Canning Mushroom Soup Base

Canning mushroom soup base puts the start of a warm, savory dinner on your pantry shelf, ready to finish into a creamy mushroom soup or stir into casseroles, gravies, and pan sauces whenever you want it. You do the chopping and simmering once, and then a jar opens to a deeply flavored base that only needs cream and a quick thickener at the stove.

This recipe comes from Pressure Canning for Beginners and Beyond by Angi Schneider, and she built it on the National Center for Home Food Preservation’s tested process for canning mushrooms. Every solid that goes into the jar (mushrooms, onions, garlic, and a few dry spices) has its own home canning basis, and each one processes in less time than mushrooms do, so the whole batch is held to the mushroom process to keep everything safe. It is a low acid recipe, which means it has to be pressure canned, and it lands in the vegetarian soup canning recipe category if you use vegetable broth.

One thing to know going in is that you are not actually canning finished cream of mushroom soup. You are canning the base, since cream and flour are never safe to add before processing. Everything else goes in the jar, and the cream and thickener get stirred in at serving, which takes only a couple of minutes. The recipe fills 8 pint jars, and because the mushroom process has no tested time for quarts, this one is for pints only.

Choosing Mushrooms for Soup Base

You can use any cultivated mushroom you like here, from everyday white buttons and criminis to shiitakes and oyster mushrooms, as long as they were grown for eating. The flavor and color of the finished base will shift a bit with the variety, so this is a good place to use whatever looks good at the market or whatever you grow.

The one hard line is that wild foraged mushrooms are off the table for canning. They have not been tested for home canning, their density and water content vary too much from one to the next, and there is no safe process for them in a jar. Stick with cultivated mushrooms, and if you have wild ones to preserve, dry or freeze those instead.

Look for firm, dry mushrooms with tight caps and no slimy spots. Slice them fairly evenly so they cook at the same rate and pack down to a similar density, which matters when you are filling jars by solids first.

Keep in mind that mushrooms shrink a good deal as they cook, so 2 pounds of sliced mushrooms in the pot turns into much less once they have given up their water. That shrinkage is normal and expected, and it is why the broth and wine do a lot of the work of filling the jars.

If you want to lean a base in a particular direction, shiitakes give it a meaty, savory edge that pairs well with a splash of soy sauce, while a mix of criminis and oysters keeps things milder and more rounded. Any of these can stand in for the plain mushrooms in the recipe without changing the process.

Ingredients for Mushroom Soup Base

This makes a full canner load of 8 pint jars. Everything in the list below is safe to process, and the quantities are what keep the base within the tested mushroom process, so measure the mushrooms, onions, and garlic rather than eyeballing them.

• Mushrooms: The heart of the base. Use any cultivated variety, sliced fairly thin. See the section above for more on choosing them, and the standalone canning mushrooms recipe if you want them plain in a jar.
• Onions and Garlic: Onions are safe to can on their own and process in less time than mushrooms, and a few cloves of garlic are allowed in pressure canning recipes without affecting safety. Together they build the savory foundation of the base.
• Broth or Stock: Use chicken, beef, or vegetable broth, homemade or store bought. Vegetable broth keeps the recipe vegetarian. Homemade vegetable broth or chicken broth both work beautifully here.
• Dry White Wine: Adds depth and a little acidity to balance the earthy mushrooms. Wine is fine for pressure canning. You can leave it out and use extra broth or water in its place if you prefer.
• Salt, Pepper, and Thyme: Dry spices in reasonable amounts are allowed, meaning enough to season but not enough to turn the mix into a paste. The salt is for flavor, not preservation, so adjust it to taste.

The cream and a spoonful of flour for thickening are left out on purpose, and they get added at serving rather than before canning. Dairy and thickeners are too dense to let heat move safely through the jar, so they always wait until you reheat a jar to serve.

For the wine, any dry white you would cook with is fine, and you do not need anything fancy. The alcohol cooks off during the simmer, leaving behind acidity and flavor that round out the base.

If you would rather skip the wine entirely, add an extra cup of broth or water in its place. The base will be a little less complex but still good, and the process stays exactly the same either way.

