Hmmmm If that's true then it's a wonder that my Grandparents and Great-Grandparents survived. I think the USDA might be a bit over cautious. But, I can see why the USDA is so cautious, they have warnings on their website not to use your dishwasher as a canner. People must do some really foolish things!
Anyway, I followed a standard recipe for canning store bought mushrooms and other non-acidic foods, 11 pounds pressure for 30 minutes. Maybe I should have cooked them for 45 minutes. Perhaps I will keep them in the fridge. I'm just telling you what I did so please don't look to me for advice, I've never canned mushrooms before. I've mostly canned Jams, tomatoes and Salmon. Jams and most tomatoes are acid enough not to need pressure cooking.
The chanterelles were boiled in a pickling broth before canning and the matsutake were cooked up as a soup first. All ten cans were hotpacked and pressure canned in a canner, not a cooker, at 11 pounds pressure for 30 minutes. I pressure canned the pickles because I used very little vinegar in them (I don't like strong pickles) and did not know if they were acidic enough to keep. I added a bit of veggie oil to the last two cans of pickled and pressure processed chanterelles. Strong pickles are acidic enough to be canned in a simple water bath.
Ok I have finally found some tidbids of advice on the interenet. I would not follow some of this advice, I'm just posting it for future reference.
My husband has been eating canned chanterelles since he was a kid. We can 3 hrs in a water bath, just like meat. We don't use a pressure cooker. Cook mushrooms down in boilong water, pack pint jars with cooked mushrooms and top with mushroom water to 1/2" from top, add 1/2 teaspoon salt.
From the web: http://www.backwoodshome.com/advice/aj88.html
Canning mushrooms is easy, but the experts now warn not to can wild mushrooms, because some people picked poisonous mushrooms by mistake and canned them up. I don’t often listen to “experts” who are trying to keep us safe from ourselves. Of course every mushroom hunter should only hunt mushrooms they can positively identify. That makes sense. And if you’re going to eat ‘em, why not can ‘em? I do. Frequently.
Be very careful in your picking, but I’m sure I don’t have to tell you that. Here’s how I can them:
Sort the mushrooms and soak in salted ice water for 10 minutes to remove any sand or insects. Morels often harbor both of these and are one of the best mushrooms. Can small mushrooms whole, removing any large, tough stems. Larger mushrooms may be sliced. Place in a pot and cover with water. Boil for 10 minutes. Pack hot into pint or half pint jars. Add salt (1 teaspoon to pints), if desired. Cover the mushrooms with boiling water to within half an inch of the top of the jar. Wipe rim of jar clean and place hot, previously boiled lid on jar, screwing ring down firmly tight. Pressure can only at 10 pounds pressure (adjusting pressure upward for higher altitude; check your canning manual for directions) for 45 minutes.
I use these wild mushrooms in a lot of recipes, from pizza to stews. They’re great.