By Anthony St. Clair
For the Oregon Beer Growler
Wrangling yeast can be as easy as moving it from one fermenter to another. Unless you have four yeast strains in regular use and a tight production schedule that can’t always wait for the yeast to be ready. That’s why, earlier this year, Eugene-based Ninkasi Brewing Company brought online a dedicated system of yeast propagation and storage tanks.
“Yeast is the only raw ingredient we supply ourselves,” says Dr. Daniel Sharp, director of brewing process development. “In addition to beer, we also make yeast, so having dedicated vessels for making and storing yeast is no-brainer, especially due to the amount of beer we make and how many yeast strains we use.”
Originally championed by Ninkasi’s in-house lab and quality control teams, the propagation system (“prop” for short) arrived earlier this year. “Before having this system, we were all doing this with our current brewing and tank setup, trying to fit it in and make it work,” says Sharp, “but that’s challenging when you have all your fermentation vessels full. But you need vessels to make yeast to make more beer. It was an easy ROI, and it makes yeast production easier for the whole team.”
The custom-made system was fabricated by W.M. Sprinkman, a dairy, food and beverage equipment manufacturer in Wisconsin. The system is comprised of three 10-barrel brinks and one 5-barrel brink for storage as well as 20- and 30-barrel props. Controls include gravity, gas composition (vessel atmosphere), agitators to aid cooling and homogeneity, and temperature. For oxygen, “we used to use a standard dosing rate, like most brewers, added at the beginning of fermentation,” says Sharp. “Now we can add oxygen based solely on how much the yeast needs to grow, instead of how much it needs to ferment. We’re still working with it to figure out the optimal amounts, but playing with the oxygen levels for the yeast is helping us grow healthy yeast faster.”
A positive displacement pump, great for moving thick liquids while being gentle on the yeasts, is used for transfers. After yeast is grown in the lab, it’s added to the prop and then pitched into wort during knockout. One 30-barrel batch of yeast can pitch a full 550-barrel fermenter. Instead of pitching by volume, the tanks are connected to load cells, so Ninkasi’s brewers know how much yeast is being pitched down to the pound. “We also don’t like to waste things, especially yeast,” says Sharp. “Nailing in exactly the amount we need when we need it, that’s the goal.”
Installed and tested during March and April, Ninkasi uses the system for the full yeast propagation process. The benefits have been immediate. Yeast propagation used to take 14–21 days. Now it can be done in 10–12 days.
“The shorter time helps us be flexible and work with the yeast while it’s in a happy state,” explains Sharp, “while also working with the other needs of the production schedule. We look out weeks in advance, and the shorter time is a big win.”
Parallel environments ensure optimal conditions for both beer and yeast. “Fermentations are great for making alcohol but aren’t good conditions for yeast growth,” says Sharp. “The conditions for growing yeast are bad for beer, such as needing oxygen. With the props we can grow a healthy supply of our own yeast without compromising beer flavor. Also, by controlling the conditions of our yeast growth and health, we can better control the subsequent fermentation profiles.”
Depending on the schedule, now yeast can be taken straight from one fermenter to another, or it can be stored in a brink and used for up to 10 fermentations. With four strains in regular use (Helles Lager, English Ale, Chico Ale and German Ale), plus a house yeast library for special projects, it’s also easier to maintain the “yeast pipeline” so that yeast is at an optimal state for pitching. For example, the English Ale strain — used in flagship beers such as Total Domination IPA — is a “juggernaut” that has adapted well to Ninkasi’s brewery and higher-IBU and ABV beers, while providing softer blending aromas and flavors.
“We don’t do delicate yeasts that need coddling,” says Sharp. “We need tough yeasts.”
On the flipside, for a beer such as Hop Cooler IPA, the Chico Ale accentuates individual characteristics, and the German Ale yeast used in Sleigh’r Dark Double Alt Ale is less flocculent, so some residual yeast remains for a thicker mouthfeel.
“We are a yeast farming facility that makes good beer,” says Sharp. “Our job is to make good yeast, or we can’t make good beer.”
By Chris Jennings
For the Oregon Beer Growler
As homebrewers, it seems as though we face a nearly unlimited amount of choices for every detail in making beer: whole hop or pellet, all grain or extract, liquid malt extract or dry malt extract. The list goes on and on. For the most part, there are only subtle differences in the results with most of these factors. However, the decision to go with either liquid yeast or dry yeast can not only change the outcome of your brew; it also will affect the entire process.
