Shelf life and expiry date

In general, the 'best before' date is the date when the taste is guaranteed, and the 'expiration date' is the date by which the food must be eaten.
This understanding is not wrong, but I will explain it in a little more detail.

The expiration date can be stored for a long time. (can be stored for more than 6 days)
Expiration date cannot be stored for a long time.

These deadlines are set by multiplying the maximum shelf life (maximum period during which there is no problem in taste and appearance sensory tests, and microbial and physical and chemical tests when properly stored) by a safety factor (0.7 to 0.9). It's becoming

For example, the maximum shelf life of a prototype is 10 days, and the expiration date is 8 days, which is the safety factor of 0.8.