title_body: What is a FlavorLock™ bag?
upvoted_answer: This question is actually answered on the website of the coffee producer.
  
  To summarize, the roasting process of coffee produces carbon dioxide inside the beans, which takes a while to find its way out. Sealing the coffee in tight containers would be problematic, as the carbon dioxide would stay in the beans in this way (making the coffee sour) or may let the bag burst over time.
  
  However, not sealing coffee bags is not a solution either, as exposure to air lets the coffee get stale after a while. As supermarket coffee is unfortunately often stored for long period of time before sold, this would be problematic.
  
  So the solution is to either (1) use a one-way valve that allows the carbon dioxide to escape from the bag without the air coming into the bag, or (2) to let the beans degas before sealing them airtight in bags. Solution (1) is probably best for fresh coffee, so it is used here. I don't know what problem is solved with such valves in pet food containers.