Section 1 – Brewing with Malt Extract
Chapter 9 - Fermenting Your First Batch
So now you have the fruit of your labors cooled in the boiling pot and you feel like celebrating. But don’t call in your friends because it’s not beer yet. It won’t be beer until you have pitched your yeast, and the beer won’t be finished until it has completed fermenting, which is probably a couple weeks away at least. And then you will still need to bottle it... But have no fear, the hard part is over. What we need to do now is transfer it to your fermentor, make sure the wort has been aerated, pitch the yeast, and find a cool, quiet place to put the fermentor for the next couple weeks.
Choosing your Fermentor
Buckets vs. Carboys
There are three types of fermentor commonly available: food grade plastic buckets (bins) and jugs, glass carboys, and stainless steel buckets. Each type has its own merits. The plastic buckets are less expensive than the glass and stainless. The buckets (both plastic and stainless) have the outstanding option of being fitted with spigots, which makes siphoning unnecessary—a real plus. The buckets are typically 6 gallons, leaving 1 gallon of headspace for the fermentation, which is usually sufficient.
The spigot option eliminates siphoning between fermentors if you are racking to a secondary and simplifies bottle filling. A bucket with a spigot can be used as a bottling bucket, which allows better distribution of the priming sugar for bulk priming, and greater control of the fill level. Priming and bottling will be discussed in Chapter 11.
Although you will need a siphon, a glass carboy has the advantage of letting you see your beer and be able to gauge the activity of the fermentation. There are two sizes commonly available, a 6.5 gallon size that is perfect 5 gallon batches and a smaller 5 gallon size which is good for smaller batches. The large size typically has enough headspace to contain the krausen, so you can use it with an airlock instead of a blowoff tube. You will need to shield the carboys from direct sunlight (to avoid heating up), but you can easily tell when fermentation is over and the yeast is settling out.
Airlocks vs. Blowoffs
The decision to use an airlock or blowoff hose is determined by headspace. Usually the buckets and large carboys have enough headspace (at least 3 inches) that the foam does not enter the airlock. If the fermentation is so vigorous that the foam pops the airlock out of the lid, just rinse it out with sanitizer solution and wipe off the lid before replacing it. Contamination is not a big problem during the primary phase. With so much coming out of the fermentor, not much gets in. If the fermentation keeps filling the airlock with crud and popping it out, there is an alternative.
The alternative is called a blowoff hose/tube and it allows foam and hop remnants to be carried out of the fermentor. A blowoff is a necessity if you are using a 5 gallon carboy as your main fermentor, but it will likely result in the loss of a couple quarts of beer. Get a 1 inch diameter plastic hose and fit this snugly inside the mouth in the carboy or enlarge the hole in the bucket lid if necessary. Run the hose down the side and submerge the end in a bucket of sanitizer/water. Always use a large diameter hose to prevent clogging. If the tube gets clogged, the fermentor can get pressurized and blow goo all over the ceiling, or worse – burst. Blow-offs are sometimes necessary for 6.5 gallon carboys too, but there won’t be any beer loss, only the foam will be carried out.
Transferring Your Wort
Your wort should be cool before you pour it into the fermentor. If it is not, refer to Chapter 7 for suggested cooling methods. But before you transfer the wort to the fermentor, you may have been wondering what to do about all the hops and gunk in the bottom of the pot.
[figure 61 – pouring the wort]Figure 61—Pouring the wort into the fermentor. Aeration works best if it is poured back and forth a few times.
There will be a considerable amount of hot break, cold break, and hops in the bottom of the boiling pot after cooling. It is a good idea to remove the majority of the trub from the wort before fermenting. The hot and cold break consists of various proteins and fatty acids which are yeast nutrients, but there is usually more than enough in suspension to satisfy the yeast. (Various studies have demonstrated that turbid worts generally yield more vigorous fermentations than highly clarified worts.) The hops (depending on the amount in the recipe) tend to soak up a lot of wort, decreasing the amount of beer you get from your batch. So, there is a tradeoff between producing a clear wort for a clearer beer and providing nutrients to the yeast. If you are trying to make a very pale beer such as Pilsener style lager, the removal of most of the hot and cold break will make a significant difference.
The most common method for separating the wort from the break is to carefully decant the wort off into the fermentor, leaving the break behind. Pouring the wort through a stainless steel strainer can also help with this approach. If you are siphoning the cooled wort from the pot, then attaching a copper or stainless scrubby pad to the end of the siphon will help.
