Kelp contains fucoidan and alginic acid. Once these substances absorb water, sticky colloid will appear on the surface of kelp, preventing water from entering further, so it is difficult to cook thoroughly.

In addition, the nutrients in kelp, such as water-soluble vitamins and minerals, will be soluble in water. If kelp is soaked for a long time, its nutritional value will decrease. If kelp is as tough as boiled after soaking in water, it means that kelp has gone bad and can't be eaten any more.

Seaweed soaking time:

Experts from the General Administration of Quality Supervision, Inspection and Quarantine reminded consumers that after eating kelp, it should be soaked in clear water according to the actual situation, and the water should be changed constantly, generally soaking in clear water for more than 6 hours. But if it is pollution-free kelp with guaranteed quality, don't bother, because the nutrients in kelp will dissolve in water if it is soaked for too long.

Extended data:

Edible taboo

1, don't drink tea immediately after eating kelp (tea contains tannic acid) and don't eat sour fruit immediately (sour fruit contains vegetable acid). Because kelp is rich in iron, the above two foods will hinder the absorption of iron in the body.

2. Hyperthyroidism patients should not eat kelp, because the iodine content in kelp is rich, which will aggravate the condition.

3. Pregnant women and lactating women should not eat more kelp. This is because iodine in kelp can enter the fetus and baby with blood circulation, causing thyroid dysfunction. As long as pregnant women ensure to eat kelp 1-2 times a week, they can meet the demand for iodine during pregnancy. The arsenic content in kelp is also very high, reaching 35-50 mg/kg, which is caused by seawater pollution.

Arsenic and arsenic compounds are toxic, and trivalent arsenic (such as arsenic) is the most toxic. Although pentavalent arsenic is less toxic, it can still be converted into trivalent arsenic in human body. The World Health Organization stipulates that the daily allowable arsenic intake of human body is 0.05 mg/kg. However, the arsenic content of dried kelp greatly exceeds the above standard.

According to the characteristic that arsenic can be dissolved in water, edible kelp can be soaked in enough water for 24 hours, and water should be changed frequently during soaking. After 24 hours, the edible kelp can be dried and stored for later use, which can ensure the safety of edible kelp and prevent arsenic poisoning. ) kelp has soft and hard function, and it is also suspected of abortion.

4, kelp can not be soaked for a long time, although it should be washed with water before eating kelp, but the time should not be too long. Generally speaking, soaking for about 6 hours is enough. If the soaking time is too long, the nutrients in kelp will dissolve in water, and the nutritional value will decrease.

5, special people should be careful to eat kelp, because the iodine content in kelp is rich, hyperthyroidism patients should not eat kelp, which will aggravate the condition; Pregnant women and lactating women should not eat more kelp.

6. In the coastal areas with high iodine, eating kelp as little as possible can prevent the occurrence of iodine excess diseases. In addition, excessive consumption of kelp may lead to thyroid cancer.

References:

Baidu encyclopedia-kelp (brown algae)

References:

People's Network-Kelp should not be soaked for a long time. Can I eat more kelp?

References:

People's Network-kelp is washed and soaked for 6 hours, so it is not suitable for eating in large quantities.