Bad Lagers, Big Blowoffs & Barrel Use: Mr. Wizard
Q
My lagers always contain a lot of sulfur and vegetative (like garbage or rotting vegetation) aromas that overpower the beer. My lager boils are typically 75 minutes, full rolling boil uncovered with overhead vent fan using gas plus electric heat stick augmentation. I use both liquid with stirred starters and dry yeast (all style-appropriate lager yeasts), all scaled to appropriate pitching rates using the calculator at mrmalty.com, and all ultimately giving the same sulfury vegetative results. Typically I chill to 50 °F (10 °C) and pitch. Then I ferment around 52 °F (11°C) +/- 1 °F/°C in a dedicated ferment chamber with external temperature control, proxy thermo-well in a separate jug of water, and forced air convection until fermentation slows, and a sample shows about 65-75% complete. Then I raise the temperature over a couple days to about 65 °F 18 °C and let it sit for a while. I have read over and over that a warmer fermentation at the end helps scrub sulfur and absorb diacetyl. My diacetyl is getting cleaned up, but not the sulfur or vegetables.
Francisco Jones
Kankakee Illinois
A
Francisco, nothing in your description of your lager brewing throws up any warning flags related to sulfur production. It really sounds like you are doing a very good job with yeast pitching control and fermentation temperature control. The Mr. Malty yeast calculator is a nice tool and is fairly conservative, so I do not think your problem is yeast pitching rate, the root cause of many fermentation off-flavors.
Another key factor related to fermentation-related aromas is yeast strain. It is certainly true with lager yeasts that some strains do indeed produce more sulfur aromas than others. I have used several lager strains over the past 16 years at Springfield Brewing Company and settled on the Augustiner lager strain a couple of years ago and have been very happy with the results. One of the aromas I wanted to minimize in our lagers was hydrogen sulfide, which smells like a rotten egg. The Augustiner strain does produce sulfur during fermentation, but it dissipates in our process to yield very clean lagers.
For what it is worth, we cool our wort to 50 °F (10 °C) and ferment at 54 °F (12 °C). We use a spunding valve, a type of pressure relief valve commonly used to capture carbon dioxide in fermentation vessels, and the valve is put on the fermenter when we are about 1 °Plato above our projected terminal gravity. The beer is held at fermentation temperature for 4 days after spunding for diacetyl reduction. We then chill the beer to 38 °F (4 °C) and hold at this temperature for about 10 days. The lager yeast is still active at this temperature and diacetyl and acetaldehyde reduction continues during this time period. The beer is then cooled to 30 °F (-1°C) for at least 2 days before filtration or racking in the case of unfiltered lagers.
Like many brewers, I have some rituals that are based on a mixture of tradition, practical experience and science. What we do works for us, so we are not real keen on changing things. We cannot raise our temperature for a diacetyl rest, so we use a longer rest period to achieve our goals. I know from pulling samples during lagering that the sulfur profile of our lagers does significantly change during the time from spunding to serving. I have always believed that the slow, continuous release of carbon dioxide from the spunding valve during lagering helps scrub sulfur from the aging lager. One confirmation of this scrubbing is the aroma released from the valve; at the early stages of lagering the sulfur intensity is greater than it is towards the end. If you simply complete fermentation and keg or bottle your lager without this gas scrubbing process there is no mechanism for sulfur removal since yeast does not absorb these compounds as is the case with diacetyl and acetaldehyde. Homebrewers who keg their beer can scrub sulfur compounds by bubbling carbon dioxide into the beer from the spear, then slowly releasing the head pressure, and repeating the process several times. This not only will help to scrub sulfur aromas out of the beer, it is also part of the force carbonation process.
The aromas you describe could be associated with very high levels of dimethyl sulfide. It sounds like you have a very good boil, but if you do not quickly cool wort after boiling, residual S-methylmethionine (also called DMS precursor or DMS-P) will be converted in the hot wort to DMS. In the absence of boiling and steam stripping, the DMS will remain in your wort and can show up as a flavor defect in the finished beer. Most brewers using some sort of wort chiller to cool the wort fairly quickly after boiling do not have this particular problem. My gut feeling is that DMS is not your problem.
Two other things to consider are yeast nutrients and sanitation. While all-malt beers typically contain plenty of amino acids and phosphates, they can be deficient in zinc. Some yeast nutrients, especially types common to winemaking, are mainly comprised of amino acids and phosphates, and other nutrients are really designed to boost zinc levels in wort. We use Servomyces in all of our beers and I believe that this really helps us with producing very clean beers. This product is sold by White Labs and is a good source of zinc. Remember that aeration is important because oxygen is also a sort of nutrient and is integral to the synthesis of membranes during cell growth. Finally, poor sanitation can lead to microbiological issues that certainly can cause terrible off-flavors associated with bacterial contamination. Hopefully I have touched on something to help you produce better lager beers!
Q
Does having two airlock blowouts during the first 12 hours of fermenting mean a bad batch?
Nate Tolvaisa
Havertown, Pennsylvania
A
In the commercial world of brewing, one of the biggest fears is a fermentation that is slow to start or one that lacks vigor when it does come to life. These traits foreshadow problems lurking on the horizon. Any microbiological critters coming forward into the fermenter from wort production or bacteria associated with pitching yeast are much more likely to take hold in a fermenting batch of beer if fermentation does not take off quickly and with command of the situation. Alcohol production, pH reduction and oxygen consumption all occur in the early stages of fermentation and collectively help to build a hurdle for bacterial takeover. The combination of inhibitory factors is indeed known as the hurdle theory by those who study food microbiology. The more hurdles put before unwanted organisms reduces their ability to colonize the environment. In the world of beer, decreased pH, alcohol, reduced oxygen and the competitive nature of a healthy yeast population make it rough on unwanted guests, like spoilage bacteria and yeast. The opposite of this is true when funky, sour beers are being produced. Too many hurdles, especially hop bitterness, reduces the chances of being successful with these funky brews.