The recipe uses 4 teaspoons of salt across the whole batch, which brings out the flavor of the mushrooms. Since the salt is there for taste and not for safety, you can reduce it or leave it out and season later when you use the base.

I use canning salt, which is a fine grained, additive free salt. Other additive free salts like sea salt, kosher salt, and Himalayan salt also work. Skip iodized table salt, since the additives can cloud or discolor the jars. There is more in my guide to canning salt and substitutions if you want options.

When it comes time to fill the jars, you will leave a generous 1 inch of headspace, which is standard for pressure canning a chunky, brothy pack like this one. That space gives the contents room to move during processing without pushing up against the lid.

Have a kettle of water going while you fill, just in case the jars come up a little short on liquid. A splash of boiling water tops them off to the right headspace, though I usually reach for more broth first.

At serving, you will also add, per pint jar, about a quarter cup of heavy cream, a tablespoon of flour for thickening, and fresh thyme or parsley to taste. None of those go in before canning, so set them aside for later.

How to Make Mushroom Soup Base

The method is simple. You saute the aromatics and mushrooms, add the liquids and spices, boil everything briefly, and pack it hot into jars. The short boil before packing is not optional, since it drives air out of the mushroom tissue and makes sure everything is evenly heated before it goes into the canner.

This is a hot pack recipe, so it helps to have the canner warming and the jars hot before you start filling. Read through the steps once so you have your jars, lids, and pressure canner ready to go when the base comes off the heat.

Prepare the Ingredients and Heat the Canner

Start by setting up your equipment. Put a few inches of water in the pressure canner according to your manufacturer’s instructions, set your clean pint jars inside, and bring it up to a low simmer to keep the jars hot. Since this is a hot pack, you want the canner around 180 degrees Fahrenheit, or 82 degrees Celsius, by the time you are ready to load it.

While the canner heats, prep the vegetables. Slice the mushrooms fairly thin, dice the onions, and mince the garlic. Having everything cut and measured before you turn on the stockpot keeps the cooking moving smoothly.

Measure your broth and wine and have them within reach, along with the salt, pepper, and thyme. Once the mushrooms hit the pot things go quickly, so it pays to have the liquids ready to pour.

If you are using homemade stock straight from the fridge, there is no need to heat it separately. It will come up to temperature in the pot along with everything else during the simmer.

Remember that there is no approved process for canning mushrooms in quarts, so set out pint jars only. Both half pints and pints are processed for the same 45 minutes, so you can use either size or a mix of the two.

Saute the Onions, Garlic, and Mushrooms

Melt the butter in a large stockpot over medium heat, then add the onions and garlic. Cook them gently for about 15 minutes, stirring now and then, until the onions are soft and translucent and the kitchen smells like the start of something good.

You can use olive oil in place of the butter if you want to keep the base dairy free up front, which makes sense if you plan to finish some jars without cream. Either fat works the same way for sauteing.

Once the onions are translucent, add the sliced mushrooms and saute for another 5 to 10 minutes. They will release their liquid, shrink down, and pick up a little color, which is exactly what you want before the broth goes in.

Give everything a good stir as it cooks so the mushrooms brown evenly and nothing sticks to the bottom of the pot. The mix will look like a lot less than what you started with, and that is normal.

At this stage the base is all aromatics and mushrooms, concentrated and savory. Take a moment to make sure the onions are fully softened, since they will not cook much further once the liquid goes in.

If any garlic looks like it is browning too fast, lower the heat a touch. You want it fragrant and soft, not toasted, so it melts into the background of the finished base.

Simmer and Pack the Jars

Add the broth, wine, salt, pepper, and thyme to the pot and bring everything up to a boil over medium high heat. Because the pot and the mushroom mixture are already hot, this happens fairly quickly.

Once it reaches a good rolling boil, set a timer and let it boil for a full 5 minutes. This step drives air out of the mushrooms and heats the base all the way through, so do not skip it or cut it short.

Take the pot off the heat and ladle the base into your hot pint jars. Spoon the solids in first, dividing the mushrooms and onions as evenly as you can across all 8 jars, then go back and top each one with the broth.

