*Updated to contain even more safety information*
Important note: This is NOT a tutorial for canning tomatoes in oil, since there is NO way to do that at home safely. I am not recommending that. Removing all the air from the covered tomatoes would create an environment for botulism to grow (low acid + no oxygen). This simply shows how you can cover completely dried tomatoes with oil (and NO other ingredients), screw a lid on and store at room temperature.
The picture above shows how I’ve stored my dried tomatoes for years: in a vintage canning jar covered in olive oil and sitting in a kitchen cabinet. I’ve found them much easier to use this way: cut up in Italian pasta, over salads, and in dips, just to name a few.
I learned this technique by reading a well-know local food preservationist/writer, Jan Roberts-Dominguez in the Oregonian in the 1990’s. I actually taught myself to can using some of her articles and many of her recipes are my favorites even now.
But, here’s a note on safety: Many of you know I’m big on food safety, and I don’t do things based on the “I’ve done it for years and it’s never killed anyone” train of thought. However, this is a time-honored preservation technique that I feel good about for two reasons: tomatoes are naturally acidic (and I never add any fresh garlic or herbs), and I dry them until they are pliable, but no liquid comes from them when I test them with my fingers. I also, as per Ms. Dominguez’s recommendation, dip them in red wine vinegar to help extend their shelf life (and just so happens to increase the acidity).
However, about a month ago, I came across a newsletter that said the National Center For Home Food Preservation was no longer recommending storing dried tomatoes in olive oil. Why?
“Preserving tomatoes in oil is currently not recommended. Oil may protect botulism organisms trapped in a water droplet. Furthermore, oil may have a deleterious effect on lid gaskets and the at least one manufacturer of home canning lids recommends against it.”
You can imagine I was NOT happy with this. Especially since:
- The tomatoes are dried and don’t contain “water droplets” and
- The oil doesn’t touch the lids and I don’t use canning lids- I use vintage metal/plastic lids.
But mostly I wasn’t happy with this because when I tried to research this new recommendation, I wasn’t able to find any other site or research to back up this claim.
So I emailed Ms. Dominguez (hey, I’m a fan…) and asked if she had heard this and what her thoughts were. She had not heard this and basically said that if the tomatoes are truly dry and not packed with any fresh herbs or garlic there should be no problem. The vinegar dip she recommends also helps tip the acidity level.
So there. I’m still going to store my dried tomatoes this way, but I am giving you all the information I have at this point so you can make your own informed decision.
But let me tell you- these are sooo easy and tasty and a fraction of the cost of store-bought.
Not that I’m trying to sway you or anything.
9/3/11 update: I found this information that mirrored my own from the 2010 book, How to Store Your Home-Grown Produce: Canning, Pickling, Jamming, and So Much More by John and Val Harrison:
For years we stored in oil by simply placing the produce in a sterilized jar and filling the jar with oil, agitating to get any air bubbles out before sealing…when we published this on our website we were deluged with emails warning that we could get botulism from this…
When we researched this…we discovered that it was first mentioned on a Canadian website in reference to an outbreak of botulism from a restaurant…this was picked up and repeated…until it became a fact as far as casual searchers were concerned.
(We) decided to consult a food scientist directly. He explained that there was a theoretical risk that small droplets of water adhering to the vegetable would provide a growing medium for botulism. He couldn’t quantify the risk, not being a statistician, but comparisons with being struck by a meteor…were mentioned. He wouldn’t go on record as saying it was safe, although he said he would have no concerns personally about using the method.
The authors go on to say that they tired of the endless arguing on their site, so they now only recommend a “hot oil” method (whereby you heat the oil to 140 degrees before pouring it on the tomatoes and sealing), though there is some loss of flavor.
So now you are able to make an even more informed decision- you may heat your oil or not as you use your own common sense and experiences. As for me, I’m glad to know I can feel good about continuing to store my dried tomatoes this way.
I use only plum tomatoes for dried tomatoes to store in oil. If I were going to dry them crisp and make tomato powder, it wouldn’t matter as much.
I wash them, cut the top core off and cut them in half. I then remove as much of the seeds as I can.
It sounds tedious, but goes rather quickly. I line them up on my dehydrator tray, cut side up. This is important, otherwise you’ll get a lot more juice run-off as they dry and the cut side would stick to the tray, making them harder to turn as they dry.
As you can see, I really pack them in there because they shrink as they dry.
I dry at the manufacturer’s recommended 135 degrees and I don’t look at them for about four hours. That’s when I do the first switch: I turn them over and turn the trays around. None are usually dry yet, except maybe a few really small ones.
Let dry for another 1-2 hours before checking again. At this point, there will be some dry ones and you’ll need to remove theses and continue drying the rest.
This is what they should look like:
Dry and leathery with no moisture coming out from them when you push them with your fingers. You should be able to bend them like this.
If some get a bit crisp, it’s OK, but don’t let them all get that way- there’s no amount of oil that will soften them up again.
While the others continue to dry, start putting the dry ones in a jar. First, fill a little bowl with red wine vinegar and grab some tongs.
Dip the dried tomato halves into the vinegar and then let the vinegar drip for a minute before placing in the jar.
Continue dipping, letting them drip, and placing in the jar until all the tomatoes are gone.
Add olive oil to the jar until the tomatoes are covered. This is quite a bit of oil, but you will be able to use the oil in salad dressings and such as you use the tomatoes.
It’s not like it’s wasted or anything.
Make sure the tomatoes are completely covered in olive oil.
When the next bunch of tomatoes are dry (they never dry all at once, since they are all different sizes and thicknesses…), just continue to “dip and drip” each one in the vinegar and place in the jar, covering the new additions with more olive oil.
When the jar is full, store it in a dark, cool place.
Hopefully where you can reach it easily, because you will probably be using these a lot.
This is linked to:
Recipe Swap Thursday @ Prairie Story