Tag Archives | canning 101

Canning 101: How to Shuck Corn Easily

shucked corn

Two years ago, I made a triple batch of roasted corn salsa (the recipe is in Food in Jars). It is my husband’s favorite preserve and I like it a whole heck of a lot as well. We eat it with rice and black bean bowls in the winter, and over chicken fajita salads once the weather starts to warm. It’s also a nice topper for homemade nachos (as you can see here).

As much as I enjoy eating this salsa, I’ve never enjoyed the process of making it. That’s all changed now that I’ve discovered the secret to easily shuck the corn and remove most of the corn silk. I now roast the corn at 400 degrees F in its husk for about seven minutes in a hot oven before attempting to shuck it. Once the time in the oven is up, I pull the corn out and let it cool for ten minutes or so.

oven roasted corn

Once it is cool enough to handle, the husk comes off cleanly and leaves only a strand or two of corn silk behind (and those strands are easy enough to wipe away). This little trick has transformed a job I dread into one where I can clean two dozen ears of corn in just a few minutes without feeling in any way irritated by the task.

I do have a word of warning about this trick. Corn husks are flammable. Make sure to keep the husks and silk well away from the flame or heating element. I like to stack the ears on a rimmed cookie sheet so that I can move them quickly if something starts to singe. I also take care not to stray far from the kitchen when I’m roasting corn like this so that I can keep a close eye on the happenings.

PS: If you have an outdoor grill, I bet you could use that instead of your oven. I don’t have access to a grill, so stick to the oven approach.

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Canning 101: Can You Safely Can on a Glass Top Stove?

Andrea's stove

Obviously, this is not a flat top stove. I didn’t have a picture a picture of one, so this is standing in.

In the last two days, I’ve gotten three different questions about canning on glass top stoves. And so, I figured it was high time that I added a blog post to the Canning 101 archive to explain why it’s not recommended and how you can potentially work around those warnings. Read on for more!

If you are the owner or regular user of a glass top stove, you may have heard that you’re not supposed to do any canning on your smooth, easy-to-clean stovetop. For long time canners who find themselves with these stoves, this news can be quite a blow.

There are three primary reasons why manufacturers recommend against canning on a glass top stove. The first is that many older canners have concave bottoms. When you combine a concave bottom with a flat surface, heat, and water, there is a risk that a seal will form between the canner and the stovetop. It’s not a huge deal until you go to move a canner that has suctioned itself to the stove. The seal can be strong enough that attempting to move the canner can result in a cracked or shattered stove top (this can also happen if you put a lid on your flat surface).

The second reason that it’s not recommended is that a full canner load of seven quart jars can be heavier that the stove top can bear. Even if your pot has a flat bottom, if it ends up weighing more that the glass surface can bear, you can still end up with a broken range.

The third reason is that some glass top stoves cycle the heat on and off, and so aren’t able to hold a steady boil. If you can’t hold a canner at a constant boil, you cannot guarantee that you’re getting the full level of heat penetration necessary for your preserves to be sterilized and safely shelf stable.

Happily, not all is lost for potential canners with flat glass top stoves. You can eliminate the risk of breakage through suction by using a pot with a flat bottom. A light-weight stainless steel stock pot (like this one) works well as a canning pot and will never seal itself to your stove. It also has the added benefit of being light enough to prevent the surface from cracking or breaking due to too much weight.

There is the issue of maintaining a rolling boil. Some stoves can do it and others can’t. Test your stove by bringing a pot of water to a boil and tracking the temperature with a candy thermometer while it boils. Does it stay at or near to 212 degrees F? Or does the temperature fluctuate a great deal? If you can maintain a rolling boil, you should be good to go.

And, if all else fails, get yourself an induction burner and an induction capable pot and run that as your processing station. Where there is a canning will, there is always a way.

