Cicerone Certified Beer Server Exam Study Guide Part V – Off-Flavors

This is Part V of a series on knowledge for the Cicerone Certified Beer Server Exam. All information disseminated is from the syllabus provided by the Cicerone website and mixed with my own thoughts. I’m doing this to 1) help me learn the material and 2) share the knowledge with people who haven’t heard of the exam or are planning to take the exam.

Feel free to skip ahead to other sections. Here’s a list of all the study guide parts:

This is Part V on Off-Flavors.

Recently I’ve been diving into learning off-flavors on my journey to becoming a Cicerone Certified Beer Server. On the exam, off-flavors will probably only be a handful of the 60 questions. But it’s a topic I need to study up on since you need to get a 90% to pass (that’s 54/60 right).

Most of this information is taken out of John Palmer’s How to Brew, which is available for free online, and the BJCP website. Here are a couple of key off-flavors and a basic overview about them.


  • Tastes like fresh green apples. It is an intermediate compound in the formation of alcohol. This essentially means the beer is too young and it needs more time to condition.


  • It is mouth puckering and has a husk-like graininess taste. It’s similar to sucking on a tea bag. It is usually the result of steeping grains for too long or the pH of the mash exceeding a range of 5.2-5.6.


  • Tastes like butter or popcorn. It is the result of the normal fermentation process or a bacterial infection. It is usually because of weak yeast or insufficient aeration.

Dimethyl Sulfides (DMS)

  • Tastes like cooked corn. Outside of pale lagers, it is the result of poor brewing practices or bacterial infections. When it’s from a bacterial infection it tastes like cooked cabbage. In short, cool down the wort as quickly as you can before pitching yeast or DMS will reform.

Light-Struck or Skunked

  • It tastes skunky. This is from being exposed to sunlight or fluorescent lights. Brown bottles protect much better than green or clear bottles but they still shouldn’t be left in the sunlight or under fluorescent lights (like in a grocery store).


  • Tastes stale or like wet cardboard. This happens when beer is exposed to oxygen post-fermentation. This can be from a number of sources including bottle caps and keg seals. If your beer is old, it’s probably oxidized.


Once I take the CBS exam I’ll update this and the other parts of the study guide. If you’ve taken the exam feel free to add comments on these off-flavors or other ones that I might need to know to pass it.

Happy studying and good luck on the exam! Remember to check out the other posts. Here they are again:

If you passed the exam and/or used any of these posts as help, I’d love to hear about it. Leave your thoughts on them, the exam or anything else below!