Whirlpooling will also help. Whirlpooling is a means of gathering most of the break and hops into the center of the pot to better enable the siphon to draw off clear wort from the side. Rapidly stir the wort in a circular manner. Continue stirring until all the liquid is moving and a whirlpool forms. Stop stirring and let the whirlpool slow down and settle for 10 minutes or so. The hops and trub will form a pile in the center of the pot, leaving the edge relatively clear. The siphon won’t clog as quickly now if it draws from the side of the pot.
[figure 62 – pouring the wort into fermentor, straining hops]Figure 62—Having poured most of the wort into the fermentor, I am now attempting to keep most of the trub out. After I throw the trub away, I will pour the wort back and forth to aerate it more.
But let’s get back to the job at hand, pouring the wort into the fermentor. 1. Pour the Water
Pour the reserved 2-3 gallons of water into the sanitized fermentor. Aeration of the water in the fermentor prior to adding the cooled wort is a good way to provide enough dissolved oxygen for the yeast. It is much easier to aerate this smaller volume of water first, rather than the entire volume later. 2. Pour the Wort
Pour the cooled wort into the fermentor, allowing vigorous churning and splashing. This provides additional dissolved oxygen that the yeast need. Try to prevent the majority of the hot and cold break from getting into the fermentor. Whole hops help to provide a filter. If some hops and break make it into the fermentor, it is not a big deal.3. Pour it Back
Discard the hops and trub from the brewpot and pour some wort from the fermentor back and forth to the brewpot several times. This will help ensure you have enough dissolved oxygen for the yeast. Short of using an airstone and air pump, this is the best way to aerate your wort.
Conducting Your Fermentation
Pitching the Yeast
[figure 63 – pitching yeast]4. Pitch
No, this doesn’t mean to throw the yeast out, it means to throw it in. Pitch (pour) the yeast into the fermentor, making sure to add it all. It is best (for the yeast) if the yeast temperature is same or colder than the wort temperature you are pitching to, and it is best for the beer if the wort temperature when you pitch is the same, or a couple degrees cooler, than the intended fermentation temperature. For ale yeasts, the fermentation temperature range is typically 65-75°F. Starting out warmer than your intended fermentation temperature will cause more off-flavors due to fermentation byproducts, and in extreme cases may cause the yeast to stall out as the fermentation cools down.5. Seal
Put the fermentor lid in place and seal it. But don’t put the airlock in quite yet; if you didn’t pour it back and forth earlier, we‘ll want to shake this up. Place a piece of clean plastic wrap over the hole in the lid and insert the stopper.[figure 64 – shaking the fermentor]6. Shake
With the fermentor lid tightly sealed, place it on the floor and rock it back and forth for several minutes to churn it up. This distributes the yeast into the wort and provides more dissolved oxygen for the yeast. If any wort leaks out, wipe it off with a paper towel that is wet with your sanitizer solution. Place the sanitized airlock and rubber stopper in the lid. The airlock should be filled to the line with sanitizer solution. Many people use vodka or plain boiled water as alternatives. You want something that will not grow mold or contaminate the batch in case it inadvertently gets sucked inside the fermentor.Note: If the fermentor starts out warm and then cools, you run the risk of the pressure difference sucking the sanitizer solution out of the airlock and into the fermentor. This will generally not be enough to kill the yeast, but it can cause off-flavors if you use bleach water.
Fermentation Location
Place the fermentor in a protected area that has a stable temperature between 65-75°F. Good places are closets, basements, or a spare bathroom if you have one. You will probably want to set the fermentor inside a shallow pan or put a towel under it in case any foam escapes through the airlock. Place it in an area that is not exposed to direct sunlight for two reasons. First, to keep it from getting too warm. Secondly, if you are using glass, sunlight will cause a photochemical reaction with the hop compounds and skunk your beer.
Maintain a consistent temperature if possible, because fluctuating temperature stresses the yeast and can impair the fermentation. If the temperature drops overnight and the bubbling stops, don’t worry, simply move it to a warmer room and it should pick up again. Temperatures below 60°F will cause ale yeast to go into hibernation and slow or stop the fermentation process.Animals and small children are fascinated by the smell and noises from the airlock, so keep them away. Dogs tend to like beer and will try to sneak samples before it’s done. Cats hate being left out of the decision-making during brewing and will attempt to get a paw in later. I also remember an acquaintance that was surprised when his fermentation started bubbling again after it had previously quieted. When he later opened the fermentor to bottle, he discovered his 3-year-old son had been dropping crayons and pencils in through the airlock hole.
