How to Preserve Harvested Mushrooms – Part 2

4. Drying – The age old method of drying mushrooms is still one of the best methods of preserving mushrooms. Boletus edulis are seen all over Italy, dried and wrapped in often elaborate (and expensive) displays. Methods vary from good old sun/air drying to machine drying (dehydrators) to oven drying. Different methods give somewhat different results, but it is mostly a question of how elaborate and how much are you willing to invest to accomplish this. Many good home use dehydrators are on the market. Units with Temperature control are particularly versatile, especially in humid areas or during spells of rain.

Method – Slice/prepare mushrooms, set on drying trays or rack and sun dry (protect from insects and flies) or place in dehydrator or oven (very low temperature 100ºF to 150ºF) – Dry to low moisture level, place in air tight bags or jars and store. To re-constitute cover with warm or hot water 15 minutes to several hours (varies with species) until plumped up. Do not use only the water from the tap for your recipes; be sure to use the soak water from the mushrooms as it is richly flavored. Save it for other later uses if the recipe does not call for liquid. Freeze it if no immediate us is at hand. It’s worth it. David Arora mentions that the pore-masses from Boletes can be dried separately from the mushrooms, soaked to reconstitute not for the pore-masses, as they are slimy, but for the soak liquid reserved after wringing out the masses for uses in gravies, soups, etc. It is truly a wonderful use of something otherwise usually discarded.

Advantages – Drying preserves mushrooms for very long periods of time with little or no deterioration in flavor or quality. Drying actually intensifies the mushroom flavor of many species, especially the Boletes. Convenient and easy to store and use, requiring no special equipment or refrigeration.

Disadvantages – Drying often toughens or changes mushroom texture; many will not fry or sauté after being dried. Sometimes flavor changes character after drying occurs. Volatile flavors and aromas are often lost. Re-constituting does not necessarily restore good texture in many cases. Equipment can be elaborate and expensive.

5. Canning – Since mushrooms have insufficient acid, they are susceptible to Clostridium botulinum (botulin) contamination and require pressure canning to be safely canned. Refer to a reliable canning guide and follow manufacturers specifications and instructions exactly.

The mushroom commonly used for canning is the I. volvacea species. It looks like a tiny umbrella and its cap is white, occasionally tinged with gray, smooth in texture. This is the most popular mushroom not only in the Philippines, but in the entire Southeast Asian Region. Its growth is well suited to the tropical climate. It is best harvested at button stage and this is approximately on the 11th to the 14th day after spawn planting into bed. These, however, have a relatively short shelf life due to its high moisture content (85 to 95%). To preserve the produce for longer period the best known method applied is canning with 2% brine as medium. The canned product retains its fresh quality and has a shelf life of one year.

The technology for the production of canned mushroom involves the following steps:

  1. Sorting for sizes and to remove buttons that do not meet the right specifications for canning; i.e., too mature, too dark or spoiled.
  2. Trimming which involves cutting off portions of stem that contain soil or dirt and rather tough.
  3. Washing in running tap water to remove all sorts of adhering dirt and clean up the buttons.
  4. The buttons are then blanched in boiling water for 3-5 minutes prior to filling into cans with 2% brine.
  5. Exhausting of the half-sealed is done to remove all entrapped gases.
  6. Sealing is done with the use of an automatic can sealer and this is followed by sterilization at 1-psi for 17 minutes.
  7. Cooling under running tap water follows and then the cans are wiped dry and stored.

Advantages – Versatility of product. If properly done, anything can be canned, so stews, soups, preparations containing mushrooms can be prepared, then canned.

Disadvantages – Expensive, sometimes finicky equipment is necessary, complicated processes and preparation possible and very strict adherence to methods, procedures, And techniques is an absolute must. This is not a method to where one can cut corners.

6. Pickling – Pickling is an acid treatment and preservation process for foods, usually either lactic acid produced by brine or vinegar added directly to the items preserved. Follow only proven recipes and techniques from reputable guides. Extension services and pickling and canning books are good sources. Agaricus, especially the somewhat bland store bought varieties, Shiitakes, Oyster mushrooms, and firm puffballs all respond well to pickling.

Advantages – Marinated pickle broths give great flavors to mushrooms, taking bland varieties and giving them some excellent flavors. Great for parties, catered events, etc. As antipastos and hors d’oeuvres, etc. Relatively process to do at home.

Disadvantages – Recipes must be proven and techniques adhered to rigidly. Not a good medium for experimentation, as improper acid balance could lead to Botulism or other serious food poisonings.

7. Salting – Can be a preservation method in its own right or can be used to induce lactic fermentation. In Arora’s All the Rain Promises there is an anecdotal reference and recipe for Lactarius deliciosis as done in Russia, I believe. It works and ferments the mushrooms well, but it yields a very salty product. Less salt risks spoilage before fermentation begins. When I brought some to an NMMS meeting, many did not mind the salt levels, others did; personal salt likes/dislikes are likely to come into play here.

Salting to “dry” mushrooms is a technique similar to salting anchovies and other fish. The water is drawn out by the salt and allowed to drain of or evaporate, leaving behind preserved product. Soaking re-constitutes product but often requires multiple rinses, and as mushroom flavor is lost this way, it is better to air dry mushrooms if moderate quantities or more are to be used. But for small amounts to bring up salt levels of a dish, this remains a very good method.

Advantages – Preservation stable and can actually change the cooking qualities less than full drying does, so some versatility exists here for texture with cooking. Easy to do and stable end product.

Disadvantages – mainly in high salt concentration forcing use of smaller quantities, or repeated rinses which leaches flavor needlessly. A first quick, but thorough rinse to remove salt before the mushrooms absorb much water helps to minimize this problem.

author: John Rahart of

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