1. Comparison according to texture

1. Yanzhan is distinguished by "dense, fine, and sparse". The denser ones are classified as top-grade Yanzhan, and the sparser ones are classified as top-grade Yanzhan. Second class. Generally, the calyx type with complete fibers and dense fibers is classified as level one, and the calyx type with incomplete fibers and loose fibers is classified as level two.

2. According to the calyx shape, the calyx shape is complete and well-proportioned.

2. Comparison by bird's nest type

1. Official bird's nest: The first-stage bird's nest with a complete cup shape and few impurities is usually called "official bird's nest" or "tribute bird's nest". This kind of bird's nest is the most nutritious, has less impurities and has a good taste.

2. Feathered bird's nest: a bird's nest containing more bird feathers, or a second- or third-stage bird's nest. The nutritional content of this kind of bird's nest is not as good as that of official bird's nest, and it has many impurities and is difficult to handle.

3. Grass swallow: A bird's nest built in the grass, mixed with a lot of grass clippings, and the quality is the worst.

3. Identification of bleaching and dyeing

Normal bird's nests are light yellow, off-white or light gray or even have natural brown spots. However, bleached bird's nests will retain a certain chemical smell, while unbleached bird's nests will have a natural light fishy smell. Severe bleaching and dyeing will damage the internal structure of the bird's nest, and the texture will still be hard after soaking for a long time.

4. Gluing

Gluing is to increase the weight of the bird's nest by applying edible glue and hanging paste on the inside, outside and bottom of the bird's nest. In order to make the bird's nest dense. The surface of the glue-brushed bird's nest is reflective and dense. The color and texture of the glue-brushed bird's nest are unclear and integrated, giving people an airtight feeling. Put it in water and rub it with your thumb and index finger several times. Your fingers will feel sticky and sometimes smell chemicals.