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Canning 101: The Easiest Way to Peel Tomatoes (Peaches Too!)

tomatoes in a bowl

Let’s talk about my favorite way to quickly peel tomatoes and peaches. I mention this technique a lot when I teach classes, and even wrote about it in this post in the context of peeling peaches, but as I broke down a few pounds of tomatoes today, thought it might just bear repeating.

tomatoes in a pan

Instead of bringing a big pot of water to a boil in order to blanch and peel tomatoes before turning them into a preserve, when I have a relatively small batch to peel, I do this. I trim away any soft spots, remove the cores from the tomatoes and cut them in half. Then, I arrange them cut side down in a heat proof baking dish.

tea kettle

While I’m prepping the tomatoes, I fill up my trusty tea kettle and bring it to a boil.

pouring water

When the water comes to a boil, I pour it over the tomatoes. You don’t need to fully submerge them, but you do want enough water in the pan so that it doesn’t cool down too quickly.

pan over tomatoes

Then, I slap a cookie sheet over the tomatoes to trap the heat and leave the whole thing alone for 10 or 15 minute, until the tomatoes have cooled down enough to handle.

peeled tomatoes

Drain the tomatoes and peel. The skins should slide right off and leave you with perfectly peeled tomatoes, ready to be turned into salsa or cooked down into a small batch of pizza sauce (that recipe is in Preserving by the Pint!).

peeling tomatoes

Of course, this technique really only works for smallish batches. If you’re prepping ten or more pounds of tomatoes sauce, heating up the big old blanching pot is still going to be your best bet.

What tricks do you guys have for easily prepping summer fruit for canning?

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Canning 101: How to Use a Thermometer to Achieve Set

three thermometers

We are currently smack dab in the middle of marmalade season. Though citrus is available all year round, it is both at its peak and most affordable during January, February, and March. Because of this, I’ve been getting a number of questions about marmalade making, in particular, the art of using a thermometer to determine when a batch of marmalade has reached its set point.

The reason this comes up more during marmalade season than other times of the year is that citrus is naturally high in pectin and so many marmalades can be made without the addition of any commercial pectin. The trick then becomes cooking the fruit and sugar combination to around 220 or 221 degrees F, which is known as sugar’s gel point.

When the sugar reaches that gel point, it undergoes a physical transformation and thickens. That increased thickness gives it the ability to bond with the natural pectin in the citrus and create a thick, spreadable marmalade.

thermometer probes

The issue that people are having is that they are finding a mismatch between the temperature that their thermometer is displaying and the consistency of the cooking marmalade. Typically, the marmalade appears far more cooked than the temperature on the thermometer read-out would indicate. The result is a burnt, overset preserve that is deeply frustrating, given how much work is involved in prepping a batch of marm.

There are two reasons that this can occur. One is that the thermometer is giving a faulty reading. The way you can test to determine whether your thermometer is reading accurately is to bring a saucepan of water to a boil. Once it starts rolling, insert the thermometer into the water. If you’re at sea level, it should read 212 degrees F. If you’re at higher elevations, that rolling boil will be achieved at lower temperatures. If the reading is wildly different from that which your elevation would indicate, get yourself a new thermometer.

thermometer probes with notes

The other reason that your thermometer might not be reading accurately is that is may not be be sufficiently covered with the cooking preserve. Every thermometer has a mark indicating how much the probe must be submerged in order to give a true reading. As you can see in the picture above, the three thermometers in my kitchen all need to be submerged to different depths in order to perform accurately.

If you’re making a small batch of marmalade, you sometimes run into a situation where there’s just not enough volume in the pot to fully submerge a traditional candy or deep frying thermometer (I often run into that problem with the left and center thermometers). In my case, I deal with that situation by using the Thermapen on the right or by using other methods to check my set.

Try the plate/saucer test or if it’s a truly small batch, use your eyes and ears. As it reaches the set point, marmalade will simmer more vigorously. As you stir, watch to see if it is leaving an open space for a moment after you pull your spoon through. That’s a sign of thickening as well.

