The boiling process is one more step in brewing beer. This process makes sure it is sterilized and any form of bacteria is destroyed so no one becomes ill. The hops are also added at this time and it is usually boiled for 50 to 120 minutes. What happens when it is boiled? Here are several things that happen to beer during the boiling:
Boiling lowers the pH level in the wort so there is a stabilized environment for the hops
Boiling sterilizes using temperature and extracts the antiseptic hop resins
Boiling will destroy the enzymes so it does not continue to ferment, thus stops fermentation.
Boiling also coagulates unstable proteins
However, this is not all it does and why you have to keep a close eye on it. You have to keep a close eye on the different stages of the boil as well, like keeping the boil to rolling, violent roll or simmering. Boiling is a delicate process that flows into the many other steps of brewing beer.