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Canning 101: How to Prevent Jam Separation

fruit float image

This time of year, lots of people are making and canning strawberry jam. Though it’s a universally loved preserve, I find it to be one of the trickier jams to get right, particularly for beginning jam makers. One of the reasons that people struggle with strawberries is that the finished jam has the tendency to separate into two layers* once it has cooled in the jars.

If you are one of the ones who have struggled with this two layer jam, worry not. It’s not a sign of danger or even that you did something wrong. It’s simply a sign that there is still some air trapped in the strawberries. They are lighter than the syrup and so rise to the tops of the jars.

I find that this jam separation happens primary in recipes that call for relatively short cooking times or very large pieces of fruit that have not been given a long maceration period.

You can work to prevent this two layer effect by chopping the fruit into smaller pieces, macerating it with the sugar overnight, mashing it with a potato masher during cooking (this action is best if you’re noticing big hunks of fruit bobbing around towards the end of cooking), and even extending the cooking period a bit.

If you’ve taken these actions and you’re still noticing that your jam is separating during the cooling stage, you can gently shake the cooling jars to reintegrate the fruit and the syrup.

My preferred method of dealing with this separation is simply to tell people that I meant it to be that way and that if you want a more integrated preserve, that they should stir the fruit into the now-set jelly when they open the jars.

*This can also happen with other varieties of fruit as well, but is simply most common with strawberries.

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Canning 101: White Vinegar in the Canning Pot Prevents Mineral and Metallic Deposits

white vinegar

I was reading through the comments on the FreshTECH Electric Canner a moment ago and saw several people mentioning their frustration with their current canners because they left spots and rough deposits on the jars. Happily, there is a way to prevent this without investing in a new canner. Pour about 1/2 cup white vinegar into your canning pot when you first set it up.

Whether the residue on the jars is minerals from hard water or particulate matter from your canning rack, adding vinegar to the water will help keep it off the jars and prevent build-up on the inside of your canner. Make it part of your canning routine this summer!

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Canning 101: Can You Preserve With Artificial Sweeteners?


A couple weeks ago, I wrote a Canning 101 post about the different roles that sugar plays in preserving. This was my attempt to conclusively answer the questions I regularly get from people wanting to reduce the amount of sugar in their preserves.

There was one thing I didn’t address in that post and that was question of artificial sweeteners, like Splenda, Equal, Truvia, or xylitol. Personally, I don’t work with artificial sweeteners much simply because I don’t like the way they taste. I do understand, though, that for some folks it is necessary to use these products as a way to cut back on sugar. So here we go.

First, let’s talk about the situations in which artificial sweeteners aren’t going to work. When you make jam in the traditional manner, you are relying on the fact that as you cook, the sugar you added to the fruit is going to thicken as heat is applied, eventually thickening to the point where it bonds with the conventional pectin (either natural or added). If you remove the sugar from the equation, the jam is never going to set.

Sure, you might be able to boil it down into something to stir into yogurt, but it’s not going to be jam. What’s more, lots of the artificial sweeteners become bitter during extended cooking, so if you added your sweetener at the beginning of the cooking and then boiled the heck out of the fruit for 45 minutes, the finished product may well be inedible.

What this really means is that you can’t take a traditional recipe for jam, swap in Splenda and think you’re going to get anywhere near the same result. I know this might feel frustrating to some of you, but truly, this advice will save you buckets of aggravation in the long run.

So, here’s what you can do. You can use pectin that was designed to work in low or no-sugar environments. There are a couple different versions out there. Ball makes a special modified pectin and the package insert will be able to guide you through the process of creating serviceable jams.

Pomona’s Pectin is another good option. Known as low methoxyl pectin, it’s requires both a pectin made from citrus peels and a calcium solution. Instead of needing sugar to trigger the set, the calcium activates the pectin. This means that you can make spreadable preserves with whatever sweetener you choose, including a wide range of artificial sweeteners.

Another option is to start making fruit butters rather than jams and jellies. When you make a fruit butter, you cook a fruit puree at low temperature for a long period of time. In doing so, you remove much of the moisture, and concentrate the natural sugars in the fruit. You can then either leave it as-is (though the juice of a lemon or two will help preserve the color and brighten the flavor) or adjust it slightly with the artificial sweetener of your choice.

Just remember, as discussed in this blog post, when you reduce or remove sugar, shelf life and the quality once open shortens. I combat this by making low sugar or sugar-free preserves in small batches and canning them in four ounce jars, to ensure that they are as good and fresh as I can make them.

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Canning 101: Why Do Colors Change in Home Canned Foods?