Distributing the solids first matters, because the mushrooms may not fill the jars on their own after shrinking. Getting roughly the same amount of solids in each jar keeps the batch consistent from one jar to the next.

Leave 1 inch of headspace in each jar. That space helps prevent siphoning and liquid loss during processing, and it gives the contents room to bubble without disturbing the seal.

Measure the headspace rather than guessing, since it does affect how the jars seal. A headspace tool or a clean ruler makes this quick.

Run a bubble removal tool around the inside of each jar to release trapped air, then check the headspace one more time. If a jar has dropped below 1 inch of liquid, top it off with a little more broth or boiling water.

Trapped air pockets can throw off the seal and leave you with less liquid than you expected after processing, so it is worth taking a minute to debubble every jar.

Wipe the rim of each jar with a clean, damp cloth to remove any splashes of broth, since a clean rim is what lets the lid seal properly. Center a lid on each jar and add the band, tightening just to fingertip tight.

Fingertip tight means snug but not cranked down, so air can still escape during processing. Once the jars are lidded, load them into the hot pressure canner.

Canning Mushroom Soup Base

This is a hot pack, pressure canned recipe, and the minimum batch for safe processing is 2 quarts or 4 pints. This recipe makes a full canner load of 8 pints, so you are well above the minimum, but it is worth knowing if you ever want to scale down.

To can, prepare your pressure canner, jars, and lids. Pack the jars to 1 inch headspace, remove the air bubbles, wipe the rims, and apply the lids and bands fingertip tight. Load the jars, lock the lid, and vent the canner with a steady stream of steam for 10 minutes before bringing it up to pressure.

Process the pint jars for 45 minutes at 10 pounds of pressure in a weighted gauge canner, or 11 pounds in a dial gauge canner, adjusting for altitude using the table below. This recipe is for pints only, since the mushroom process has no tested time for quarts.

When the time is up, turn off the heat and let the canner depressurize on its own. Never force cool a pressure canner, since a sudden drop in pressure can cause liquid loss and seal failures.

Once the canner has fully depressurized, remove the lid away from your face, lift out the jars, and set them on a towel to cool undisturbed for at least 12 hours. After that, check that every lid has sealed, label the jars, and store sealed jars in a cool, dark place for up to 12 months.

Tips for Success

The most common snag with this base is coming up short on liquid, since mushrooms shrink so much in the pot. If your batch looks like it will not fill all 8 jars, lean on extra broth and wine first, and keep a kettle of boiling water going as a backup to top off any jar that needs it.

Resist the urge to overfill the jars with solids in an effort to use everything up. The half solids, half broth balance is what lets heat move through the jar during that 45 minute process, and packing it too densely works against safe heat penetration.

Finally, label your jars with the date and contents. The base looks similar to a few other canned soups on the shelf, and a quick label saves you from guessing in six months.

If you find yourself making this often, it scales nicely to back to back canner loads. Just keep each batch measured to the recipe so the ratios, and the process, stay correct.

Serving Ideas for Mushroom Soup Base

To turn a jar into cream of mushroom soup, pour the base into a medium pot and heat it over medium heat for about 10 minutes, until it is bubbling. Stir in roughly a quarter cup of heavy cream per pint, along with a tablespoon of flour whisked into a little cold water to make a slurry, then bring it back to a boil for a minute or two until it thickens. Finish with fresh thyme or parsley and serve it alongside crusty bread or a salad.

The base is just as useful as an ingredient as it is a soup. Use it in place of canned condensed soup in casseroles, pour it over chicken or pork in the slow cooker, or stir it into a pan of sauteed greens and noodles. For more pantry meals like this, browse the full collection of soup canning recipes and the meal in a jar canning recipes.

Because each jar is already seasoned and full of mushrooms and onions, it takes very little to round it into a meal. A handful of cooked rice or noodles stirred in at the end, or a piece of toast on the side, is often all it needs.

A few questions come up often with this one, so here are the answers before you get started.

Mushroom Soup Base FAQs

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