How are expiration dates on food products determined?

Question

for example:

a cold sandwich at a convenience store contains all sorts of ingredients, such as lettuce, pickles, tomatos, and the like...each one of those ingredients has a different shelf life, so how is it that the sandwich expires on a specific date when all the different ingredients have a different shelf lives?

Answer 1

Different food products and how they are packaged are dated differently. "Open dating" is the use of a calendar date as opposed to a code on a food product. Open dating is found primarily on perishable foods such as meat, poultry, eggs and dairy products. ""Closed" or "coded" dating might appear on shelf-stable products such as cans and boxes of food. For detailed information on the way foods are dated see http://www.internet-grocer.net/exp-date.htm or http://onhealth.webmd.com/script/main/art.asp?articlekey=56270

Answer 2

From experience and testing the food companies come up with the shelf like that gives there products the same good quality attributes at the end of the labeled shelf life.

Answer 3

before they send the food out, they probably do different tests to find out how long food lasts

Answer 4

by the date they were manufactured