By Chris Jennings
For the Oregon Beer Growler
The process of fermentation is a wondrous one. As brewers, we only have so much control over the outcome of a batch. Much of the work is done by yeast, and we simply strive to create an environment for that yeast to flourish. Besides adding a bunch of sugar for the yeast to metabolize, there is another ingredient that’s often overlooked on the homebrew level: oxygen. Yes, oxygen is bad in a finished beer, giving it a cardboard-like flavor. However, it’s crucial for the beginning of fermentation. Having the right amount of oxygen dissolved in your wort is going to noticeably affect the completed brew. The yeast will reproduce better, fermentation will be faster and the finished beer will be cleaner.
Now that you know that oxygen is beneficial, how do you get it into solution? The easiest and least invasive way to get oxygen into the wort is to either shake your fermenting vessel (not recommended with glass carboys) or by allowing the wort to splash as it flows into the fermenter. These methods are easy and cheap and it’s also next to impossible to get too much oxygen into the fermenter.
Another method involves an oxygen tank (available at some hardware stores) and a diffusion stone (available at most homebrew supply shops). The stone should be connected to a hose that comes off of the regulator on the oxygen tank. When the tank is opened, the tiny holes in the stone force oxygen into the batch. With a pure gas supply, there is the risk of over-oxygenating. If this happens, fermentation will be rapid but the yeast can stall and fail to clean up off flavors such as diacetyl and acetaldehyde — presenting the unwanted essence of buttery popcorn or green apple.
The amount of dissolved oxygen needed is approximately 1 part per million (ppm) for every degree plato. For instance, if you have a beer with a starting gravity of 1.065, your plato is 15.9, so you would need just under 16 ppm of oxygen. There are a handful of ways to measure dissolved oxygen in a solution. The most expensive method is a handheld electronic meter, which comes with a probe that’s inserted into the wort in order to extract oxygen and provide a reading. Unfortunately, this also removes oxygen from the batch, so if you try to obtain another reading from the same spot, the number will be lower.
Another, less-expensive option for measuring is a colorimetric test. This can be found at most aquarium supply stores and works like a chlorine test for a swimming pool. Simply add some wort to a vial, dilute it with water and then add a chemical that will turn the solution a different color (usually blue). Compare this shade to the provided chart and you’ll have a measurement. Of course, this won’t work well on dark beers.
The least-expensive way to measure is simply to experiment, which is what homebrewing is all about anyway! Start by adding small amounts of oxygen with each batch until you notice an improvement in your beer. Record the length of time you allowed the oxygen to bubble or how long you shook your fermenter and then make that a common practice. Once you’re in the right range, you’ll only need to take readings every couple of batches to ensure you’re still on track.
Nasal Blaster [AG]
Nasal Blaster [Extract]
By Chris Jennings
For the Oregon Beer Growler
Pushing the limits and finding new ways to tackle big problems is what drives many a passionate homebrewer. In the Pacific Northwest, a lot of innovation also revolves around the hop. Brewing huge IPAs can test our equipment and general knowledge about yeast. For instance, once you have that 1.095 starting gravity, getting the yeast to perform can be a challenge. Knowing how to approach common problems when making double IPAs will help you avoid a bad final product and possibly even create a great one.
Brewing Big IPAs
There are a few things to remember when crafting your own version of these big brews. As the name implies, you want to double everything: hops, malts and even yeast. If you’ve never made this style, you can simply start by doubling all of the ingredients in your favorite Northwest IPA recipe. Make sure you have enough grain or malt extract to hit a starting gravity of at least 1.065. Any starting gravity above 1.085 is considered “out of style.” Feel free to experiment. The mash will require a bit more water than normal to ensure a good extraction, so get a boil kettle that’s large enough to handle the extra volume.
When using extract, don’t exceed approximately 10 pounds for a 5-gallon batch. Non-fermentable sugars in the extract will add too much sweetness to the finished product. To make up any extra gravity, there’s no harm in using a small amount of sugar. This technique can also be used if you don’t quite hit the numbers you’re going for when brewing all grain. Add the sugar during the last five minutes of the boil to avoid caramelizing and stir frequently so that it doesn’t sink to the bottom of the pot and scorch. Due to the extra volume, boil for 90 minutes. That also provides 30 more minutes for hop additions. When timing this out, remember that anything incorporated in the first 45 minutes will significantly increase the bitterness of the beer.
