Tag Archives | canning 101

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.

Comments { 7 }

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 →

Comments { 25 }

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.

 

Comments { 34 }

Canning 101: How to Substitute Pectin

pectin containers

During the time I was writing my first cookbook, I was something of a liquid pectin fan girl. I liked its ability to create a natural, not-too-firm set. However, as time has gone by, I’ve become more of an equal opportunity pectin user. I regularly use regular powdered pectin, Pomona’s Pectin, and even sometimes boost the set of my jams with some grated apple or ground lemon peel. I also make preserves without any additional pectin at all (thanks to the size of the batches, there’s not a drop of extra pectin at all in the next book).

I get a couple of pectin questions a lot. The first is, how do you choose the kind of pectin you use in each recipe? Unfortunately, I don’t have a really great answer for that one. I typically just reach for whatever’s closest in the kitchen. There’s no true formula. I do tend to use powdered pectin when I’m working with lower pectin fruits, but if there’s no powdered pectin around that day, I reach for the liquid. If I don’t have either kind of traditional pectin, I’ll use a splash of calcium water and a little bit of pectin from a box of Pomona’s Pectin.

The second thing I’m frequently asked is, how do you swap powdered pectin for liquid? Happily, I have a more concrete answer for this one. You use two tablespoons of powdered regular pectin for every packet of liquid pectin. The difference in usage is that instead of adding the pectin at the end of cooking like you do with liquid, you whisk the powdered pectin into the sugar before you combine it with the fruit. It responds better when you cook it the entire time and you avoid the risk of pectin clumping that can appear if you try and add powdered pectin at the end of cooking.

I’ve not come up yet with a perfect formula for converting full sugar recipes to lower sugar ones that use Pomona’s Pectin. The only tip I have about that pectin is that I always use about half as much as the recipes in the packet call for. I find that if you follow their instructions, you end up with a VERY firmly set jam. As someone who prefers a softer set, I find that using half as much gives me a satisfying outcome.

Comments { 41 }

New to Canning? Start Here: Boiling Water Bath Canning

stock pot and trivet

For years, there has been a something missing from this site and that was a post that detailed the basics of boiling water bath canning. I didn’t do it in the very beginning and then, as time went on, I felt a little embarrassed about writing that kind of post so late in the game. Whenever people would ask me for it, I would refer them to other websites. However, I’m happy to finally be filling in that gap with this post here today.

pot with trivet inside

So, a little disclaimer to start out with. I’m going to detail my particular canning workflow. This might not be exactly how you do it in your kitchen and that’s okay. We all find ways to make it work with the tools, equipment and space that we have. In the end, the most important things are that you get your jars hot, that you fill them to the proper headspace, and that you process them for the amount of time prescribed by your recipe. There’s a good deal of flexibility in the rest of the details.

filled with jars

As I mentioned in the first post in this series, any pot can be your canning pot as long as it’s tall enough to hold a rack and your jars, and that it allows the jars to be fully submerged in the water. I like this one, but the best pot to use is the one already in your kitchen. Once you’ve picked out your pot, position a rack in the bottom. I have a silicone trivet pictured here, but any round rack, collection of old canning jar rings or a hand towel will work. Then put your jars in the pot.

filling with water

Then, fill up the jars and pot with water. I like to use the hottest tap water available, as it speeds up the boiling process a bit to start.

all filled up

It’s a little hard to see in this picture, but at this point, I only fill the pot enough to just barely cover the tallest jar I’m using. This should be more than enough water for the processing stage, because once you lower your filled jars in the pot, they will displace enough water to sufficiently cover the jars (sometimes, you need to remove a little water from the pot to prevent overflow. If this becomes necessary, use something heatproof, like a Pyrex measuring cup so that you don’t burn yourself).

white vinegar

It is always a good idea to pour a generous glug of white vinegar into your canning pot before you start heating it. This will prevent any minerals present in your water from depositing on your canning pot or jars. I don’t live in a place with particularly hard water, but I still do this because it keeps my pot in good shape and makes it easier to clean.

canning pot on stove

Now the pot is ready to go on the stove an come to a boil. I do all of this before I ever apply heat to my preserves. That way, the canning pot has a head start on my product and the jars will be nice and hot when I’m ready to use them.

lids

Here’s where my practice diverges a little from what the  canning books will tell you. Almost all instructions (even those printed in my cookbook), will instruct you to take out a small saucepan, place the lids in it, cover them with water and bring it to a very gentle simmer. While this is good in theory (you don’t want to over soften the sealing compound), I rarely do it in practice.

Instead, I watch my heating canning pot. When it reaches a boil, I turn it down to a simmer and drop my lids in. Everything stays nice and hot until I need to use it. The sealing compound gets to the perfect level of softness and I am a happy canner.

removing hot jars

When the product is ready to go into the jars, I slide the canning pot off the heat and pull out the jars with a handy jar lifter. Just a note: These jars are hot, but not sterilized, because I turn the heat down to a simmer as soon as the pot boils. This works because the filled jars get boiled for at least ten minutes (and often longer) during the processing step.

