title_body: How do beer manufacturers keep the taste the same?
upvoted_answer: I think this homebrew post has a good explanation of how brewers keep yeast strains. Homebrew yeast discussion
  
  White labs from San Diego also has a great slide about how they do it. White labs is the company just finished the study of the yeast domestication tree, where they analyzed the DNA of several yeast used in fermentation and determined how they are related. I've seen Chris White the founder speak at a homebrew event and it was very interesting. He has a Phd in microbiology from the university of california and sells to all sorts of professional brewers, distillers, and wine makers.
  
  I'll summarize the information from the references here, 
  but the bottom line is that they store samples at very cold temperatures so it's metabolism is almost shutdown and it won't evolve.
  
  
  Brewers isolate there yeast in slants or plates. These are the pure strain.
  The yeast that is isolated will be stored at a very cold temperature to remain dormant and unchanging. (-80 Celsius)
  When they need to recharge because their yeast has drifted they remove a small amount from storage.
  Using petri dishes they will grow a small size they can verify is still good.
  With this small batch they will add to wort (what brewers call the sugary liquid that makes beer) and then make a large batch of yeast.