Continuing our series on off-flavors we're going to look at what happens and how to deal with beer-spoiling bacteria and wild yeast infect your brew. 

What is it?

Infection occurs when beer-spoiling bacteria or wild yeast make it into beer and start competing with cultured yeast for sugars.  The typical off-flavors to look out for are sour and/or diacetyl (buttery).  Other common flavors that indicate an infection is soy sauce, solvent, and vinegar.  Wild yeast infections can carry the barnyard, goat, or horse-blanket. 

How does it form in beer?

Infections typically occur when cleaning regimens aren’t adhered to, or when care isn’t taken when adding ingredients on the cold side of fermentation. 

 How do you solve the problem?

Infections are easy to stave off if a good cleaning regimen is adhered to and care is taken when adding ingredients on the cold side of brewing.  Special care is needed when packaging beer – always make sure the lines are sanitary and the system is in a closed loop.