Fresh Is Not Always Safer or More Nutritious
Fresh jellyfish contains high water content, thick skin, and toxins. Only after being washed twice with salt and alum (commonly known as "three-alum" processing) to dehydrate it twice can the toxins be fully eliminated. Two-alum jellyfish appears light red or pale yellow, evenly thick, resilient, and does not release water when squeezed—only such jellyfish is safe to eat. When visiting jellyfish-producing areas, avoid purchasing untreated jellyfish or those processed only once or twice with salt.
Fresh daylilies, also known as golden needle vegetables, contain colchicine in their raw form. Colchicine itself is non-toxic, but it oxidizes into highly toxic tri-colchicine in the body. Studies show that consuming just 3 mg of colchicine can cause nausea, vomiting, headache, and abdominal pain. Larger doses may lead to bloody urine or stool, and 20 mg can be fatal. Dried daylilies are processed by steaming and boiling, during which colchicine is leached out, rendering them non-toxic.
Fresh mushrooms contain a photosensitive substance called porphyrin. After eating, if exposed to sunlight, it may trigger skin itching, swelling, and in severe cases, skin necrosis. If swelling occurs in the throat mucosa, breathing difficulties may arise. Dried mushrooms are sun-dried products, where most porphyrin breaks down during drying. Before consumption, they are soaked in water, allowing residual toxins to dissolve, thus making rehydrated mushrooms safe to eat.
Fresh pickled vegetables naturally contain harmless nitrates from fresh vegetables. During salting, these nitrates convert into toxic nitrites. Typically, nitrite levels begin rising after 4 hours of pickling, peak between 14–20 days, then gradually decline. Thus, either consume pickled vegetables within 4 hours of salting, or wait until they’ve been pickled for over 30 days. Nitrites can cause cyanosis and oxygen deficiency, and may combine with secondary amines in food to form carcinogenic nitrosamines.
Bottled Water Marketed bottled water—whether distilled, mineral, or other purified types—is usually treated with ozone as final disinfection before bottling. Newly filled bottles therefore contain relatively high concentrations of ozone. Ozone is toxic to humans; drinking freshly bottled water means ingesting poison. If left standing for 1–2 days, ozone dissipates naturally. According to regulations, bottled water must undergo inspection and testing for 48 hours before release. Therefore, only bottled water that has passed this standard is safe.