However, homemade flavored oils have earned themselves a nasty little reputation over the last few years, and not undeservedly so. There have been some documented cases of botulism resulting from flavored oils gone bad. But you needn't worry about such things if you follow some basic safety precautions:
- The first and simplest rule is to make flavored oils as you need them. I typically don't make more than 1/2 cup at a time and I do my best to ensure we use it within one or two weeks.
- Store flavored oils in the fridge. Though this does cause some oils to solidify, it's really not that big of a deal. Solid flavored oil can be used much like butter - spread on a peace of bread or set to melt in a pan. If you don't want solid oil, just set it out at room temperature and your flavored oil should resume liquid form in under an hour.
- Be clean. Sterilize your jars, wash your paws, and don't forget to clean off your flavoring agents (herbs, berries, etc.).
Here's a basic formula for making flavored oil from How to Cook Everything Vegetarian by Mark Bittman:
Makes: 1/2 cup
Time: 20 minutes, plus time to cool
Select ONE of the following:
- 1/4 cup washed and dried fresh herb leaves: rosemary, thyme, bay leaf (dried is okay), tarragon, marjoram, oregano, etc. OR
- 1 tablespoon whole spice: star anise, peppercorn, cloves, allspice, nutmeg, chiles (dried), etc. OR
- Aromatics: 2 garlic cloves, lightly crushed, or 2 tablespoons ginger slices, or roughly chopped shallots or scallions, or celery leaves, or a combination
- a pinch of salt
- 1/2 cup extra virgin olive oil or neutral oil, like grapeseed or corn
- Combine the flavor ingredient(s) and the oil in a saucepan and turn the heat to low. Warm gently until the mixture sizzles, then continue to cook until the oil is very fragrant, another minute or two.
- Cool, then strain into a clean bottle or other container. Refrigerate and use within a month or, at the most, two.
- Use good quality oil, but not the imported stuff you have take a second mortgage out to purchase.
- Don't flavor oils with ground spices or herbs. These flavor oil so quickly, you may as well do it in the pan when you need it. It's not worth flavoring oil in advance this way.
- If you want to give flavored oil as a gift, refrigerate it. Inform the recipient the oil is perishable and to keep it in the fridge and use it within a month or two at the very most. Mark the oil with all the pertinent information including your recommended "use by date" counting forward from the day you made it.
- Pair oils and flavors by cuisine combinations. For example, rosemary and olive oil go together in Mediterranean cooking while star anise and peanut oil are often paired in Asian cooking.
- When in doubt, use a neutral oil.