Primary Fermentation
Active fermentation should start within 12 hours, but it can be longer due to lower pitching rates—about 24 hours. The airlock will bubble regularly. The fermentation activity can be vigorous or slow; either is fine. The three important factors for a successful fermentation are pitching enough yeast, good wort nutrients, and maintaining a consistent temperature in the correct range. If you do these right, it is not uncommon for an ale’s primary fermentation to be done in 48 hours. However, three days at 65-70°F for primary fermentation is more typical for most pale ales as described here. Once the bubbling slows down however, do not open the lid to peek. The beer is still susceptible to bacterial infections, particularly anaerobic ones like lactobacillus—found in your mouth. If you really want to look, peek in through the airlock hole, but keep the lid on.
Maturation
Fermentation and maturation actually happen concurrently. The yeast don’t finish one before starting the other. Plus, the yeast do not behave as a single group. There are literally billions of the little buggers all generally doing the same thing but at different stages of growth. However, if you have pitched enough yeast, the sugars will run out before the yeast all get tired, and this is why we consider maturation to be the final stage of fermentation. The primary food source is gone (sugars) but the byproducts (diacetyl and acetaldehyde) are still present and the yeast can finish those up. This maturation time probably takes a couple days, and just to be on the safe side, I suggest letting the beer rest for the same amount of time as it spent rapidly bubbling. This is why I recommend letting the beer sit in the fermenter for at least two weeks after yeast pitch before bottling. The attenuation may be done in the first week, but letting it sit the second week (still at the same temperature) ensures that the yeast have the time they may need to clean up the diacetyl and acetaldehyde, and also allows time for the majority of the yeast and haze to settle out and clarify the beer.
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Figure 60 - Fermentor diagrams during Primary Phase.
Figure 61 - Having poured most of the wort into the fermentor, I am now attempting to keep most of the trub out. After I throw the trub away, I will pour the wort back and forth to aerate it more.
Figure 62 - Pouring the wort back into the kettle. Aeration works best if it is poured back and forth a few times.
Figure 63 – Pitching the yeast. Yes, you can just sprinkle it on the surface of the wort. It will rehydrate and get busy. We used to recommend that the yeast be rehydrated and proofed before pitching (to make sure it was alive), but dry yeast is higher quality these days and doesn't suffer in packaging like it used to.
Figure 65 – Secure the lid and airlock and place in a cool consistent area.
Racking to a Secondary Fermentor
When should you rack to a secondary fermenter?
The answer is: when you plan on doing a secondary fermentation, such as on fruit.
Racking is the term for the process of transferring the beer without disturbing the sediment or exposing it to air. Usually this is done by siphoning. If you have a bucket fermentor with a spigot, then transfer becomes simple. It is imperative to not aerate the wort during transfer after fermentation. Any oxygen in the beer at this time will cause staling reactions that will become evident in the flavor of the beer within a couple weeks. Always start the transfer slowly and keep the outlet tube beneath the surface of the beer as you fill. Don’t let the stream guzzle or spray as you fill.
Historically (200 years ago or more), all fermentations were conducted open to the air. As the primary (attenuative) phase of fermentation would wind down and the protective krausen (yeast mass) would settle back into the beer, the beer could oxidize if left exposed to the air.
So, they transferred it to wooden casks or bottles where it would maturate and they could then condition it (i.e., add priming sugar for carbonation). Thus, maturation and conditioning became conflated with one another and was generally termed as secondary fermentation. Confusing, right?
Today, with our better understanding of how yeast work, we know that maturation is a yeast function, and the more active the yeast are, the quicker maturation will happen. Once the beer has maturated, it is ready to be bottled. If you are priming and bottle conditioning, then the beer will need another week or two to finish that, and then it will be ready to drink.
Beer generally doesn’t improve with age. If it is brewed right, it is best when it is fresh. Wine needs to age because it is very harsh when it has finished fermentation and needs time for the tannins to settle, fusel alcohols to esterify, and generally improve. Some strong beers can be stored for a long time, and while we talk about them gaining complexity from oxidation, in my opinion we are really just trying to be nice. Strong beers may age more gracefully, but they are still going stale.
Estimating the Alcohol Content
How much alcohol will there be? This is a common question. It can be measured in a laboratory, but it is difficult to predict precisely because there are several variables. There are several models in use so don’t be surprised if different brewing software give different answers.
The easiest way is to use a “triple scale hydrometer” which has a percent alcohol by volume scale right on it, although that is an estimate as well. If you don’t have this type of hydrometer, see Table 10, which is based on the work of Balling. Find the intersection of your OG and FG to read your estimated percentage alcohol by volume.
In the next chapter (10), we will discuss how the brewing and fermenting of lager beer differs from ales. Then we will prepare to prime, bottle and ultimately consume our beer in Chapter 11.
Table 10 - Estimated Alcohol by Volume from OG and FG
