Complete guide to making, canning berry preserves

  • By Jan Roberts-Dominguez, Columnist
  • Tuesday, August 7, 2012 4:14pm
  • Life

It was mid-July and berries were bountiful at the Corvallis farmers market. From gigantic loganberries and big fat Spartan blueberries to elegant little black raspberries and chi chi marionberries.

I was experiencing the blessing and the curse of seasonal produce. It’s just so darned seasonal. Swooping in and tantalizing, then faster than a falling star disappears from a summer sky, poof! Gone for another year. A delectable but fading glow on my mind’s palate.

Let it go, I chant. A wise mantra for anyone whose pulse quickens at the sight of empty canning jars sparkling in the morning sun, potential written all over them.

With more than three decades of preserving under my belt, I can count on one hand the seasons in which I actually got through my entire preseason hit list.

But berries always make the cut. Especially caneberries. For the uninitiated, caneberries are, quite simply, berries that grow on a cane. They fall into two basic categories: raspberries or blackberries, and if you can get a look at their innards, it’s easy to tell the difference. Blackberries come with their center core still attached. If the berry has a hollow center, indicating that the core was left behind on the vine, it’s a raspberry.

Then there are the hybrids, which are berries resulting from the crosses made between the raspberry and blackberry. Those include the beloved and wildly popular marionberry, which was introduced in 1956 after years of cross-breeding.

Some of the earlier crosses produced the boysenberry, loganberry, Chehalem and Olallie. Berries of one sort or another will stay around through August. And then there are always the wild blackberries that are free for the picking.

So just relax. If you want to capture a bit of berry essence for down the road, read on.

Even if you’ve never tackled preserves before, stay with me. Just about every summer, I like to provide step-by-step guidelines for the traditional style of jam-making to help those of you just learning to preserve. Give them a once-over while you’re not in the throes of sticky fruit and sugar, then refer back to them as you go along.

Making jam the old fashioned way, step-by-step

Special equipment: canning jars and two-pieced lids; wide-mouthed funnel (for filling jars with jam without making a mess); magnetic jar wand (to remove the two-pieced metal lids from boiling-hot water); jar lifter (safely lifts jars into and out of a boiling water canner).

1. If you’re going to make your jams “shelf stable,” as opposed to storing them in the refrigerator, you will need to process the filled-and-closed jars in a boiling water canner. (Note: You’ll find such a pot in the same place where you’re obtaining all the other canning equipment.)

This is the time to fill the canner with water and get it heating up on a back burner while you make the jam. I’ll walk you through the “processing your jars in a boiling water canner,” in step 9.

2. Start with freshly washed canning jars and two-piece canning lids (available this time of year in most supermarkets and hardware stores). Wash them by hand in hot, soapy water, then give them a rinse and place the jars, bottoms up, on a towel-lined cookie sheet in a warm oven until needed.

3. To prepare the lids, just follow the manufacturers directions that came with them. Typically, you’ll place them in a pot of water that you’ll bring just to a boil then remove from the heat. The hot water softens up the sealing compound that is on the flat lids. Leave the lids in the hot water until you use them.

4. Get all of your ingredients prepared and measured.

5. Just start following the directions in the recipe for preparing your preserves. Recipes that come with packages of pectin are usually straightforward. Just make sure you handle each of the ingredients exactly as directed. Steps vary slightly, depending on whether you’re using powdered or liquid pectin.

When combining the fruit with the other ingredients, some recipes tell you to use a “preserving pan,” which simply means a heavy-bottomed pot that will heat evenly and keep the fruit and sugar mixture from scorching on the bottom.

If you’re making a jam without using commercial pectin, like the marionberry jam recipe below, then you’re relying on the natural pectin in the fruit to produce a jell. This is the style of jam I prefer because I believe it has a richer flavor and a more natural, softer consistency.

Making jam without adding additional pectin means you have to boil the fruit and sugar mixture until it reaches the “jell point” on your thermometer (see “Testing jams for doneness” below).

The width of your pot affects the speed in which your jam will reach the jell point. A wider pot — such as a 12-inch cast-iron skillet will cook the jam faster because there is a greater surface area cooking off the moisture in the fruit. Fast is good when making jam without added pectin.

6. At this point, remove the pot from the burner and take a breath. Good for you, you’ve just made jam. I like to carefully move the pot over onto the counter and place it on a thick layer of pot holders or a folded up kitchen towel. The jam needs this time to settle down. If there’s any foam on the surface, a lot of it will be reabsorbed during this 2- to 3-minute “rest.” After that, you can skim off any foamy residue with a spoon. (TIP: to keep foam from forming in the first place, consider adding 1/4- to 1/2-teaspoon of butter or vegetable oil to the jam while it’s cooking. Most recipes do not instruct you to do this, so you have to remember to do so all by yourself. It works amazingly well and doesn’t affect the flavor or safety of your jam.

7. Using a potholder, remove one of your clean jars from the oven and place it on the counter. Place your wide-mouthed funnel on top and ladle jam into the jar, filling to within 1/4-inch of the rim. You’ll need to actually measure that distance in this first go-round, but then you’ll have a visual image of how full the jars should be.

Since even tiny little splatters of jam on the jar rim can interfere with a good seal, dip a clean napkin or corner of a clean kitchen towel in some of the hot water that your lids are sitting in and wipe the jar rim.

8. Using your magnetic lid wand, fish out one of the flat metal discs from the pot of hot water. Shake off excess water, and place it on the jar rim with the sealing-compound side down against the jar rim.