Packing jars

It happens to all of us at some point in our canning careers. You go to retrieve a jar of precious, brightly colored jam, only to discover that the once vibrant color has gone muddy and dull. Once you get over the disappointment, you start to wonder two things. What happened to cause the loss in color and is that jar of jam (or pickles, jelly, fruit butter, relish, fruit halves or tomatoes) still safe to eat?

There are a number of reasons why a preserve has lost its color. Let’s dig in.

Weather Conditions During Growing – The opportunity for discoloration starts while the fruit is still on the tree. Fruit that’s grown during really hot, dry summers has a tendency to turn pink once in the jars. If you experience this kind of discoloration, worry not. While it can’t be avoided, it won’t impact the flavor, texture or safety.

Picking and Storage – Produce starts to break down as soon as it comes off the tree, plant or bush. Heat and extended storage can lead to faded color. However, as long as the fruits and vegetables were still in edible shape when it went into the jar, the product is still safe to eat.

Oxidation – This one is the bane of all canners. As soon as you start cutting up fruit and exposing the flesh to air, it starts to brown. During prep, you can stave off oxidation by submerging the fruit in acidified water (a couple tablespoons of bottled lemon juice in a bowl will do the job). But even when you think you’ve done everything right, you sometimes have some browning on the surface of the finished jam (peach, nectarine, and apricot are particularly prone to this) or, in the case of whole fruit, anything peeking up out of the syrup may discolor. Still safe, though some people prefer to scrape the browned layer away.

Light Exposure – Anytime something with color is exposed to ultraviolet light, it will fade. The reason is that those UV rays weaken the chemical bonds of the color particles over time, causing them to break down. We experience this as color loss. Light-faded products are still safe to eat, but they may not be as delicious as they originally were.

Reduced Sugar – Sugar helps maintain color because it absorbs water and acts as a buffer. The more you reduce sugar in a preserve, the more prone to color loss that product will be.

Exposure to Reactive Metals – Reactive metals like copper, aluminum, and cast iron can leach small amounts of metal into your preserve during cooking, which can lead to darkening and a bonus metallic flavor (yum!). It’s best to keep highly acidic foods out of cookware made with these metals (the exception is high sugar preserves cooked in copper. The sugar prevents the metallic leaching). These preserves aren’t unsafe, but they don’t always taste good.

Use of Salt with Additives – This applies primarily to pickles, but it’s a good one to know. The reason recipes typically call for pickling salt is not just because it dissolves quickly. It’s also free of iodine and anti-caking agents, both of which can cause pickles to yellow or darken.

The basic takeaway here is that most forms of mild fading or browning don’t impact the safety of your finished product. As long as the seal is good, the preserve don’t have any mold growing on the sugar, and it doesn’t bubble when you open the jar, it’s really okay (just to be clear, we’re talking about high acid preserves here). For best quality, keep your canned goods out of direct light and in a place between 50 and 70 degrees F.

Information for this post came from the following sources: Bernardin FAQ, NCHFP Pickle Problems page, Fresh Preserving, the Library of Congress and my brain.

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Canning 101: Can I Reduce the Sugar?

3 cups sugar

Like so many of these Canning 101 posts, I’m writing this one to address one of the questions I am frequently asked. I’ve covered this topic as part of larger blog posts before, so if you’re a long-time reader, some of this may be familiar. But it felt like time to pull out this question specifically in the hopes of helping people find the information more easily.

So often, people look at one of my recipes and see the volume of sugar it calls for and have something of a heart attack thinking about all those cups. And so, they write in to ask, “can I safely reduce the amount of sugar in this recipe?”

The answer is that you can always safely reduce the amount of sugar in a recipe, because sugar doesn’t make things safe. The only thing that makes a jam, jelly or other sweet preserve safe for canning in a boiling water bath canner is the acid content, because that’s what prevents any potential botulism growth.

However, when you reduce the amount of sugar in a recipe, you can compromise that preserve’s shelf life, yield, and ability to set up.

Sugar is a powerful preservative, because once you have a certain concentration of sugar in a recipe, the sugar sucks up all the available water. Mold and bacteria need water in order to develop, and if there’s no water available, they cannot grow.

This is why preserves with higher amounts of sugar hold their quality longer than lower sugar preserves. As long as you’re okay with a somewhat decreased shelf life and a relatively short lifespan once the jar has been opened, then go ahead and reduce the sugar.

Things get a little trickier when you take set into account. Sugar has the ability to change physical consistency as you heat it. If you’ve ever made candy, you’ve seen how you get different outcomes the higher you allow the temperature of the cooking sugar to go.