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An Update on the Canning 101/New to Canning Plan

spices

Several weeks back, I wrote a post asking for feedback about my Canning 101 and New To Canning categories. It’s taken me a little bit of time to digest all the questions and figure out how to tackle them. I found that they shake out into about ten categories (though one is something of a catchall). Here’s what I’m finding that you’re interested in:

  • Canning Basics
  • Fruit Preserves
  • Pickles
  • Tomatoes
  • Sugar
  • Altitude Adjustments
  • Recipe Sourcing and Development
  • Pressure Canning
  • Using Preserves
  • Other Questions

What I’ve done is tried to pull out all the individual questions. Though I have answered many of these questions in one way or another, often those responses are buried in the middle of another post and so aren’t always easy to find. So here’s the plan. Starting next week, I’m going to start answering these questions. I probably will jump around the list a lot and will occasionally group two or three questions together if I think they are different sides of the same coin.

Some of these posts will be short and will live forever under the Canning 101 header. Others will be longer, tutorial-style posts and will get filed under the New to Canning. Hopefully, they’ll all be both useful and interesting. I’m going to use the list below as something of an index, so I will link the questions to the answers once they’re written and I may add to the list as I work.

Finally, if you have a question and don’t see it here, leave a comment and I’ll add it to the list!

Continue Reading →

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Canning 101: Understanding Acid and pH in Boiling Water Bath Canning

pickles on a table

Today’s post is inspired by a rash of questions I’ve gotten recently in regard to my recipe for Honey-Sweetened Peach Vanilla Jam. A number of you are concerned because while that recipe contents lemon zest, it doesn’t contain any lemon juice. That jam is safe as written, but we need to dig a little deeper into canning science to understand why. Read on! 

If you’ve been canning for any length of time, you’ve probably heard mention of acid levels in relation to safe boiling water bath canning. Anything that is preserved in a boiling water bath must have a high acid content. The reason that high acid levels are important is that the presence of acid inhibits the germination of botulism spores into the botulism toxin. Botulism spores can only develop into the botulism toxin in low acid, oxygen-free environments.

When you preserve something in a boiling water bath canner, you heat the jars and their contents to the boiling point (that temperature varies depending on your elevation, but at sea level the boiling point is 212 degrees F). That heat is enough to kill off the micro-organisms that can cause spoilage, mold, or fermentation, but it’s not enough to kill botulism spores (they require far higher temperatures). The process of boiling the jars also helps to drive the oxygen out of the jars, creating a vacuum seal. For jars that have sufficient acid content, the result is a jar of food that is safely preserved and shelf stable.

The way food scientists (and home canners) determine whether something is high or low in acid is by pH. If something has a pH of 4.6 or below, it is deemed high in acid and is safe for boiling water bath canning. If the pH is 4.7 or above, it is considered low in acid. We’ll talk more about how to preserve those foods that are low in acid and have a pH of 4.7 or above another day, but to give you just a hint, that’s often where a pressure canner comes in.

If a food is close to the 4.6 pH point, you can often add enough acid to bring that product into the necessary safe zone. Fruits like tomatoes, figs, asian pears, melons, persimmons, papaya, white peaches and white nectarines, and bananas are often just a bit too low in acid in their natural state for safe canning. So in order to lower the pH to a safe level, we add either bottled lemon or lime juice, or powdered citric acid to products featuring those ingredients. Once the acid levels are high enough to inhibit the botulism spore’s ability to germinate into a deadly toxin, that product is safe for boiling water bath canning.

However, there are a world of foods out that naturally have a pH that is well within the zone for safe preservation in a boiling water bath canner. Here’s where we come around to the peach jam I mentioned in the introduction to this post. That recipe specifically calls for yellow peaches, which typically have a pH of 3.4 to 3.6. I know the general pH range for yellow peaches because the FDA provides a handy reference page on their website that lists the general pH range of most common fruits and vegetables.

You could certainly add lemon juice to my jam in order to balance the flavor and add a little extra pectin (citrus fruit is naturally high in pectin), but it’s not necessary for safety.

Updated to add: One last thing! It’s important to remember the pH of the entire jar counts here. This is why it’s so vital to follow tested, reliable recipes for things like tomato sauce or salsa. Sure, you can add bottled lemon juice to your tomatoes to lower the pH, but if you’ve also added onions, garlic, and basil to your sauce, you’re not just balancing the acid of the tomatoes, you’re also taking the rest of the ingredients into account. That’s why salsa recipes designed for canning contain so much bottled lemon or lime juice, or vinegar.

 

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