Will my infused oil spoil?

October 22, 2008 1:03 PM

Will an infused oil I make today, still be edible come Christmas?

I had to harvest the rest of my Rosemary yesterday, due to an impending hard frost. So, now I have a shopping bag full of the stuff.

One idea my wife has is to make-up a few bottle of rosemary olive oil to give to family at Christmas. This seems like a great idea. However, in researching the preferred processes, I keep running across warnings that herb-infused oils will spoil relatively quickly. With roughly two months to go until Christmas, I'm wondering if I should just forget it.

What say all? If I'm careful in my preparation, cleanliness, and storage, can I safely expect my rosemary oil to survive through the holidays?

Bonus question: For rosemary, would you suggest a heat infusion, or just put the herbs and oil in the bottle cold?

posted by Thorzdad to Food & Drink (13 answers total)

Keep it cool and it'll be fine. Oils spoil much, much faster when exposed to heat and light. Keep it in the 'fridge.
posted by paanta at 1:10 PM on October 22, 2008

I wouldn't risk the chance of botulism just to have some Christmas presents. Will you be fine? Most probably. However, as the article suggests, I'd think infused vinegars are a better idea.
posted by saeculorum at 1:15 PM on October 22, 2008

Could you freeze the rosemary? "Softer" herbs like basil and coriander can be frozen with no ill effect. That way, you could make the oil closer to the time, with less risk of spoilage.

I'd make a cold infusion. Heating up the oil will extract the flavour more quickly, at the expense of cooking it slightly.
posted by Solomon at 1:17 PM on October 22, 2008

It's impossible to say, botulism spores come from the soil and you can never be sure you got every last speck of soil off. I leave infused oils up to the pros, but rosemary infused red wine vinegar sounds like a great gift.
posted by TungstenChef at 1:22 PM on October 22, 2008

The worries about oils causing botulism poisoning have never been proven to actually happen in the real world, although many sources echo them. I prefer to act on medical fact, not worries.

BTW, you don't need to get every last speck of soil off. You simply need to heat it above the survival temperature of botulus spores. This is called pasteurization, and is a fairly routine part of the process of making most flavored oils.

Short answer: no/yes. (Not poisonous, will last past Christmas)
posted by IAmBroom at 2:43 PM on October 22, 2008

Oh FFS, enough with the botulism already. Every time someone wants to store some food the fucking botulism police come out. The 2006 Summary of notifiable diseases from the CDC (available in pdf here), shows that there are typically 20-30 cases a year, mostly from home canned foods and Native Alaskan fermented seafoods*. That's 900 cases over 15 years. In the same 15 years, the UK national lottery has created over 2000 sterling millionaires.

Don't panic. Clean the rosemary, dry it well, don't let any of it poke out of the top of the oil and refrigerate. Then enjoy at your leisure.

*(note: before the inevitable whining - home canning is typically wet food, and is different from storing in oil).
posted by Jakey at 3:22 PM on October 22, 2008 [4 favorites]

The worries about oils causing botulism poisoning have never been proven to actually happen in the real world, although many sources echo them. I prefer to act on medical fact, not worries.

BTW, you don't need to get every last speck of soil off. You simply need to heat it above the survival temperature of botulus spores. This is called pasteurization, and is a fairly routine part of the process of making most flavored oils.


Er, did you even do a Google search before posting?
Foodborne Botulism in the United States, 1990-2000

Home-bottled garlic-in-oil was associated with events in 1991 in California and in 1999 in Florida. In one of these events, the garlic-in-oil was prepared by using home-canning methods; the mixture was heated to a temperature insufficient to kill C. botulinum spores.

I'd love to see a peer-reviewed article debunking these cases, but until I do I remain unconvinced that infused oils don't cause botulism in the real world. The risk isn't just from botulism toxin either, it's also from botulism spores which aren't destroyed at boiling temps, they have to be put in a pressure canner or autoclave. Doing that really defeats the purpose of using fresh herbs to flavor an oil because that fresh herbal taste is destroyed under those conditions.

Oh FFS, enough with the botulism already. Every time someone wants to store some food the fucking botulism police come out.

You're right, it is really rare, possibly on par with winning the lottery. But in this lottery the prize is watching yourself become paralyzed, eventually suffocating because you can no longer move your muscles enough to draw breath. Is that really worth it for a bottle of rosemary oil? I know I can go to the grocery store any time and make herb infused oil whenever I need it for $1 worth of ingredients.
posted by TungstenChef at 5:22 PM on October 22, 2008 [1 favorite]

Here's a better link to the same paper:
http://www.cdc.gov/ncidod/EID/vol10no9/03-0745.htm

Which is amusing if you look at table 3, because you'll learn that there's one poor soul who got botulism from making peyote tea.
posted by TungstenChef at 5:37 PM on October 22, 2008

OK, I stand corrected.

However, given the odds against it, it's on a par with eating a deli sandwich from truck stop diners, or dining at a ChiChi's (when they were still around). No one thinks of those as unsafe, but they are on the same par for survival rates.

So, I buy that it can happen, but it's damned rare.
posted by IAmBroom at 7:56 PM on October 22, 2008

My experience with infusions of rosemary in olive oil is that they won't keep very well at room temperature for more than a few weeks, that they will keep for a month or two in the fridge, and that they will keep the entire winter frozen. My recommendation is that you freeze your infusion.
posted by ssg at 10:14 PM on October 22, 2008

Maybe you could make dried rosemary instead/as well.
posted by ambilevous at 6:19 AM on October 23, 2008

A few things help retard spoilage in herbal oils:

Let the herb dry out a little bit (a day) before you put it in oil. Also be sure it is not damp from rain when you pick it.

Add the oil from a Vitamin E capsule.

A drop of yarrow or other alcohol based tincture helps, too.

My guess: it'll be fine.
posted by Riverine at 4:09 PM on October 23, 2008

Response by poster: Well, there was a lot to chew on in these great replies. Frankly, I found all the arguments convincing and informative.

In the end, given the extended time-frame I was looking at between bottling and gifting, I opted to take as many precautions as I could. I dutifully washed-off what dirt there was on the fresh rosemary. After drying and placing in the bottles, I heated olive oil to the appropriate temperature and filled the bottles, completely covering the rosemary, then tightly corked the bottles.

Since these won't be given for another month, we really won't know of any botulism-related deaths for awhile. My own personal bottle has been problem-free, though.

Thanks all, again!
posted by Thorzdad at 1:32 PM on November 23, 2008