DIY infused olive oil and food safety?

So, I found this bargain on a dehydrator. $20 at goodwill. For a big one, the screen / drawer type like an excaliber. It sat in the closet for months, waiting for an excuse. Finally, we had too many tomatoes for fresh eating. I blanched, peeled and sliced a few and dried them. Then I looked at 'em and said "Now what do I do with 'em?" I thought on it a few days and figured they'd look cool in a bottle of olive oil. Somehow our family $5 gift exchange for Christmas came to mind.

I rounded up some used glass spice jars and bought some olive oil. Remembered my home grown garlic and my wife's herbs. I just wanted to know if the rosemary and oregano should be dehydrated first. Internet searched my way into a rabbit hole. Good for two to three weeks (in the refridgerator) "they" said. Risk of botulism they said. Really? I always see bottles of oil with herbs and stuff in it just sitting on a shelf. But I don't wanna be the guy who shows up at the Christmas party and paralyzes (or kills) a cousin,  so I'm gonna take precautions.

So I put them in a pot of water and heated to 150°, then held between there and 140° for ten minutes. "They" said that would make the flavors infuse faster. I'd like to think I pastuerized them, but I don't think that's hot enough. They said don't go over 150° or the quality of the oil would be affected.

So I did more searching. Turns out you can freeze olive oil without hurting it. It allegedly turns back to the same clarity it started with. I need this to still be good in December, but the add ins are available now. So I'm planning to freeze it. I may wait until tommorrow in case someone offers me a better idea.

So, is the freezer my best option? Is this much caution necessary? What do you guys think?

You do need to be cautious with putting non-acidic foods such as herbs and garlic in oil and leaving it at room temperature for any length of time. Botulism contamination is from the spores growing from the dormant state into the live bacterial state in the anaerobic environment and producing the toxin. The spores are very heat resistant, which is why you need to use a pressure canner for low acid food canning so that you get the temperature above the boiling point. 140F won't cut it.

The bacteria doesn't grow well in an acidic environment, which is why you can do hot water canning with tomato sauce, many fruits, and pickled vegetables, but NOT green beans or other low acid foods in water.

Drying the herbs or garlic doesn't make any difference to the spores. They are the dormant state of the bacteria designed to survive dry, hot periods for years.

You could acidify the garlic and herbs then add to the oil, and I would recommend following guidelines online, such as Penn State. They have guidelines on making your own oil, including all of the needed details.

A few hours after heat treatment, the rosemary and oregano oils got cloudy. I'm hoping they just released moisture and a cold-warm cycle will seperate it. I put all four in the fridge this morning. Current plan is anything that looks useable goes in the freezer tonight or tommorrow. If the two don't improve, they get remade with dried herbs, then frozen. I guess I can't help that there's a clock on this labeled "botulism". For the garlic and tomato, it's been ticking for two to two and a half days. Almost a day for rosemary and oregano. I can, however use the freezer to hit snooze, so it will stay wound until December. That way it won't go off before Christmas. (Pun intended.)

Robin Katz wrote:You could acidify the garlic and herbs then add to the oil, and I would recommend following guidelines online, such as Penn State. They have guidelines on making your own oil, including all of the needed details.

I looked it up. I really want to keep the look of the whole herbs and whole garlic cloves, which that article discourages. I'll have to keep thinking about this. I may have to use these here, run the jars back through the dishwasher and start again. That article will be part of my thinking on this. Seems to be the most authoritative source I've looked at.

Your oils look beautiful!

I make dried calendula petal and separately, st john's wort flower infused oils for medicinal use.  The calendula infuses in a sunny window for six weeks and the st john's wort in the dark for just as long.  Neither are meant for food but in my reading I've never read a warning for oil infused with dried herbs? I just recently strained off the st johns wort and I leave the petals in the calendula oil...jojoba for both, and then store in the refrigerator.

I have heard that garlic is prone to botulism.  I've done dried tomatoes in olive oil and eaten them all winter from the jar in the refrigerator....no risk because of their acidity maybe?

Watching this thread with interest

I did a little more research. I found a food blog doing almost what I want to do. (If you check it out, be sure to read the comments.) My current plan is to use up what I've already made and start over. (They went in the fridge the day I last posted, and the freezer the next day.) Dry everything: herbs, garlic, tomatoes. Make the botulism do without water. Follow the blogger's recipe, which calls for heating the oil pretty hot. About 250°, I think. It also calls for acidifying the oil by mixing with vinegar. I can't imagine it will stay in solution, but it'll discourage botulism until the add ins are submerged in the hot oil. (Rinse the add ins in vinegar before pouring the solution over. My addition, from a tomato preservation video I watched.) Cool in the fridge before freezing so the bottles won't break. Instruct the recipient to refrigerate to use soon, or freeze to use later.

Correction: I just looked again. She calls for hot veggies, not hot oil. Think I'll try heating it anyway.

Seems like you have done  some reliable reaserch, and are taking reasonable precautions.

My sister is a trained chef,  her warnings have informed my choices in these matters.
I often make an oil and garlic paste for use on pizza.
Leftovers go strait into the freezer.
I recently made a kale flavored vinaigrette.
I keep the kale/ vinegar mix separate from the oil,  and mix them together right before use.

If I were going to make infused oil,  I would remove the herbs etc,  after a period of steeping.
Not as beautiful,  but less fussy.

I wonder if lactic acid fermentation of the herbs and veg would magnify the flavor and acidify them enough to prevent botulism.

Beginning again (draft #2):

Everything soaked 5 minutes in white vinegar, then dried. Planning to heat with the oil before bottling, cooling and freezing. Instructions will be refridgerate to use within the month, or freeze to keep longer.



Shown here are the rosemary, oregano and tomatoes, on their way to the dehydrator. Later, I remembered the garlic and gave it the same treatment.

I'm acidifying based on the food blog I linked to before, and the canning rule that allows canning acidic foods at 212°, but non acidic at (I think) 250°. I'm planning on heating with the oil to 300°- 350° for ~ten minutes to speed up infusion and to kill all the microbes as per this video:

Okay, I'm callin' it. I'm done with botulism whack-a-mole for the season. As in the last video I just linked, I was going to heat the infusion ingredients in the oil before bottling. I either learned why that guy didn't dehydrate, or why he didn't use tomatoes. Before my oil was up to temp, all my tomatoes were somewhere between brown and black. Not exactly burned, but unappealing. You know when you overcook bacon, and it's all dry? When you bite it, it turns to greasy sand in your mouth? The tomatoes are that texture. I've salvaged all the infused oil: I've strained it, and heated it to 350°. It's cooling to be rebottled. Gonna label it "Pizza Oil" and use it at home.

The $5 gift project just became an infused vinegar project. Rosemary, oregano, garlic and dill. I'll probably still freeze it. Hey, botulism, bring it.

I appreciate you sharing your journey of what worked, and more importantly, what didn't. This is the kind of information that is so useful to others.

I'll probably leave them out several days or a week. Anything that doesn't stink or change unhealthy colors gets frozen after that.

One week later. And that would be blue garlic. Take off the lids (if you can) and you'll find they're rusting. I put everything in the freezer today, to see how it responds. On the plus side, they all smell good. The new plan is to empty these bottles, give 'em back to my wife (if she wants 'em with rusty lids) for dried hebs, and remake bigger batches in bottles with corrosive safe lids, freeze 'em (if that test works out) and call it good.

Final iteration, day 1:



The bottles cost $1 each, a gallon of vinegar $2.44. I used way less than a gallon.

Final iteration, day 7:

They're in the freezer now.