title_body: Found around 10kg of 18 year old vacuum sealed coffee beans. Safe to consume?
upvoted_answer: 18 years might be pushing it, and that is impressive!
  As a side thing, I would honestly love to try some.  
  
  I am not saying that it will definitely be bad, or definitely be good before a certain amount of time, and that is subjective as well..."good" and "bad" being if they still have flavor or taste rancid.  The question is about "safe to consume", with the side topic of being "good flavor".    
  
  Normally, Coffee has a shelf-life about 3-9 months, depending on if its ground, whole, flavored, and how and where its stored.
  That may spark some arguments though, but the question is about "safe to consume" not flavor.
  At a store, they would not have a bag of coffee on the shelf for more than 1 month from roasting, regardless of how its sealed.
  Looking at food vacuum seal places, they say that coffee sealed will last up to 3 years vacuum sealed.
  Link 1 to vacuum bag shelf-life
  Link 2 to vacuum bag shelf-life  
  
  I found this article specifically about coffee and has a chart and table for that.
  This is right in line with the other articles and what I mentioned above.
  
  Those are all recommendations, and there is good reason.  Usually with any vacuum seal there is some oxygen that gets into the product and that will cause it to degrade over time.  The oxygen is part of the air, which may also contain some moisture.  The moisture will also degrade the product over time, creating an environment for bacteria to grow in.  Bacteria needs oxygen and moisture to grow, and the reduced oxygen slows down the process of spoilage and creates an environment to limit the growth, while also limiting the evaporation of any moisture in the food (thus it retaining its flavor).
  Also, the vacuum seal can and will degrade over time itself eventually letting in some oxygen and moisture.  This is different depending on the packaging and type of seal.  This is based on the manufacturer of the vacuum seal as well, though some are better than other, often the manufacturer will put a date/time on the seal knowing it will last longer than that but that is the less than minimum, so that way its not an issue when the seal does give.
  
  Typically, when coffee goes bad there could be some mold IF its exposed to moisture for a long period of time, but usually it would just lose its flavor and possibly some of the caffeine.  You can tell if its gone bad by the smell when you open it.  If when you opened it, and it smells of mildew or mold, then its definable bad, and that would be bad to drink.  If its just odorless and bland smell, then it is probably still good to drink, but probably won't have any flavor.  Coffee like that, will not be harmful to you, just not be "good" to taste (but also probably not "bad to taste either).  
  
  
    Though I did find some very fine lint type things inside. If you ask me it looks like the ends of a dandelion.
  
  
  That could have been some of the beans breaking down, or just a bean that got crunched in the packaging a while ago.  Depends on the coloration and smell and such.  Personally, I would try that at all.
  
  If you already brewed it and didn't find any bad taste, smell or feeling from drinking it, then its probably good.  Additionally, you could also blend this coffee with other fresh coffee, assuming its still "good" based on the above.  
  
  Found this article and this gives more details on it going "bad".