Tuesday, November 30, 2010

Canning, aka Stress Relief: part 2

There I am, stressed out about work and fresh from a visit to my friends' farm in the Capay Valley (my number one stress reliever). As always, I was sent back with a dozen eggs from their hens and bags full of what they had growing. Which this time was kadota figs, several varieties of eggplant, and peppers. Red peppers, yellow peppers, green, fat, skinny, bulbous peppers. Peppers the size of my pinky nail in nail polish colors. Purple-streaked green peppers. Orange peppers the color of the sunrise.

So I went nuts. Two kinds of fig jam: Fig with Vanilla and Fig with Honey and Bay (both Christine Ferber, natch). Caponata with the eggplants. A savory hot sauce with the red chiles. Spicy, spicy green chile-and-vinegar sauce. And just because I was on a roll, I picked up a case each of tomatillos and pasilla chiles from Berkeley Bowl for tomatillo sauce.

Here is the recipe I used, adapted from Well-Preserved: Recipes and Techniques for Putting Up Small Batches of Seasonal Food by Eugenia Bone:
(I scaled up x16 to get through my 40lb case of tomatillos)

Tomatillo Sauce
2.5 lbs tomatillos, husked and rinsed
2 poblano chiles
1 jalapeno chile
2 cups chopped onion
3 chopped garlic cloves
.5 cup lemon juice
2 teaspoons salt
Bring a pot of water to a boil and blanch the tomatillos just until they begin to soften, about 30 seconds. Puree them in a blender or food processor.
Roast the chiles either under a broiler or over a gas flame, turning to char them evenly. Let cool, then peel off the skins. Don't rinse as you will lose some of the roasted flavor. Remove and discard the seeds and pith, and chop flesh finely.

Combine everything in a pot and bring to a boil. Reduce to a simmer and cook for about 20 minutes.

Ladle into pint jars and seal with new lids. Rims can be reused. Process in a boiling-water bath for 15 minutes. Turn off the heat and let jars sit in the hot water for 5 more minutes before removing. (This prevents breakage.) Let cool.

Now for the technical details:

This recipe has a lot of lemon juice in it. Too much for my taste, really. This is because, for a product to be safe for canning it must have a ph of 4.5 or lower. (Ph is a measure of acidity. Remember high school science class? I didn't either, until I started bottling syrups for a living.) Botulinum toxin thrives in a low-acid, oxygen-free environment. Canning cookbook authors are extremely worried that someone will make their recipe and end up poisoning their loved ones because the recipes wasn't followed to the letter. So they tend to vastly overcompensate with the acid level in their recipes: if your vegetables are larger than normal, the product will still be safe. When these authors test recipes for safety, they typically send samples to a lab. The lab purees the samples and tests the ph. So, because I have a ph meter, I did the same and realized I didn't need nearly as much lemon juice as the recipe called for.

Now, I'm not suggesting you go around reducing acid from canning recipes willy-nilly. Not at all. I'm just saying that there is a reason the recipes are structured the way they are, and that reason has nothing to do with taste. If you really like canning, and you want to expand beyond jam (fruit is naturally acidic and rarely needs additional acidifiers), I suggest picking up a ph meter. Make sure it's food-safe, and a temperature compensation feature saves a lot of time.

The other detail, and you will never see this in any canning cookbook, is that whole boiling water bath process? Unnecessary. Seriously. What is necessary is that the entire finished container, the contents plus jar or bottle, must be at a sufficient temperature when it is sealed. You can heat the jars in the oven, or boiling water if you like (although this is not always necessary), and keep your mixture at a simmer. Fill, wipe down the threads of the jar, apply a new lid, and screw on the bands. Do this reasonably quickly. If you have a European grandmother perhaps she does this then turns each jar upside down until it cools. (I don't; I've just heard stories. Sigh.) I am not sure of the science behind this, but I do like the idea that there is moisture contacting the entire soft gasket on the inside of the lid, so if the seal doesn't form you can see some of the sauce squeezing out. The high temperature forces the oxygen out, and as each jar cools it makes that satisfying ping! noise as the lid gets suctioned down.

The reasons for the boiling-water bath are safety and liability. If your mixture is not hot enough, it won't create the necessary seal. You can fill at any temperature as long as you hot-water-bath process your jars. As for me, I water-process anything chunky and do a simple hot fill with sauces. Mind you, I enjoy canning to relax, not to add to my stress.

No one wants people to get sick from their recipes. Also, no one wants to get sued. So precautions abound, and often the recipes suffer as a result. Just like other cookbooks, not all canning recipes make for yummy food. If you ensure that you are doing it safely, make the changes you like. And enjoy the bounty!

1 comment:

parviziyi said...

I've liked reading this blog, thank you.

"What is necessary is that the entire finished container, the contents plus jar or bottle, must be at a sufficient temperature when it is sealed." Right. One of the contents in the jar before you put the lid on is the air at the top of the jar. The air may very well not be at the sufficently high temperature even if the liquid and the jar are very hot. If you turn the jar upside down after sealing it, you cause the air to flow up through the hot liquid, which brings the air to a higher temperature, which kills the bacteria in the air.