College students are familiar with beer--what it is, what it tastes like, and its effects if you drink enough of it. However, few people actually know how beer is brewed or what ingredients go into producing it. For my Microbiology Lab course at University of California, Irvine, my lab partner and I had the opportunity to brew beer for the first time and select from a variety of ingredients. Being a science major and a foodie, I appreciate when biology concepts from my courses connect to practical applications of food and drinks. This is something you can easily replicate at home and can even be done on a larger scale (2 gallons!) if you decide to use a complete beer making kit. Here are the steps we took to make our beer:
The 3 Main Ingredients:
Dried Malt Extract, Hops, and Dry Yeast
Step 1: Malting (or Mashing) and Brewing
Yeast is responsible for fermenting the beer by breaking down simple sugars from barley. The barley grains are soaked in water and heated to break down complex starch molecules into smaller sugars like maltose that the yeast can ferment into alcohol. This produces a wort, which is dried through a kilning process that stops the reactions and helps to preserve the beer.
But do yourself a favor and skip this malting procedure by using a dried malt extract. We chose Extra Light malt extract, but you can choose from a variety, including Extra Dark, Wheat, and Amber.
In a medium stove pot, boil 1 cup of water and add about 70 grams of your malt extract. Continuously heat and stir the mixture for 45 minutes, adding water when some of it has visibly evaporated. We were limited to doing this with our lab equipment.
Step 2: Boil with hops
The next ingredient to add to your boiling wort is hops, the flowers of the hop plant. Hops balance out the sweetness of the malt because they are composed of alpha acids that impart the bitter taste of beer. They are also a natural preserving agent.
The earlier you add hops, the less bitter your beer will be, but make sure to add it while still boiling. Boiling sterilizes and concentrates your wort. There are many different types of hops, but we decided to use Centennial Hop Pellets, which have a strong citrus aroma and floral tones that pair well with ales and IPAs.
Mix in 1.5 grams of hops into the wort and continue to boil with stirring for about 15 minutes. Then, add about 1 more cup of water and take the extract off the heat, letting it cool to room temperature.
Step 3: Allow your beer to ferment
Your extract can now be transferred into a bottle and aerated by inverting it 15 to 20 times for good measure. Dry or liquid yeast is added at this time to start the fermentation, the process that will finally yield alcohol! After utilizing all the oxygen in the bottle to grow, the yeast will metabolize the malt sugars into carbon dioxide and and ethanol.
We selected Munton's Premium Gold, an ale yeast that ferments at room temperature and has a more fruity taste. Lager yeast ferments better at cold temperatures, takes longer to ferment, and is associated with a clean or crisp taste. Add approximately 1 teaspoon of your chosen yeast into the bottled extract and let it ferment at room temperature for two weeks.
The hard work is over, and now you just have to wait.
Step 4: Add a priming sugar and bottle
At the end of 2-3 weeks, the yeast cells and other waste products have sunk to the bottom of the bottle. You can now filter the beer, leaving the bottom debris behind, and transfer it into a new bottle.
The last thing you will need to add is a sugar solution. The sugar will be converted into carbon dioxide, which carbonates your beer and makes it refreshing and bubbly. We had 5 milliliters of a sucrose solution, which translates to about 1.65 grams of sugar dissolved into 1/2 teaspoon of water.
The lid of the bottle must be sealed completely in order for the beer to become carbonated, and you can ensure a tight seal by using a bottle capper.
Step 5: Refrigerate and serve
After letting your beer sit at room temperature for one more week, you can finally refrigerate and drink it!
You may love the final product or the taste may not be what you expected, but at least you can call yourself a craft beer brewer. An amateur one at best--but the beauty of this experiment is that you can attempt it again and tweak some of the three main ingredients so your beer can taste even better the next time. Remember to have fun and drink responsibly!
Thank you to Dr. Brian Sato, Professor in the Department of Molecular Biology and Biochemistry at the UC Irvine, for this awesome and unique learning opportunity. Also, thank you to Kristin, for being a great TA, and Jasmina, for being the best lab partner.