There are three places of domestic bird's nest: Yanyan in Huaiji County, Zhaoqing City, Guangdong Province, Yanzidong in Jianshui County, Honghe Prefecture, Yunnan Province, and Dazhou Island in 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 Gong Yan; 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 cliff are rolling waves and above them are blue sky and white clouds. Jin Siyan began to build a nest in spring. Its mouth can secrete a gelatinous saliva, which is dried by the sea breeze and turned into a translucent 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 a "bird's nest". Bird's nest is a precious food and a precious medicinal material. It has the effects of tonifying lung and nourishing yin, and is mainly used for treating cough and hemoptysis caused by fatigue. The bird's nest is called "blood swallow" because Jin Siyan's food contains seaweed and other things, which makes its saliva contain impurities, so it is named Hongsi. The bird's nest is half-moon-shaped, shaped like a human ear, with a diameter of 6-7 cm, a thick bottom and a thin profile, weighing about 10- 15 g, with neat periphery and rough inside, like a loofah net. The whole bird's nest is white, glittering and translucent, elastic and attached to the rocky cliffs. The nests built by Jin Siyan for the first time were 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 "Yan Guan". After the bird's nest pickers seized the opportunity to pick the bird's nest, Jin Siyan had to build a nest for the second time. Because the spawning season is approaching, Jin Siyan is plump, with a lot of jelly in his throat, and his nest is relatively fat. However, due to time constraints, they brought feathers and grass ... and mixed them with the jelly in his throat to build a nest again. It was rough, with many impurities and poor nutrition. The bird's nest collected at this time is called "Mao Yan". Another kind of bird's nest is wetted by the red liquid oozing from the attached red rock wall, and its whole body is dark red, also called "blood swallow" or "red swallow". It contains some minerals, has good nutrition and low yield, and is regarded as a treasure in bird's nest. The characteristics of high-quality bird's nest are 1, thin and dense bird's nest (like no gap) 2, large and thick cup shape (about three fingers closed) 3, fishy smell of Jamlom 4, dry hand feeling (less water retention) 5, a small amount of fine hairs in the cup 6, thin bird's nest 7, less filaments in the inner capsule 8, and bird's nest can grow three to five times on average after soaking in water. 9. The bird's nest is transparent in color, light yellow and shiny, and has the fragrance of bird's nest. Bird's nest gift box 1 Look at the fur of bird's nest: different kinds of bird's nest also have different "fur heads" ("fur heads" refers to the weight difference of bird's nest after soaking and drying, and the greater the multiple, that is, the better the fur heads, the more you eat). Generally, there are 6 to 6 official swallows. It depends on whether the bird's nest is clean: the less fine hair, the better. 3 is the pick type: the thinner the head and feet at both ends of bird's nest, the better it looks. 4 See whether the bird's nest is dry or not, and whether it is intellectual: dry and low in water content is the top grade. A good bird's nest should be dry to the touch. Wet bird's nest contains more water, and it will be moldy if it is stored improperly. Identification points of bird's nest: 1. Look: bird's nest should be a filamentous structure, and the flaky structure is not a real bird's nest; Pure bird's nest is not completely transparent, but translucent, whether it is soaked or watched under the light. 2. Smell: Bird's nest has a unique fragrance, but it has no strong smell. Those with special smell, fishy smell or greasy smell are fakes; 3. Touch: Take a small piece of bird's nest and soak it in water. When it is soft, pull it with silk strips, which has poor elasticity. If it is pulled, it is a fake; Rubbing with your fingers, those that are inelastic and can be rubbed into a paste are also fakes. 4. Fire: Dry the bird's nest slices with fire. If it is a real bird's nest, it will never produce any violent splash sparks.