When you make a sweet preserve, you boil the fruit and sugar together, cooking out the water and increasing the concentration of sugars (both natural and added) to the point where they can elevate in temperature to around 220 degrees F. That’s the point at which sugar starts to thicken into a gel and is then able to bond with the pectin (again, both the natural pectin in the fruit and any pectin you added) and that’s how your jams and jellies set up.

If you pull out a lot of the added sugar in a recipe that is depending on sugar to achieve set, the chances are good that the finished product may be forever runny (true story. As a kid, I thought all homemade jam was inherently runny, because my mom always reduced the sugar to the point where set could not be achieved).

You can often reduce the sugar a little bit, but if you do, you may need to cook it longer so that the proper concentration can be reached. That reduced sugar and longer cooking can end up reducing the yield by as much as a cup or two.

Now, if you’re working with Pomona’s Pectin or some other low/no sugar pectin, you can ignore everything I’ve said about set and yield, because those pectins use an entirely different paradigm in order to achieve set. But the advice about shelf life will still hold true.

One final word. Do not take this blog post to mean that I am advocating super high sugar preserves. My favorite ratio for basic jam is two parts fruit to one part sugar, which is actually a fairly conservative amount of sugar, when you look at the traditional jam recipe canon.

When I make smaller batches, I drop the sugar to a three parts fruit to one part sugar ratio, because smaller batches lend themselves to more rapid water evaporation and sugar concentration. And I’m currently writing a book about preserving with a half dozen natural sweeteners, so I am more than open to using a wide world of sweeteners. But I feel strongly that people understand why an ingredient is in place before they go and start changing things up.

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Canning 101: How Long do Home Canned Foods Really Last?

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You hear a lot of differing advice from people on the subject of how long it’s okay to keep your preserved food once you’ve canned it. Some people say that it’s a year to the date that it went into the jars. Others will tell you that they recently ate the last of the tomatoes their grandmother canned in the summer of ’99 (1999, that is). I’m here to tell you that it’s somewhere in between.

If you talk to one of the Master Food Preservers out there or folks from the National Center for Home Food Preservation, the answer goes something like this: “For highest quality, properly stored preserved foods are best eaten within a year of canning.” (Here’s exactly what the NCHFP says.)

Some people might read that statement and think that it means that they have exactly a year to eat through every last jar. The real answer is a bit more nuanced. You will get the very best flavor and quality from a jar that is in its first year, but there’s no internal self destruct devise inside the jar that goes off on day 366 or 367. Preserves older than a year are still safe for consumption.

Home preserved foods remain safe for eating far longer than their first year, but their quality does decline the longer the jars remain on the shelf (or in my case, under the couch). This means that the jam you made two or three years ago is probably still just fine to eat but it may not taste quite as good as did on that summer afternoon when you first put it in the jars. Chances are good, though, that it will still be more delicious than anything you’re able to buy at the grocery store.

If you have some elderly high acid preserves that you’d like to eat up but are making you nervous, here’s what to do. Pull one off the shelf and take a good look at it. In the case of jams, jellies, butters, and other spreads, look to see if it changed colors radically (a little surface discoloration is normal, but total color alternation or loss is suspect). For pickles, relishes, and whole preserved fruit, look at the quality of the brine or syrup. Has it gotten muddy or opaque? Has the liquid level dropped significantly?

If you don’t see any major change, open up the jar. Look at the surface. Has any mold or scum developed? Give it a good sniff. Does it smells funky, dirty, or boozy (do check to see if you added alcohol to the starting preserve, as then it won’t be a useful symptom of spoilage).

Once you’ve determined that all is well, give it a taste (for spreads that have darkened slightly on the surface, feel free to scrape away that top half inch). If you like how it tastes, dig in and include it in your rotation of open jars. Repeat these steps for each older jar you have in your stash.

Sometimes, long storage will rob a preserve of its flavor, particularly if it was sweetened lightly, or with honey or a sugar substitute. If it doesn’t taste like a whole lot, it may not be appropriate for spreading on toast, stirring into yogurt or serving with cheese, but you can always use up those less delicious jars in quick breads or as part of a braising liquid.

All that said, if you feel at all uncomfortable about something you canned, it is still always better to toss it than eat something that gives you pause. If you cringe every time you reach for a particular jar, it’s time to empty it out and move on.

Additionally, sometimes people try new recipes and then determine later on that they just don’t like them (not every recipe is for every person). If you made something and you just don’t like it, either give those jars away to someone who will appreciate it or dump the jars. There’s no reason to torture yourself with something you just don’t like.



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