Why do mushrooms smell like ammonia when cooking?

Mushrooms do not always smell like ammonia when cooking. This is typically dependent on the variety and freshness of the mushrooms used, as well as the cooking method.

Commonly, when mushrooms release an ammonia smell during cooking, it is due to the breakdown of certain amino acids, such as asparagine, into simpler compounds like ammonia. These amino acids are naturally present in some types of mushrooms, especially mature or older ones, and are not harmful. However, their breakdown during cooking can result in the release of ammonia gas, leading to the distinct odor.

Certain species, like shiitake and oyster mushrooms, are particularly known to have higher levels of these amino acids and therefore exhibit a stronger ammonia smell when cooked. Some wild mushrooms may also have a natural tendency to release more ammonia compared to cultivated varieties.

It's worth noting that not all mushrooms behave similarly. Some varieties, like button mushrooms, are known for their milder flavor and minimal ammonia release. Additionally, proper storage conditions and cooking techniques can help mitigate the ammonia odor. Using fresh mushrooms, storing them in a well-ventilated refrigerator, and avoiding overcooking can help minimize the release of unwanted aromas.