Finding Substitute Yeast Strains
Whether you’re using a recipe you spotted online or discovered it in a dusty tome in the basement of a library, there’s a good chance either way that it calls for yeast. Most directions are also very specific about what brand and strain of yeast must be used as well. Deviating from the plan will not yield optimal results, according to the author of the recipe. But at times, there are some yeast varieties that simply aren’t available. Either the company has disappeared or the strain is a seasonal release, so finding a suitable substitute can be a challenge. Of course, every challenge is just an opportunity to discover something new and amazing.
There are some yeast strains that are so similar, either liquid or dry, you won’t notice any difference. Therefore, if your recipe calls for White Labs WLP001 California Ale Yeast and your go-to homebrew shop is out, you can try the dry Safale US-05 from Fermentis. But things get a little trickier when your desired strain is no longer in production or only available seasonally. The best thing to do in this situation is to research as much about the yeast as possible and then compare it to what’s available. That information will allow you to make an educated guess about what will serve as an adequate substitute. You could also just select a completely different strain all together and create a new tasty variation. When selecting a new strain, there will be more options from all of the liquid yeast companies. Though there are some crossovers, keep in mind that the liquid companies have unique strains that are hard to substitute.
The most obvious difference between liquid and dry yeast is that one is stored in a fridge and in a liquid state while the other is vacuum-sealed on a shelf. The liquid yeast is branded as “fresh” because it is raw and has a shelf life. The liquid yeast needs to be stored in a cold place to preserve that freshness. However, dry yeast has been freeze-dried and resembles baker’s yeast. It should be stored in a room with low humidity. While dry yeast will last much longer than liquid yeast, it also does have an expiration date.
There are advantages and disadvantages to both dry and liquid yeast. Storing dry yeast is much easier. But liquid offers more variety. At the end of the day, homebrewers have many options, which just makes your next beer-making adventure even more exciting.
Holly Day Ale [AG]
Holly Day Ale [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]
By Chris Jennings
For the Oregon Beer Growler
Now that the new year is upon us, we should make some beer resolutions to continue to enhance our brewing skills. No recipe is complete without the perfect yeast, but what happens if the yeast that we love doesn’t get produced again? Not only can we as homebrewers harvest yeast from bottles and the world around us; we can also save a few dollars by keeping our favorite strain going for several yeast generations.
After your tasty homebrew’s primary fermentation period, the yeast will fall to the bottom of the fermenter and form a cake. Usually we would just discard this cake, but it‘s still a viable yeast pitch. As long as you were careful not to introduce anything foreign into it, you can use the cake as a new pitch for your next brew. The fastest and easiest way to reuse the cake is to brew the same day you empty your fermenter, then just put the new wort into the bucket with the yeast. You can only use this method a few times before you may notice some off-flavors beginning to develop. This is because there is protein and even some beer left from the previous brew. If you are planning to use this strain for much longer than a few brews, you can wash the yeast.
In order to wash the yeast, put about 3 gallons of cold water into your fermenter. Transfer as much of the sludge into a glass carboy or other clear vessel. Make sure there is plenty of liquid and that most of the sludge is stirred into the solution. You need to then put the carboy into a chilled area around 50 F. This will force the proteins and dead yeast cells to fall back into the cake and should only take a few minutes. Once most of the cake has re-formed, the live yeast cells will be floating in the water, so rack the water with the living cells into a separate sanitized container. After this is complete, you have a fresh yeast pitch with minimal impurities. You can continue to wash the same strain of yeast for several generations with very low levels of flavor change. Eventually the yeast will mutate and it may take on a completely new flavor. As long as it still tastes good, there’s no reason to stop using it when it can save you money.
Capturing New Strains
Purchasing yeast at your local homebrew shop is the safest guaranteed way to get the flavors that you are looking for in your homebrew. But sometimes you can harvest yeast out of an empty beer bottle and have your very own Duvel strain. If you are going to attempt this, you need to be sure that the beer has not been filtered or pasteurized. When you have found the beer with the yeast that you want, decant as much of the beer out of the bottle as possible. Add some cold water and transfer the remaining contents of the bottle into a flask or growler to begin making a starter.
To make a starter, cook up a small amount of wort by using dry malt extract and boil it with some water. Once the wort is chilled, add it to your flask or growler and allow it to begin fermentation. Be sure to incorporate air into the solution as well because it will help the yeast grow. You can do this by swirling the container every few hours or every time you walk past it. Another option would be to use a stir plate with a stir bar like the kind you might remember from high school chemistry class. Either way, in a few days your yeast should have enough cell growth for you to pitch it into your next tasty experiment.
Though it is cost-effective to save yeast and begin your own yeast bank, it can be a daunting task. Starting small and getting a few of the different techniques mastered can help to start the new year off right and ensure a successful brew year.
Killer Winter White [Extract]
Killer Winter White [AG]
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