Homemade Pesto Sauce

[Chopstix]

How long would this keep in a jar in the fridge? I made some a week ago and it was still good today. I didn't add any cheese, just blended together garlic, basil, salt, pine nuts, and olive oil. It still looked and tasted fine today but I was just a little worried about botulism. Anybody? Thanks!

[ChefScotty]

Ten days, a year if you freeze some of it when you make it. Perfect time of year to make and freeze some.

[Gretchen]

I have found it to be what chef Scotty says. Even a quite long time in the fridge.

[Robo410]

It freezes well, it keeps a couple weeks if well oiled in the fridge...also push the plastic wrap right down over it to form an air barrier.

[Chopstix]

Thanks folks! That's a relief.

I'd like to understand though why the risk of botulism does not come into play here?

[cara]

the bacteria that produces botulism, Clostridium botulinum, is an anaerob bacterium... it can't survive in jar in a fridge, because there is too much Oxygen around...
if it would be canned and sealed air-tighten, there might be a chance, but you would see it, as the Clostridium produces a gas... there would be pressure on the can...

[Gretchen]

Originally Posted by cara

the bacteria that produces botulism, Clostridium botulinum, is an anaerob bacterium... it can't survive in jar in a fridge, because there is too much Oxygen around...
if it would be canned and sealed air-tighten, there might be a chance, but you would see it, as the Clostridium produces a gas... there would be pressure on the can...

That's not quite correct and it does bring up an interesting point. It is recommended that things like homemade garlic oil or herb oils not be stored for longer than a week because of the possibility of botulism. The anaerobic conditions are formed/provided in the oil. You may see the results of bacterial growth (in the case of Cl.botulinum, from spore activation) in an improperly processed can by a bulge in the can, but it is the toxin of botulism that is the poison and it is tasteless and odorless. It is inactivated by heat.

So, I guess we are just lucky with the pesto--and truth be told, I have used garlic and herbed oils in the past.

[cara]

okay, there are anaerobic conditions in the oil, you are right...
and the toxin is indeed tasteless and odorless, but there should be some gas bubbles to be seen, as the metabolism produces gas...
I must admit, I can't remember any botulism- intoxications from Pesto here in G....

[jennyema]

From Colorado State University ...

"A second important factor affecting the growth and toxin production of Clostridium botulinum is temperature. Proteolytic types grow between temperatures of 55 and 122 degrees F, with most rapid growth occurring at 95 degrees F. Nonproteolytic types grow between 38 and 113 degrees F, with an optimum for growth and toxin production at about 86 degrees F. For these types, refrigeration above 38 degrees F may not be a complete safeguard against botulism."


Pesto is certainly a botulism risk if not handled properly. Here's more

I'd freeze the pesto if you are not going to use it within 10 days or so.

[Chopstix]

Thank you for all that info! Think I'll keep my pesto batches small. I rather like the idea of pesto that's freshly-made as opposed to pesto that's thawed after months or a year in the freezer.