Specifically, it depends on how well it has been preserved. If it is a gum product, such as gum cake, gum date, etc., expired can not be wanted. Usually, the shelf life of Colla Corii Asini is five years, if the shelf life, properly preserved, no deterioration can be eaten.

The way to determine the deterioration of Colla Corii Asini:

1, cracked or broken

The phenomenon of cracks on the surface of the glue block, some of which will be broken with a light touch. This is mainly due to the gum storage space is too dry or storage process wind blowing, gum water content is low and other reasons. When the water content of Colla Corii Asini is lower than 10%, the glue block will have cracking phenomenon, or even broken.

2, softening and melting and adhesion

The water content of Colla Corii Asini should be controlled at 15% or less, and the storage temperature should be controlled at 20℃ or less. In such conditions storage of gum generally does not occur softening and melting phenomenon. However, if the storage conditions change, the gum moisture or heat is easy to soften, and may even dissolve. Adhesion refers to the glue block and glue block or packaging materials stick together, often due to storage room temperature is too high or humidity is too large, packaging is not tight and other reasons.

3, mold and discoloration and odor

Mold: amino acid is a good nutrient for mold. When the surface of the gum stained with mold spores, in the case of temperature, humidity is appropriate, the surface of the gum block will form a natural mold medium, prompting the rapid growth of spores, there will be a white, different shapes of mycelium, mold.