The Science Behind Beer

BY JAKE M C RAE

Many of us like to enjoy a nice cold beer from time to time. But have you ever wondered about what goes into making this popular beverage? In this article I will cover the basics of how beer is made, mostly focusing on the process of homebrewing, though it is usually a similar process industrially, just usually done with more efficient equipment and perhaps more refined techniques. Also note that this article is not meant to be a how-to guide for homebrewing beer, rather it is intended to give you an idea of the science and the process behind beer. Additionally, beer comes in many types and not all of the processes are exactly the same, so I will cover the most general process in this discussion. I’ll also try to highlight some of the specific terms used throughout the process. Also, a big part of this process is making sure every tool used is sanitized. If the beer has any unwanted elements during the fermentation process, it may become infected, and the batch will be ruined (1). There are several pieces of equipment and ingredients required to brew, and there are varying degrees of specialization when it comes to equipment. Most fundamentally, as a homebrewer, one would need: grain (barley, wheat, oats and/or rye), yeast, hops, water, a large glass jug or fermentation tank, a couple of large pots, a strainer, an airlock, plastic tubing with some adapters, and bottles.

The first step in brewing is malting. During this stage the grain, which is mostly barley, is prepared and readied for brewing. This starts with soaking the grain in water so that it can germinate. This germination begins the breaking down of the starches. (2) Then the grain is dried out, and sometimes roasted. The temperature at which this drying/ roasting occurs will determine what type of malt the beer will be. Higher temperatures will produce a darker malt, and lower temperatures a light malt. This can impact the eventual color and flavor of the beer (3). Once dried, the grain is milled or ground to crack open the grain husks and make the starches more accessible (4). These steps are typically done at the industrial scale, and homebrewers usually buy their grains already milled and prepared. At this point the grain is referred to as the grist (4).

The next stage is mashing, where the starches in the grain are broken down into sugars, which will ultimately be turned into alcohol. Here, the grist is mixed with water heated to around 140 degrees Fahrenheit (give or take 30 degrees, depending on the specifics of the beer) for 1-2 hours (4). During this time the hot water activates the enzymes (proteins which increase the speed of chemical reactions) which con- vert the starches into sugar in a process called saccharification (3). Variations in the temperature during this time can impact the final product, making this a place where brewers can specialize their beer (4). The resulting sugar and water combination is referred to as wort.

Next is sparging, a process where the wort and additional water are filtered through the grains to extract the last of the sugars. To begin sparging, the temperature of the wort is raised to around 170 degrees Fahrenheit, which stops the enzymes and preserves the fermentable sugars. This is called the mashout (4). Then the wort is transferred into a separate vessel and the grains are placed in a strainer or lauter tub. The brewer will then proceed to sparge by running the wort and some additional heated water through the grains several times until the grain has had all of the sugar and flavor removed from it (4). The spent grain is now used up and will play no further role in the brewing process. However, the grain can still be used for feeding farm animals, composting, growing mushrooms, or even baking bread.(5). Now that the wort has become saturated with sugars, it is time for the boil. During this step the wort is heated to a rolling boil which stops any enzyme activity and condenses the wort (4). This is the time when brewers add in hops, which change the flavor, adding in bitterness and aroma while balancing out the sweetness of the malt (2). Hops can determine what type of beer the final product will be. The boiling is necessary to extract the bitter resins from the hops so that they can be combined with the wort. If the hops are added earlier in the boiling, the beer will be more bitter (3).

After the boil, the wort needs to be cooled so that when the yeast is added, or pitched, it will not be killed by the high temperatures. Sometimes before cooling there is an additional stage where the wort is spun or whirlpooled to add in more flavoring elements and to filter out some of the sediment from the hops and perhaps the grist, which is called the trub. The cooling can be done several ways. The simplest is to place the pot into an ice bath until its temperature reaches about 70 degrees Fahrenheit (6). Cooling can also be done with a heat exchanger which transfers the heat from the wort to some other water, sometimes then used for another batch of beer (2).

Now we are getting to the most important stage: fermentation. Here the yeast is pitched after the wort is transferred to the vessel, usually a large glass jug or a fermentation tank, where it will stay during the fermenting process. The yeast eats the sugars, transforming them into carbon dioxide and ethanol. This gives the beer some of its carbonation and makes it alcoholic (3). After pitching the yeast, the beer is stored for at least a week, but sometimes for a few months, in a dark, room temperature location. During this time yeast eats through the sugars and comes to settle as trub, at the bottom of the fermenting vessel. The vessel needs to be sealed with an airlock, which prevents anything from getting but allows the carbon dioxide to escape (6). Sometimes brewers will have the beer undergo a secondary fermentation to further alter the taste, carbonation, and/or alcohol content (3).

After the fermentation, it is almost done and now it is time to bottle the beer. This is usually done by siphoning the beer from the fermentation vessel. It is siphoned rather than poured so that additional oxygen is not introduced and so the trub, which is only waste at this point, does not get into the final beer. It is then transferred into bottles and given some final carbonation in one of two ways. Either this is done through a forced carbonation process, which involves adding carbon dioxide under high pressure. This technique is much faster and the beer is now ready for distribution, but requires specialized equipment (4). The simpler but slower method is to add a little additional sugar (often honey or maple syrup for extra flavor) or yeast. The beer then has to sit in the bottles (also in a dark and room temperature environment) for about a week, and then it is ready for drinking. With this method you have to be careful not to let it sit for too long, because it may become overcarbonated. Once it is ready, it can be transferred to a fridge which prevents any further carbonation (6).

At this point the beer is ready to be enjoyed. Though this process is a lot more laborious than just buying some beer from the store, it can be rewarding and fun to explore the process and get to enjoy a drink that you made yourself.