Mushrooms are culinary "sponges" that require specific handling to achieve their best flavor and texture. Because they are roughly 80–90% water, the primary goal of preparation is to manage moisture.
Remove mushrooms from plastic wrapping immediately. Store them unwashed in an open paper bag in the refrigerator; the paper absorbs excess moisture and prevents them from becoming slimy. MUSHROOMS
Look for caps that are firm and whole with an even texture. Avoid mushrooms that are withered, damp, or slimy, as these signs indicate they are past their prime. Store them unwashed in an open paper bag
To avoid "rubbery" or "soggy" mushrooms, use methods that drive off moisture before browning begins. How To Cook Mushrooms - Michael Ruhlman To avoid "rubbery" or "soggy" mushrooms, use methods
While many recommend brushing off dirt with a damp paper towel or pastry brush to avoid "waterlogging," testing shows that a quick rinse only increases mushroom weight by about 2%.
Trim the very bottom of the stems. Keep mushrooms whole, quartered, or sliced depending on the recipe, but remember that smaller pieces release moisture faster. 3. Essential Cooking Techniques
Most fresh mushrooms last about one week in the fridge when stored properly. 2. Cleaning and Preparation