Fresh jellyfish contains a lot of water, has a thicker body, and also contains toxins. Only after being salted and alum-pickled three times (commonly known as "three alums") to dehydrate three times can the toxins be completely removed with the water. After three alum treatments, the jellyfish becomes light red or light yellow, is evenly thick and has a resilient texture, and no water can be squeezed out even with force. Only this kind of jellyfish is edible. When traveling to jellyfish-producing areas, you may encounter vendors selling jellyfish that has not been treated or has only been salted once or twice. You must not taste or buy it.
Fresh Daylilies
Also known as golden needles, the fresh, unprocessed product contains colchicine. Colchicine itself is non-toxic, but after being eaten, it is oxidized in the body into a much more toxic substance, called di-colchicine. According to experimental calculations, just 3 milligrams of colchicine is enough to cause nausea, vomiting, headache, and abdominal pain. A larger dose can lead to hematuria or hematochezia, and 20 milligrams can be fatal. Dried daylilies are steamed and processed, during which the colchicine is leached out, making them non-toxic.
Fresh Wood Ear Mushrooms
They contain a photosensitive substance called porphyrin. After consumption, exposure to sunlight can cause skin itching and edema. In severe cases, it can lead to skin necrosis. If edema occurs in the pharyngeal mucosa, it can cause difficulty breathing. Dried wood ear mushrooms are a finished product that has been sun-dried. During the sun-drying process, most of the porphyrin is decomposed. Furthermore, before consumption, dried mushrooms are soaked in water, which dissolves any remaining toxins, making the rehydrated mushrooms safe to eat.
Fresh Pickles
Fresh vegetables contain a certain amount of non-toxic nitrate. During the pickling process, it is reduced into toxic nitrite. Generally, nitrite begins to increase significantly 4 hours after pickling, peaks between 14 and 20 days, and then gradually decreases. Therefore, you should either eat pickles within 4 hours of being made, or eat them only after they have been pickled for more than 30 days. Nitrite can cause cyanosis and other hypoxia symptoms, and it can also combine with secondary amines in food to form carcinogenic nitrosamines.