when determining the date by which a product will be of the best quality producers and retailers consider factors like the length of time and the temperature at which a food is stored while it s in transit and while it s being offered for sale 
other factors such as the particular characteristics of the food and its type of packaging will affect how long a product will be of optimum quality the date on perishable food is a good indicator of how long it has been sitting around in a warehouse or on the store shelves it also suggests that the product may or may not be at its best after the date on the label nevertheless these products still have some shelf life left in them if they re stored and handled properly a wise consumer will look smell taste or touch food to check whether it shows any signs of spoilage before throwing it out the usda maintains a food storage safety chart listing foods from sauerkraut to egg whites 10expiration dates for prescription drug patentsfor prescription drugs expiration dates have another unrelated meaning the u s patent and trademark office awards medical patents to pharmaceutical companies when a new brand name drug is released to the market the patent protects the drugmaker from having its drug copied by competitors for a certain time typically 20 years the patent exclusivity for orphan drugs lasts for seven years a patent for a new chemical lasts for five years 11the orange book a list of drugs that the fda has approved as both safe and effective cites the patents for new drugs along with their expiration dates 12under the hatch waxman act for a generic drug manufacturer to win approval for a drug the manufacturer must certify that it will not launch its generic product until after the original drug s patent has expired unless the patent is found to be invalid or unenforceable or the generic product will not infringe upon the listed patent 13