Next, remove one of the metal screw bands, shake off excess water and screw it down onto the jar. Screw firmly, but not excessively. If you’re planning to process your jars in a boiling water canner (see step 9), then place your filled and closed jar in the pot of hot water using a jar lifter.

Repeat the filling and closing with all of the jars, placing each one in the pot as it is filled and closed. You will probably run out of jam before you run out of jars.

9. Processing your jars in a boiling water canner (or not): If you have enough refrigerator space, you can simply store your jams in the refrigerator without further ado (after they’ve rested for several hours on the counter). They will hold their quality well beyond one year.

But if you want to make your jams “shelf stable,” so they can be stored at room temperature without molding or otherwise suffering in quality, you need to process the jars in a boiling water canner. In some cookbooks, this procedure is called a “boiling water bath.” Use a pot that is deep enough to ensure that the jars are covered by at least 2 inches of water, and that there will be 2 inches of pan left to keep the boiling water from bouncing out.

When the jars are filled, lids screwed on, and placed in the boiling water canner, bring the water to a boil. Your recipe will give a processing time. The processing time begins once your water has reached a boil. After the jars have been “processed” for the required amount of time, remove them with your jar lifter and place them on a towel in a draft-free area of the kitchen.

10. Wait for the “ping.” The most satisfying sound to a food preserver’s ear is the tell-tale ping, signifying that a vacuum has been formed and the jar is sealing properly. The ping occurs as the lid is sucked down from its convex to concave position. It occurs anywhere between the first few moments after removing the jars from the canner up to an hour or so. After the jars have completely cooled, check the seal by pressing down on each lid. If it’s truly sealed, the surface will be solid and won’t bounce back to your touch. Place unsealed jars in the refrigerator.

Final thought on sealing: Typically, jars of jam will seal even if not put through the 10-minute processing in boiling water, so if you’re opting for putting your jams in the refrigerator without processing them, you may hear that tell-tale “ping” anyway. But I’ve found that the seal on a nonprocessed jar is not always as firm and reliable as one that forms after 10 minutes in a boiling water canner.

Testing jams for doneness: With added pectin, jams, preserves and marmalades will be done when they are boiled according to the individual instructions given in the recipe.

Without added pectin, jam is done when it reaches 8 degrees above the boiling point of water. And remember, because water boils more quickly the higher up you go on this planet; it tracks that adjustments would have to be made when determining the jelling point.

Thus, the jelling point is 220 degrees from sea level up to 1000 feet; 216 degrees up to 2,000 feet; 214 degrees up to 3,000 feet; 212 degrees up to 4,000 feet; 211 degrees up to 5,000 feet; 209 degrees up to 6,000 feet; 207 degrees up to 7,000 feet; 205 degrees up to 8,000 feet.

Marionberry jam

This is a very straightforward recipe. No extra pectin is added. And because it’s cooked in a wide, heavy-bottomed skillet, the cooking time is shorter than some recipes.

• 6 heaping cups marionberries, or other caneberries such as wild blackberries, loganberries and boysenberries

• 4 1/2 cups sugar

• 1/3-1/2 cup strained fresh lemon juice

• 1 teaspoon butter

Sort fresh marionberries, removing any leaves or twigs. Rinse them and drain them well. Gently stir the berries the sugar, and lemon juice (if the berries seem extremely ripe, use 1/2 cup of lemon juice; if at least 1/5 of the berries seem firm or even slightly underripe, then you can get away with the 1/3 cup of lemon juice because underripe berries contain more natural pectin) together in a bowl, using a rubber spatula; let the mixture stand, stirring gently once or twice, until the sugar has dissolved, about 2 hours (many times I let it sit all day in the refrigerator, or overnight).

Wash 7 half-pint jars. Keep hot until needed. Prepare lids as manufacturer directs.

Scrape the mixture into a large, wide, heavy-bottomed nonaluminum pan (such as a 12-inch cast-iron skillet). Add the butter and bring the mixture to a boil. Boil rapidly, stirring occasionally at first, and then constantly toward the end, until the mixture reaches the jell point on your thermometer (220 degrees from sea level up to 1000 feet; 216 degrees at 2,000 feet; 214 degrees at 3,000 feet; 212 degrees at 4,000 feet; 211 degrees at 5,000 feet; 209 degrees at 6,000 feet; 207 degrees at 7,000 feet; 205 degrees at 8,000 feet), which usually only takes about 7 to 10 minutes. Remove from heat.

The butter helps reduce foam, but if some foam remains after you’ve removed the pot from the burner and let the jam settle for about 2 to 3 minutes, skim it off. Ladle hot preserves into 1 hot jar at a time, leaving 1/4-inch head space. Wipe jar rim with a clean, damp cloth. Attach lid. Fill and close remaining jars.

At this point, if you want to store the jars at room temperature, place them in a large pot with enough hot water to cover the jars by 2 inches, bring the water to a boil, and process for 10 minutes (at elevations of 1,000 to 3,000 feet, process for 15 minutes; 3,000 to 6,000 feet, for 20 minutes; above 6,000 feet, for 25 minutes).

If you plan to store the jars in the refrigerator, then simply let them cool on the counter and refrigerate. Quality will be good for at least 12 months.

Makes 6 to 7 half-pints.

Jan Roberts-Dominguez is a Corvallis, Ore., food writer, artist, and author of “Oregon Hazelnut Country, the Food, the Drink, the Spirit,” and four other cookbooks. Readers can contact her by email at, or obtain additional recipes and food tips on her blog at

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