There are three places of bird's nest made in China: Yanyan in Huaiji County, Zhaoqing City, Guangdong Province, Yanzidong in Jianshui County, Honghe Prefecture, Yunnan Province, and Dazhou Island, Hainan Province (the island has been closed for protection). Bird's nest can be divided into three types due to different collection time: 1, Bai Yan, also known as Gongyan; 2. Mao Yan; 3, blood swallow. Bird's nest is nutritious, containing 50% protein, 30% sugar and some minerals. Jin Siyan saliva has the highest protein purity and nutritional value. Jin Siyan's lair. Most of them are built on the cliffs of tropical and subtropical islands. Below the cliffs are rolling waves and above them are blue sky and white clouds. Jin Siyan began to make nests in spring, and its mouth can secrete a kind of colloidal saliva, which is dried by the sea breeze and becomes a translucent and slightly yellowish substance, which is the main component of bird's nest. Jin Siyan made a nest with this saliva, slender seaweed, down feathers and soft plant fibers, which is what we call "bird's nest". Bird's nest is a precious delicacy, and it is also a valuable medicinal material. It has the effect of tonifying lung and nourishing yin, and is mainly used for treating cough and hemoptysis caused by fatigue. There is a "blood swallow" in the bird's nest, which is named because the food in Jin Siyan contains seaweed and other things, so its saliva is red silk. The bird's nest is half-moon, shaped like a human ear, with a diameter of 6-7 cm, a thick base and a thin profile, and weighs about 10/5g. The nest is neat in the periphery and rough in the interior, like a loofah network. The whole bird's nest is white, glittering and translucent, elastic and attached to the rocky cliffs. The nest built by Jin Siyan for the first time is completely condensed by a large amount of mucus secreted by their throats. It is pure and hairless. This kind of bird's nest has the best quality and is the top grade of bird's nest. In the feudal dynasty, it was often chosen as a tribute, so it was named "Guan Yan". After the bird's nest pickers seized the opportunity to pick the bird's nest, Jin Siyan had to make a nest for the second time. Because the spawning season was near, Jin Siyan was plump and had a lot of jelly in his throat, and the nest he built was relatively fat. However, due to time constraints, they brought feathers, grass ... and mixed with the jelly in his throat to build a nest again, which was rough, containing more impurities and poor nutrients. The bird's nest collected at this time is called "Maoyan". Another kind of bird's nest is moistened by the red liquid oozing from the attached red rock wall, which is dark red all over, also called "blood swallow" or "red swallow". It contains some minerals, has good nutrition and little yield, and is regarded as a treasure in bird's nest. Characteristics of high-quality bird's nest 1, thin and dense swallows (like there is no gap) 2, large and thick cup shape (about as big as three fingers folded) 3, Jamlom smell 4, dry hand feeling (keeping less water) 5, small amount of fine hairs in the cup 6, thin swallows 7, less internal capsule silk 8, bird's nest can be three to five times bigger on average after soaking in water. 9. The color of bird's nest is transparent, yellowish, shiny, and has the fragrance of bird's nest. Bird's nest gift box 1 Look at the hair head of bird's nest: different kinds of bird's nest also have different "hair heads" ("hair heads" means the difference in weight between bird's nest after being soaked and dried, and the greater the multiple, the better the hair head, the more it is eaten). Generally, official swallows have 6. It depends on whether the bird's nest is clean: the less fine hair, the better. 3 is the pick-up type: the thinner the head and feet at both ends of bird's nest, the more beautiful it is. 4 It depends on whether the bird's nest is dry and intellectual man fit: those who are dry and contain little water are the top grade. High-quality bird's nest should feel dry by hand. Wet bird's nest contains more water, and it will be moldy if it is stored improperly. Key points of identifying bird's nest: 1. Look: bird's nest should be filiform structure, and the piece structure is not a real bird's nest; Pure bird's nest is not completely transparent, but translucent, whether it is soaked or viewed under light. 2. Smell: Bird's nest has a unique fragrance, but it has no strong smell. Those with special smell, fishy smell or greasy taste are fakes; 3. Touch: take a small piece of bird's nest and soak it in water. After it is soft, take silk strips to pull it, which has poor elasticity. If it is pulled, it will be a fake; Rubbing with your fingers, those that can be rubbed into paste without elasticity are also fakes. 4. Burning: ignite the dried bird's nest slices with fire. If it is a real bird's nest, it will never produce any violent splash sparks.