09 October 2012

Canning winter squash the USDA way

I've been a little horrified by some of the YouTube videos and blog entries posted by home canners and "preppers" who I'm sure are very well-meaning, skilled, and as yet not dead from botulism. I'm no nutrition expert; my kitchen sure isn't a food laboratory; and really, Jim, I'm a lawyer, not a microbiologist -- so what do I know about safe home canning practices?

As it turns out, I do know a lot about home canning. I've been canning for at least 15 years. But since I'm not a microbiologist, and since my kitchen isn't food laboratory, and since I'm not a nutrition expert, I rely on other experts to put home canning practices and recipes through scientific testing under controlled laboratory conditions. I'm thrilled that the USDA and various land-grant university extension services do that work for me, and I'm happy to use their results.

Last week I discussed that a home canning blogger offered a good looking but problematic guide to putting up winter squash. This vegetable is particularly tricky to can at home because its water content and texture can vary so much. In order to make sure the home canning process thoroughly kills the bacterial spores that produce the deadly botulinum toxin in this uneven vegetable, you're supposed to make sure that you: (1) pack the jars with heated one-inch cubes of squash, never purée; and (2) process the jars in a pressure canner, pints for 55 minutes and quarts for 90 minutes.

I don't know why some of these Internet home canners don't follow these two rules. (At the link above, for example, they canned purée and processed the quart jars for under 90 minutes.) If the issue is that they prefer purée to cubes, home-canned cubes are simple enough to mash or purée when the jar is opened. If it's an issue of processing time, well, I think there's little difference between 75, 80, or the USDA-recommended 90 minutes. An extra 15 minutes of stove fuel will do very little harm to my utility budget, but an under-processed jar of food can make my household very ill.

You know what else I see on some of these Internet home canners' websites and videos? Messy kitchens. Messy both in clutter and in dirt. Again, I don't have a sterile laboratory of a kitchen myself. But I clear off my workspaces, lay out all my tools ahead of time in an almost complete mise en place, and clean my utensils and dispose of waste as I go with a canning project. And I keep my fingernails short. Who are these people with manicures? Do they really want that acrylic, varnish, and adhesive getting into the jars? Ew.

But on to the Rowhouse Livin' project. We canned six average sized butternut squash. As always, if you are not familiar with home canning, please see the National Center for Home Food Preservation. This blog entry does not substitute for a complete set of instructionson safe home canning practices. A full guide for canning is especially important where, as here, we're talking pressure canning. This food item CANNOT be safely canned in a boiling water bath canner. More!

First, I've peeled the squash and chopped it coarsely. Note how I started with a clean, clear counter and sink, and I'm cleaning up as I go: peels and seeds go down the sink disposal after I've dealt with a couple of squashes. This is because after I'm done using the stockpot, I would like to have an empty sink to put it into, not a sink clogged with six squashes' worth of peels and seeds.

One-third of the way there, and the pot is almost full!
Next, I've chopped the squash into one-inch dice and have thoroughly heated it through, boiling it for a few minutes. This makes the squash expand to its largest possible size before it goes into the jars, and it forces air out of the tiny, tiny air pockets in the squash. (Don't believe me? Oh, it's there, and it's why squash floats.) If you skip this step and try to raw- or cold-pack your squash, your jars will overflow in the canner and you'll have wasted time, food, cooking fuel, and money.

Slotted spoon added for scale. Can you tell the difference
between this and diced yellow peaches? Neither can I,
which is why I'm careful to label my jars
Now gently pack the diced squash into heated jars. You'll want about this much squash, but you need to top it off with cooking liquid:

Gentle, loose pack. You don't want to compress or, um,
squash the squash

Here, I've topped off a jar with some liquid, leaving one inch of "headspace" at the top of the jar. That means there is about an inch of space between the top of the food and the rim of the jar:

But it still can't go into the canner yet! You need to take a utensil and poke around the jar to release any air trapped in pockets around the food, and then maybe add some more cooking liquid to bring it back up to that one-inch headspace. The utensil should be plastic, not metal, because metal can scratch the inside of the jar, weakening the glass and putting you at risk of a jar failure in the canner. Here, I've used the handle end of a melamine pasta fork, because I'm too cheap to buy a special tool dedicated only to removing air bubbles:

Again, gently and carefully to preserve Dice Integrity,
which I'm claiming right here and now as my band name
Now I wipe the top rim of the jar, place a pre-heated lid on it, secure it with a screw band, and place the jar in the canner. Repeat until all the squash pieces are used up.

With this batch, I couldn't fit all of the squash into the stockpot at once. So I cooked up as much as the pot could hold, filling almost five quart jars. I let the jars sit in the canner while I heated the rest of the squash. When it was ready, I topped off that fifth jar and then completely filled a sixth. The seventh jar -- it would have been a maximum canner load -- didn't completely fill. I could have added hot water to it and processed it anyway, but instead I decided to save a lid and put that jar in the fridge for use later this week.

To continue. Follow your canner manufacturer's instructions for bringing it up to pressure, and then keep it at 10 pounds of pressure for 90 minutes. When time is up, cool the canner per the manufacturer's instructions and remove the jars for cooling, 12 to 24 hours:

Six squash yielded six-plus quarts of dice
After they have sat overnight, remove the bands and wipe down the jars for storing in the pantry. But pre-final step: clean the canner, dry it completely, and put it away. When I get up tomorrow morning to put those jars away, there will be no other clue in my kitchen that I had a canning project going on today.

And that is how Rowhouse Livin' cans winter squash the USDA way.


Tom Cloyd said...

Very nice demo of the right way to do it. I'm about to do my very first batch of winter squash, and your images give me a much clearer idea of where this little project is going. You explanation about the reason for boiling the squash cubes before canning is quite nice - have never had that explained anywhere else. Thanks for all the help!

Michele Grant said...

Tom, it was my pleasure! I'm glad you found the demo useful.

Jacquie MacDonald said...

The seeds are edible! I roast mine after soakng them in a salty solution (amount varies) with granulated garlic. For a sweeter taste, try tossing them with some sugar and cinnamon! Anything's possible! These seeds are rich in Omega3. Roast them in the oven on a cookie sheet under the broiler, but watch carefully or they will burn. I roast mine in around 5+ minutes, the time varies...

Michele Grant said...

Thanks for the tip!