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I grow basil and I have enough that I would like to can some pesto sauce.

I have tried to find a way to can it but I keep hitting a wall.

I would like to give a few cans of pesto to people for Christmas.

Can anyone help me?

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5 Answers 5

I've never seen canned pesto, nor do I know if there is a way to do it safely. I will propose an alternate solution. Have you thought about freezing it? I've had pesto given to me as a gift before, but it was made as normal then frozen in a canning jar. It worked great.

Did some more digging and eventually came across this, from the National Center for Home Food Preservation. In summary, the oil and herb mixture is too low of an acid to prevent development of nasty bacteria.

See similar questions regarding storing/canning stuff in oil for more about why it might be dangerous: - Garlic Infused Oil - Peppers and Oil

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Canned pesto does exist, that is how it is normally sold in shops, at least in Europe. –  nico Sep 11 '12 at 5:33
    
A frozen Christmas gift? Now that is a new one on me! Pack it in snow for the ultimate White Christmas :-) –  TFD Sep 11 '12 at 6:29
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Definitely freeze it, and consider giving basil infused oil or vinegar (or something else) as a gift instead. –  lemontwist Sep 11 '12 at 13:18
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@badp Bottling and canning are basically the same thing - you make sure it's sterile and seal the environment. And canning at home refers to glass jars, not metal cans. –  Jefromi Sep 11 '12 at 17:43
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@Aaronut Correct canning = bottling + canning in North America. How many people own and use a home canning machine though? Last time I checked you couldn't can without one? Only place you can get them here is in a Museum! Bottling can be done with recycled jars and lids over and over again. Yes the cooking part and result is the same, but that's like saying riding a bike and driving a motorcycle is the same :-) –  TFD Sep 12 '12 at 2:06

I've never canned pesto, but I always make a big batch and freeze it when the threat of the first frost comes:

  1. Make pesto, but leave out any cheese
  2. Freeze ice cube trays or other small containers**, with a sheet of waxed paper pressed on top (to prevent signficant oxidation)
  3. After 2-3 days, release from the container, and put into a zip-top bag, squeeze out the air, and keep in your freezer.

When it comes time to use, take a portion out, and either defrost in the microwave, or toss it in the hot pan after draining the pasta, then stir in the hot pasta to melt it (turn heat to low if you've still got major frozen bits), and stir in your cheese.

** Beware of plastic ice cube trays, as you can easily stain them and leave a lingering garlic flavor. I keep two trays that I use for freezing pesto & stocks, but when I do large batches at the end of the season, I use muffin pans.

As an alternative ... you might be able to can basil oil, where you blanch the basil, then simmer it in olive oil, and strain it before putting up. (I keep mine in the fridge; I've never tried canning it). You can then use it in various dishes, including pesto (using flt leaf parsley for the green, which you can get more easily in the winter). Don't try to make a garlic-basil oil, or you'll have those same botulism risks.

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I think it is mainly the bacteria Clostridium botulinum that you need to watch out for, since it can come from many vegetables and can develop toxins in an anaerobic environment (e.g. in olive oil). It is also not visible and does not alter the taste of the food, and the toxin is one of the most potent natural toxins, so not a bacteria to do any trial and error with. Look for ways of inactivating the spores or lowering pH or adding salt to hinder the growth. I guess that's what the food industry does with their canned pesto. UHT treatment or anything like that.

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I've long wondered this, too, and your question prompted me to do some digging. This article at eHow seems to indicate that you CAN indeed pressure-can pesto if you leave out the olive oil in the recipe, and then add the oil in when you cook with it:

http://www.ehow.com/how_8323914_can-pesto-sauce.html

I also ran across a random comment in another thread by someone who claims to have been using a regular pressure-canning process for his pesto (including the olive oil) "for years" now with no issues. I think the eHow article and process is interesting. I'm not sure why leaving out the olive oil would be critical, but it's an interesting note.

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Leaving out the oil is critical because a large percentage of oil means the pH is high. –  lemontwist Sep 11 '12 at 14:17
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@lemontwist the rest of the ingredients in pesto are not necessarily more acidic than the oil. They certainly are not acidic enough to create a botulism-safe environment. The point of leaving the oil out can better be explained with the air which will be left mixed with the pesto, as botulism bacteria are anaerobic. I still don't know if this is enough to reduce the risk of botulism to officially approved levels, and of course a single person can can using unsafe practice for years without experiencing a problem, but you never know you won't be the one to be bitten by bad practice. –  rumtscho Sep 11 '12 at 15:28
    
@rumtscho, I agree. What I meant to get across was that with the oil in there as the primary liquid the pH definitely won't be low enough, vs. if you used vinegar as the primary liquid it wouldn't be as much of a problem. –  lemontwist Sep 11 '12 at 20:34

I think that commercial producers must dehydrate the basil first. By eliminating the water before you mix it with oil you would eliminate the risk of mold growth. Then they can use the oil as a preservative. No oxygen permeates the oil to reach the basil after pressure canning it. Once you open it of course you would expose it to air and it would have to be refrigerated. I make herbal infused oil and this it the rule of thumb I follow: dry herbs for oils, fresh for alcohol. There is no spoilage ever. I think I will freeze some and dehydrate the rest to make it the same way I would make an infusion.. with garlic, pine nuts, and Parmesan!

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the main risk with pesto is that botulism, and botulism prefers a low or no-oxygen environment. –  SAJ14SAJ Jul 23 '13 at 22:47

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