Confessions of a Fermentation Geek: Why Fermentation Deserves Our Respect

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Confessions of a Fermentation Geek: Why Fermentation Deserves Our Respect

How many homebrewers can say they started bottling beer at seven years old? I can and I’m darn proud of it. My parents have been homebrewers since the 1980s. A self-professed science geek, watching my parents turn water into beer is what started my fascination with chemistry, and, more specifically fermentation.


The fermentation process is what makes beer…beer. The characteristics that make this golden liquid unique, a thick foamy head and a constant flow of bubbles cascading to the surface, are due to this magical process. 


All hail yeast

One of the most important ingredients in the beer making process, yeast transforms “sugar into alcohol and carbon dioxide”, during the process of fermentation. Here’s a look at how this happens: 

  • During the mashing process starches in the malt are broken down into small chain sugar molecules such as glucose and maltose.
  • The main goal in the mashing process is to have saccharification which means turning the starches into fermentable sugar which the yeast converts into alcohol and carbon dioxide.

Sounds pretty straightforward, right?

Well, it’s not always that easy. A brewer needs to take lots of small details into account for saccharification to occur.  A brewer needs to consider:

  • Temperature needs to be 66°C/150°F for the enzymes to perform their best.  Enzymes alpha and beta amylase are needed to break the bonds present in starches to create the fermentable sugars.
  • Time is also needed. Usually an hour to convert the starches into smaller fermentable sugars, glucose and maltose.

Activating the yeast also takes some finessing.  

  • The temperature must be between 21°C-24°C . It if is too cold the yeast will go to sleep and if it’s too warm they may just quit. The type of yeast that is being used determines the temperature range needed.
  • The brewer must ensure there is enough oxygen so the yeast can respire and create the fats they use as energy during the fermentation process.
  • Lastly, the yeast need the glucose and maltose, created during saccharification, which they will convert into alcohol and carbon dioxide.


Amazing transformation

With all the right conditions in place, it is amazing to watch yeast convert the sugars present in the wort and metabolize them into energy over and over again. During the metabolism process, as the sugar molecules are broken down, carbon dioxide molecules are released and ethanol molecules are created.


Where does the yeast go?

After the yeast has done its job, it falls to the bottom of the fermentation vessel leaving a layer of sediment. This gets left behind when the beer is transferred to the next vessel. Brewers also remove the yeast by clarifiying (using agents that bind to the yeast and cause them to fall out of suspension) or chilling (causes the yeast to go dormant and fall out of suspension).

Maybe you are not a fermentation geek like me but, I hope the next time you look into a glass of beer, you say a silent thank you to the fermentation process. For without it, there would be no beer.

Chelsea was an apprentice brewer at a microbrewery in New England. She is a former quality control technician at a large brewery. She has a bachelor degree in food science and she remains a dedicated home brewer. Follow her home brew brand, Lady Scotia Brewing for tips, tricks and any information related to home brewing.