So blowing off your airlock is not a bad thing because it is an indicator of a healthy fermentation. But blowing your airlock is really not the best thing for your beer, your carboy or your home. Airlocks help protect your beer from the environment outside of the fermenter. When it launches from the top of the carboy you are no longer protected. Airlocks can become clogged and fail to launch like a missile from the carboy and this can cause carboys to break. When an airlock launches from the carboy foam may follow and when a carboy breaks beer is sure to follow. Both of these things are bad for the home. The take home message is that blowing off your air-lock should be avoided if at all possible.
Another problem associated with blowing off “stuff” during fermentation is loss, since beer is a major component of this “stuff.” Commercial brewers typically have 25-35% headspace volume in fermentation vessels to minimize or completely eliminate blow off during fermentation. The take-home message is to consider using a 6-gallon (23-L) carboy for your 4- to 5-gallon (15- to 19-L) batches.
The best thing to attach to your primary fermenter is a blow-off hose that allows for a large volume of carbon dioxide and foam to escape the fermenter while preventing the formation of pressure that can cause the problems described above. All commercial breweries, ranging in size from the smallest to the largest, use some sort of device to allow gas and liquid to flow out of the fermentation vessel because this sort of problem can grow from a small-scale nuisance to a large-scale disaster.
The good news to report is the health of your fermentation seems to be excellent! I think future batches will be improved by the use of a blow-off tube better able to handle the active nature of your fermentation.
Q
I’m about to put a golden strong ale in a barrel. I’ve been told different things on both the cleaning of the barrel and how long to leave it in the barrel. First, should I use Star San in the barrel? And how long should I use a barrel for the secondary fermentation?
Johnny Hill
Louisville, Kentucky
A
Barrel aging is really a fun thing to do because it brings flavors and aromas to beer that are simply unachievable using other methods. New barrels can be used to introduce vanilla and toasted notes to beer. Oak spirals and chips can be used for similar flavors, but barrels do more than add oak flavor. As beer ages in oak it slowly oxidizes due to the ingress of oxygen through the porous structure of the staves. This is one of the reason that microaerophilic organisms such as Brettanomyces species, Lactobacillus species, and Pediococcus species grow relatively well in barrels. It is also the reason why brewers and vintners are concerned about using used barrels if the idea is not to make funky beer or funky wine, which really has failed to become as popular as funky beer. OK, funky wine is totally unacceptable, but I digress.
Whether starting out with new or used barrels, there are a few things you can do to help ensure a positive barrel aging experience. With a new barrel you can tackle two concerns at once by filling the barrel with nearly boiling water to sterilize the surface of the barrel and hydrate the wood and help the barrel seal before use. Since wood is a good insulator the water will stay hot for several hours. I typically leave new barrels filled with water for about 6 hours and then empty the barrel by syphoning the water to the floor. Allowing the water to cool to about 140 °F (60 °C) makes this process a little less steamy. After the barrel is empty you can go ahead and rack your beer into the barrel.
If you have a used barrel the chances of having microorganisms inside of the barrel are much more likely than starting with a new barrel. It is common to clean barrels by rinsing with cold water, then warm water and finally hot water after use to remove the different types of soils that are deposited in the barrel during use. It is not uncommon to use a mild cleaner, such as sodium carbonate, after the barrel has been thoroughly flushed with water. After cleaning and drying, elemental sulfur sticks can be burned and sealed in the barrel to create a sulfur dioxide fog that suppresses the growth of organisms. This process needs to be repeated about once every four weeks to preserve the integrity of the barrel. Using other types of sanitizers is not common with the use of barrels. I would not recommend using products like Star San unless you can find references that indicate otherwise.
When it comes to barrel aging, the duration of aging depends on several factors. If you use a barrel that previously contained another product and your intent is to flavor your beer with this product you may find that little time is required. I have barrel aged stout in 8-gallon (30-L) whiskey barrels for 4 weeks and ended up with some really stellar products. I have also aged beer in new oak barrels for a few months and have extracted more vanilla flavors than I really wanted. On the other extreme I have aged beer in barrels with Brettanomyces and have had to wait more than a year to achieve the results I wanted.
One interesting side note about using bourbon and scotch barrels is the subject of bacteria. It seems that these barrels would not be vectors for contaminants. Mitch Steele, Head Brewer of Stone Brewing Company, noted that they have actually found this assumption to be false and that used bourbon and scotch barrels can harbor bacteria. The likely reason for this is that these barrels are emptied somewhere, certainly not very near San Diego, stored, shipped and then used. During this time the interior surface of the barrel is exposed to air. Since the charred surface of whiskey barrels is porous, it is a good environment for bacteria to colonize.
When putting beer in a barrel you should consider drilling a small hole in the lower portion of one of the heads and plugging the hole with a stainless steel nail. The nail can be removed to pull a sample. This will help minimize damage to your beer from sampling with a thief. This is especially true if the beer has a Brettanomyces pellicle that helps protect the surface from oxygen and subsequent colonization by Acetobacter, which converts ethanol into acetic acid (vinegar). The other thing I strongly recommend is to be patient. If you sample the barrel and do not taste what you desire, wait at least a month for sampling again. Excessive sampling simply reduces the batch size.
