging. Do not store for more than three months. After three months, throw away any unused oil.
Infused Oils Made with Fresh Herbs, Garlic or Other Fresh Items
Wash all the ingredients going into your oil and let them dry as much as possible – preferably overnight. You can also use a dehydrator on a low temperature, if you have one. Remember bacteria can’t grow in the olive oil itself, but it can grow in the water left on the ingredients going into the oil.
Heat the oil to 200ºF and add the fresh ingredients and allow to cook in the olive oil for about 3-5 minutes. Then remove from the heat, strain out the fresh ingredients and pour the infused oil into your bottle, tightly cap and allow to cool. Once cooled, store in the refrigerator.
Store oils made from fresh ingredients in the refrigerator and use as soon as possible, but definitely use within 1 month. Take the oil out from the fridge and allow it to come to room temperature for about 20 minutes before cooking with it.
Most importantly, always choose a high quality extra virgin olive oil from The Mighty Olive and whether fresh or dried, always opt for the highest-quality, organic (when possible) ingredients for infusing.
Be sure whatever bottles and containers you are using are well cleaned and thoroughly dried.