If you are short on freezer space, there are still some other options to save the extra mushrooms that you have acquired. Drying mushrooms is another good way to store them for future use.
How to Preserve Mushrooms by Drying
If you do not get a dehydrator, you could try setting up an oven at a similar temperature, or as low as you can get it, and drying mushrooms with the doors cracked open so that any excess moisture escapes easily. Either way, it should take about six to twelve hours to completely dehydrate the mushrooms.
If you would like them drained slightly faster, you can crank up the heat a little higher. But I would never go above 50 degrees C (122 degrees F). If you go too hot, mushrooms lose most of their flavor. To keep your mushrooms dry, you need to slice them extra thin. About 1/4 inch to 1/2″ (0.6 to 1.3 cm) is the best.
Anything thicker than that, and you might have trouble getting all of the moisture out. Cut them as evenly as you can, as thinner pieces dry faster than thicker ones. If there is too big of a difference, you will need to take the thinner ones that are drying down one at a time, so that they do not begin to burn. Some mushrooms are harder to slice evenly than others. If you cannot cut them evenly, at least try sorting different sizes in different areas of a dish, or in individual dishes.
Just as you would when freezing your mushrooms, first brush them well to remove a lot of dirt from the mushrooms surfaces. Then pat them dry with a paper towel before cutting. Start checking on the dryness around the six-hour mark.
Remove anything that is completely dry. They should break in half when you try to fold them over, and they will look crunchy. Check any that are not yet dry every 30 minutes to an hour. Once you have removed your dried mushrooms from the oven or dehydrator, allow them to sit on a counter to cool at room temperature for about an hour, or until completely cool when you touch them.
If any of the chilled mushrooms still feel bent or moist, return them to the baking tray to continue drying. Once your dried mushrooms are cold, you can store them in a sealed bag or in a glass jar with a tight-fitting lid. Keep the mushrooms in a cool, dark place, where they should remain fresh for anywhere from 6 months to one year. You will know they are not any good anymore when they begin to lose the smell of mushrooms.
When you want to rehydrate dried mushrooms, place them into a bowl and pour boiling water on top. Then, allow them to soak for about twenty to thirty minutes.
Dried mushrooms are great additions to sauces and soups.
How to Pickle Mushrooms to Preserve Them
One less common way of preserving mushrooms you may not have thought about is pickling. Just like you would pickle cucumbers or eggs, you can pickle mushrooms to keep them longer, and they have an amazing, slightly acidic flavor.
Start by cleaning out any mud on the mushrooms. You can wash them in cold water, as they are going to sit in the liquid anyway.
Large mushrooms can be cut in quarters or halves, or you can leave smaller ones whole. Button mushrooms are small enough that they can be picked up whole, but larger cremini or portobello mushrooms probably will have to be cut.
Start your pickling process by gathering a few herbs, such as bay leaves, thyme, oregano, dill, rosemary, or garlic.
You will also want to pick up mason jars with 1L (1Quart) capacity, which will hold up under the rigors of temperature changes. You will also need to get jars with covers you can seal tight.
Get a non-reactive pot (made from stainless steel, glass, or ceramic) and fill it with 180ml water and 89ml white vinegar. Add the desired quantity of spices to the brine, along with around 1 tbsp of salt and 1 tbsp black pepper. Drop the mushrooms in the brine, and bring the entire mixture to a simmer on a high heat.
Then lower your heat to low and allow the mixture to boil down for about fifteen minutes. After fifteen minutes, remove the mixture and put into your pickle jar. Do it slowly so you do not burn yourself.
You may need to use a spoon to transfer mushrooms to prevent them from splashing as they drop in your jar. Use the spoon to pick up any herbs that are left on the skillet, too, and add those to the jar.
Let the mixture cool at room temperature for about 30 minutes to one hour. Then put an airtight cover on your jar and put in the fridge. The difference in temperature will seal the jar, keeping things fresh.
Wait around three days to allow the cured mushrooms to soak up all of the spices and vinegar in the jar, then taste test. Your jars will keep well for at least one month in the refrigerator.