However, if your recipe calls for a processing time that is shorter than ten minutes, you either need to increase the processing time to ten minutes, or you need to actively boil your jars for at least ten minutes before filled, to ensure you have sterilized jars.

ready to fill

Now you fill up your jars.

filled jars

Before applying the lids and rings, wipe the rims with a damp paper towel (I use the hot water from the canning pot as my dampening water, as the heat helps remove any stubborn sticky spots). Then, center a lid on each jar and secure it with a ring. Don’t over tighten the rings, because there needs to be enough space for the oxygen in the jars to escape. The term for this level of tightening is called “finger tip tight” meaning that you only tighten as much as you can with the tips of your fingers. I always tell my canning students that you turn just until the ring meets resistance.

processing

Once all the jars have lids and rings, lower them into your canning pot. Make sure the jars are fully submerged and are covered with about an inch of water (you need that much to ensure that they won’t become exposed during boiling). Turn the burner to high. When the pot returns to a boil, set a a timer to the prescribed amount of processing time. You do want to maintain an active boil throughout the processing of the jars, but make sure you control your boil. If the pot is madly rolling, the chances that you will burn yourself increase. Turn it down a little, to minimize splashing and injury.

removing finished jars

When time is up, turn off the heat. If you have an electric stove that stays hot for a while, slide the pot off the burner. You don’t want the water to be rolling when you reach in with your jar lifter. Then, lift your jars out of the pot and place them on a folded kitchen towel to cool (if you have countertops made from marble, granite, stainless steel or some other surface that stays cool, the towel is really important so that you don’t shock your jars).

all done

Once the jars are out of the canner, leave them alone and let them cool. Hopefully, you’ll hear a symphony of popping and pinging lids. This is good, it means that the seals are being formed. However, don’t freak out if you don’t hear those noises. Jars sometimes seal slowly and quietly. Once the jars are cool enough to handle, remove the rings and test the seals by holding onto the edges of the lids and lifting up an inch or two. If the lids hold fast, the seals are good.

Sealed jars should be stored in a cool, dark place without the rings. If the jars are at all sticky after processing, make sure to wash them before you put them away. Any sticky residue can attracts ants and other pests, so make sure your jars are squeaky clean.

Comments { 78 }

Canning 101: Tall Jars for Asparagus, Green Beans, and More

pickled asparagus in different jar styles

Whenever I’m about to start a canning project, I spent a few moments thinking about what I’m making, to ensure that I grab the best jars to do the job. This means that when I can jams, jellies, and fruit butters, I reach for the half pint (or smaller!) jars, aware that it will take me awhile to move through a sweet preserve.

When I pickle vegetables or can whole fruit that have a tendency to float, I use a regular mouth jar, knowing that the jar’s shoulders will help keep the veg positioned under the level of the brine. I do  tomatoes in quart jars, since I’ve found that’s the most useful size in my day-to-day cooking. And I frequently reach for a pint & a half jar when making pasta sauce, as a pint is never quite enough and a quart is always too much.

pint & a half jars

And when it comes to pickling tall, skinny things like asparagus, green beans, and garlic scapes, I reach for lanky jars that will give me plenty of real estate for the vegetable’s full length. I’ve found that there are three readily available versions of the long, tall jar and so thought I’d do a little show and tell post, to make everyone aware of their options.

First is the Ball Pint and Half Jars. They are sold in boxes of nine, hold 24 ounces and are 6 3/4 inches tall. Like all traditional mason jars, the jars and rings are reusable, while the lids need to be replaced with each batch.

Depending on where you buy them, the price on these jars starts at around $9.99 for a box and tops out around $20. The best deal I’ve found online is through True Value. The jars cost $11.99 a box and if you select their free “ship to store” option, you don’t pay any shipping fees. The only hitch there is that you need to have a True Value store nearby.

Weck asparagus jars

The next option is 1/2 liter cylindrical jar from Weck. It holds a little more than a traditional pint jar, but instead of having that space in a short, squat jar, it’s been stretched out so that you get about 8 1/4 inches of canning real estate.

These jars are beautiful, feel substantial, and are endlessly reusable. According to the US directions, the seals need to be replaced each time they are used. However, European instructions say they can be reused until they start to crack or show signs of age.

The price for a box of six of these jars ranges from $18.25 (from weckjars.com) to $29.95 (that’s the regular Williams-Sonoma price. However, these jars are currently selling for $23.96, because they’ve got their canning stuff on sale). Shipping varies for jars bought through Weck Jars. Right now, shipping is including on Williams-Somona, but I don’t how long that will last.

16 ounce Paragon jars

Finally, we have the dark horse jar. It’s a 16 ounce Paragon jar. It is 6 3/4 inches tall and seals with a one-piece lug lid (make sure to get one with a button, so you easily tell that it has sealed).

Made in the US and sold through jar distributors like Fillmore Container, this is the style jar that commercial producers are using for their tall, skinny preserves. Home canners can reuse these jars, but do need to replace the lids with each new batch.

They cost $5.61 a dozen. However, the lids are sold individually and cost $.25 a piece, which adds $3 to the total. The shipping can also add up, particularly if you’re buying just a single box. In the end, a dozen of these jars with lids would cost around $22 to get to me in Philadelphia. If this is the style you want to go for, see if you have friends who’d like to go in on an order with you, as it can save you cash in the end.

five jars

There you have it! A round-up of tall, skinny jars! Which one will you choose for your next tall project?

Disclosure: Fillmore Container gave me a box of the Paragon jars for review purposes. They didn’t pay me to write this post and my thoughts and opinions remain entirely my own.
Comments { 28 }