Finessing the Yeast
Come yeast-pitching time, be sure you’re using a strain that will be able to tolerate the higher alcohol content you’re shooting for. This information should be available at your local homebrew supply shop. Additionally, it’s advisable to use two packets of yeast. The average yeast pitch has about 100 billion cells. According to yeast companies, this is sufficient for a 5-gallon batch with a starting gravity of 1.050, however, anything below 1.060 should lead to good fermentation.
The biggest problem with brewing higher-gravity beers is the yeast not doing its job. Make sure you help create a wort that’s the perfect, cozy home for those little yeasties to thrive and get to work. After your boil is complete, chill it quickly by using an ice bath or a chiller to avoid the production of dimethyl sulfide (DMS), a common off-flavor that can resemble the taste of cooked vegetables. It’s also important to ensure the yeast is the same temperature as the wort. Too much of a difference will cause the yeast cells to rupture. Take your yeast out of the refrigerator and allow it to warm up to room temperature. Before pitching, introduce oxygen to the wort to help get the yeast started.
Shaking the fermenter is adequate, but if you’re feeling adventurous, you can purchase an oxygenation assembly system that injects oxygen into the wort as it travels into the fermenter. You’ll also need a bottle of oxygen, which can be found at some hardware stores. Take care to not go overboard when adding oxygen.
Even after giving the yeast a fighting chance, it won’t always perform. In the event of stuck fermentation, when the yeast has gone dormant, there are still a few options. Adding more yeast to the fermenter is the quickest and easiest fix. However, the best time to do this would be before the wort has fermented at all because a later introduction could create off-flavors. If fermentation has gotten underway and then come to a halt, transfer the beer from the primary fermenter to a secondary. This will rouse some of the yeast and get the beer away from the dead yeast and protein.
Don’t focus solely on the activity in the air lock because many things can make it bubble. The only way to know whether fermenting has stopped prematurely or finished the way you’d planned is by taking a gravity reading. Even if you didn’t hit the numbers you’d hoped, the test of the tongue is, perhaps, most important. Only you can decided if your method needs adjustment or if you’re on the way to brewing an award-winning double IPA.
Jake's Wedding Imperial IPA [AG]
Jake's Wedding Imperial IPA [Extract]
By Chris Jennings
For the Oregon Beer Growler
During our homebrewing adventures, we encounter a vast new vocabulary that can seem like a foreign language to the average person. Being a homebrewer, however, means that we have an entirely new range of terms at our disposal. Often, a process or reaction that would’ve taken 10 words to describe can be summed up much more succinctly once you’re familiar with the jargon. One example of a new term you’ve likely stumbled across is attenuation. This describes the percentage of sugar the yeast will consume. Every yeast strain is different and many factors can affect how well the yeast performs.
Temperature is always very important to pay attention to during fermentation. As with each brew, every yeast has an optimal temperature range. Most strains perform best somewhere in the range of 65-72 degrees. There are, of course, exceptions. Belgians typically are at the warmer end of the spectrum whereas lagers need to be kept colder.
Temperature control is probably the most difficult challenge for brewers of every level. You can purchase fancy equipment to help with that, but if you don’t have those kinds of resources simply start by taking the air temperature of the room you plan to use for fermentation. Yeast will produce heat when it ferments, so as long as the room is about 5 degrees cooler than your ideal fermentation temperature, you will be on the right track. Whatever strain you’re using, make sure you’ve researched what temperature will provide an environment allowing it to perform at its best.
It’s in the Strain
All yeast strains have a temperature preference, but they also can be picky about the pH of the brew along with potential alcohol content. Be sure to do your homework on the beer style you plan to make. That will point you in the direction of the yeast strain you’ll want to use. There’s no need to rush out and purchase a pH meter or test strips. Instead, remember that darker beers are more acidic, so you want a strain that fits better with your grain bill.
Another factor to consider is gravity. If your starting gravity is too high, the yeast will have a hard time getting to work. It also may not ferment all of the potential sugars. Once again, research the individual strain to make sure, for example, the imperial wit you’re trying to produce will actually ferment completely. Most every yeast strain will indicate what style of beer it fits with by its name alone. However, some types of yeast can perform outside of the normal style guidelines.
Experimentation can be an exciting way to find these anomalies, but thorough research will help ensure that your finished product turns into the tasty homebrew you were shooting for.
Ale Gating [AG]
Ale Gating [Extract]
Stories from the print edition of the Oregon Beer Growler.