Why are the inner sides of the packaging such as instant noodles and potato chips all silvery reflective materials?
Again, why do you think it's shiny because of the heat seal inside the layer? You usually choose the transparent material, so you can see the bright aluminized layer through the transparent material
Specific to you said that these two products, packaging materials used formally referred to as composite film packaging bags, pay attention to the composite two words, is printed / aluminized barrier / thermal seal combination. It can be seen that the aluminum layer is not in direct contact with the food and is usually exposed to some safer plastic. Moreover, food packaging, regular enterprise products must be certified by the security, you can rest assured that eating.
In general this type of product itself is relatively more fat, more afraid of oxidation, such as fat rancid taste, in order to ensure the product shelf life, usually barrier on the packaging material requirements are relatively high. Aluminum is widely recognized as a material with good ductility and barrier properties, so it has been widely used in the field of food packaging.
