I have a very large basil crop this year for which I am extremely excited.
In addition to drying and putting that up for myself over the winter, I want to put up pesto for me. I especially want to ship some to my sister and a friend, both of whom are a bit far flung, in the refrigerated coolers I get some of my medication in.
I follow the standard recipe: Genovese basil, nuts, olive oil, Parmesan, garlic and a pinch of salt. In my experience, filling a small jar with pesto and floating some oil atop it keeps it from turning brown for a few days, but pesto rarely lasts around here for more than a two days.
Google searches, in every iteration of "preserve pesto basil, pesto long term, shipping, &c." are giving me conflicting answers. A few of the food folks I follow on social media say it can be done with a vacuum packer and then frozen. That makes sense, as there would be no oxygen in the container. Some suggest the ice cube tray method. Still, others say my quest is hopeless. I have no vacuum packer.
I am semi-familiar with using citric acid in canning, but wouldn't the addition of acid to the mix instantly brown the basil, rendering that ugly color? I may be putting it in canning jars, but I would never process it like I do vegetables. I have tried the ice cube tray method, but the result is ugly-looking sauce that I feel would be difficult to ship cross-country. Freezing it ruins the texture anyway, in my opinion, likely because the Parmesan is not very freezer-friendly. (Maybe?) When I look at the ingredients on jars of pesto at the market, I see several preservatives, none of which I understand or want in my finished product, even if I did understand them or could get them…
I have seen this, but I am not sure it applies. How do you prevent pesto (basil) from becoming bitter?
Is there any readily available organic preservative that I could add to the sauce that would preserve the color, flavor and texture? Not only during shipping, but also in what I would like to put up for myself?
Update: It appears the consensus is to leave out the cheese, which is certainly doable. I am still holding out hope that some master of canning or food preservation has some advice on a preservative I might add. Especially if that preservative or process would allow it to remain shelf stable at room temperature.
Best Answer
I'm not totally certain whether you're trying to end up with room-temperature shelf-stable pesto. If so, you may have to look elsewhere. However, my family has grown bumper crops of basil before, and been left with the task of trying to preserve it for year-round pesto.
You noted that making pesto and freezing it doesn't work well due to the Parmesan cheese component. We would get around this by making a mix of the chopped/blended basil and olive oil, and freezing that combination. With that, you may also be able to add your salt & garlic as well, though I've not personally tried that, nor with including the pine nuts in the frozen package.
This does require the recipient to make additions on their end, but it does preserve the basil well. We would keep ziplocs of the basil-oil slurry in the freezer, and then done the end steps of adding the pine nuts/Parmesan/garlic and such.
I think that's fairly similar to what the answer in the question you linked does, but I can confirm that it preserves well and the mixture stays a dark green, not brown. If you're pretty sure that the packages are going to stay at freezer temperatures, I'd be confident in it working well. I'm not sure at what temperature you'd start having issues, as that's not something that we experimented with.