Debunking Bitterness, Mystery Fermentation, No Chill Brewing
Q
I recently saw an IPA recipe from Jamil Zainasheff that listed the IBUs at 100. Is this in the realistically attainable range on a basic homebrew setup (full volume boil pot and mash tun only) with “normal” hops/hop products (whole leaf, pellets or plugs)? I recall reading somewhere that 80–85 IBUs was the max without special equipment.
Mike Killgore
Beaverton, Oregon
A
The limit of beer bitterness is really a function of the solubility of iso-alpha-acids in wort and their survival into finished beer. Most of the literature on this topic is of the practical sort where data showing the IBU level of various commercial beer is part of the discussion. Hypothetical discussions that focus on everything but real beer makes me a little grumpy. Brewing beer with 100 IBUs is certainly within the realm of reality based on beer that is brewed and commercially sold.
It is true that there is not a singular “Max IBU” value that is applicable to all beer because wort pH and wort gravity directly affect hop isomerization during the boil. Furthermore, what happens during fermentation, aging and filtration (for brewers who filter) influences hop utilization. If
you are attempting to get the maximum bitterness level and are limited by iso-alpha-acid solubility in wort, then it logically follows that downstream iso-alpha-acid loss will reduce beer bitterness. Loss occurs when trub sticks to fermenter walls, foam is skimmed from fermenters, bitter acids adhere to yeast cells and when beer is filtered.
I am not sure what special equipment is required to brew high IBU beers. Wort loss can become a real issue, so this may be what you have read. Commercial brewers brewing some of these monsters often launch an über-bitter beer as a special and are not overly concerned about efficiency. But then the special sticks and their consumers want more. And then efficiency becomes a real concern because excessive wort loss is an expensive proposition when operating a brewery with the intent of making money. Very broad whirlpools are one solution to deal with high hop loads in the brewhouse if pellet hops are used. If cone hops are used things are a bit easier since the hops are typically removed with a hop separator before the whirlpool. So there are some practical concerns related to hop removal when brewing beers with big hop additions.
The bottom line with this question is that you are correct to be asking about limits, because they do exist when it comes to bitterness. I am a very skeptical consumer when it comes to putting much faith in certain claims, especially the claims of small packaging breweries, pub brewers and homebrewers. The reason for my skepticism is simple; claims without lab analyses equal estimates. And most small brewers do not have the laboratory equipment required to perform IBU analyses. Couple this with the sometimes tremendous testosterone flow present when brewers brag about the big size of their latest imperial this or that and the result is often exaggeration.
The limit of beer bitterness is really a function of the solubility of iso-alpha-acids in wort and their survival into finished beer.
I am a simple brewer and simple beer consumer with a unified philosophy about brewing. Rule number one; it’s all about perception. If what we do in the brewery cannot be perceived by the consumer or does not influence efficiency then why worry about it? Some brewers advertise that they lager for eight weeks, or whatever. That’s cool, but does the beer taste better than beer aged for six weeks, five weeks or four weeks? If it does, then there is a compelling reason to age for eight, but if the only reason is to talk about it in marketing I am not the type of brewer who would agree with the decision. Rule number one has a few caveats. For starters, I am not referring to ingredients in beer that can cause bodily harm without being detected when drinking; these are still perceived, just not immediately. I am also not referring to cleaning and maintaining the brewery environment. My rule number one is really about brewing process decisions.
Rule number two; limit brewery speak when communicating with consumers. People do not consume laboratory results, they consume beer (in the context of this discussion). Lab-oratory numbers taken out of context really give very little information about flavor. We may assume that beer with a meager 50 IBUs is less bitter than another with 80 IBUs, but perceived bitterness has much to do with the beer itself. Alcohol content, residual extract and malt selection all influence bitterness and IBU values alone do not define perceived bitterness. Some brewers and beer writers share the opinion that beer consumers are often turned off by this “geek speak” because it has the effect of alienating people who may really like beer, yet know little or nothing about the process.
Q
I brewed A Founder’s Breakfast Stout clone from BYO, added some extra grain and my OG was 1.090. It was my first beer with coffee, chocolate and cocoa nibs. I pitched half of the batch with some S-05 yeast harvested from a recent batch of porter and pitched the other half with fresh S-04 as an experiment. I brewed the stout on Sunday, and on Monday when I got home there was only a bit of foam (it was oily looking) on top of the beer but no real kräusen and there were no bubbles coming out unless I shook the carboy. After about three days of shaking, I couldn’t get any more bubbles to come out from shaking. Thinking I did something to kill my yeast, I added extra yeast (S-05 to both). I kept watching and saw no signs of fermentation. Thinking that maybe the chocolate or coffee did something to prevent the yeast from fermenting, I gave up on the beer but decided to hold off on dumping it. Six weeks after brewing the gravity reading was 1.030. How and when did this ferment? Did an infection consume the sugar?
Bob Hines
Chapman, Kansas
A
True mysteries are rarely encountered in a brewery when the facts related to a particular problem are at hand. The problem lies in obtaining the facts and this is particularly true when homebrewing. In a commercial brewing operation it is common for brewers to be in the brewery most of the time and in some of the larger breweries instrumentation and data collection is used to gather and track data related to production. Production staff and historical data are pretty handy when it comes to tracking down the ghosts that seem to haunt the brewery, but in cases like yours there is not much information to evaluate.
The beer you brewed had a fairly high original gravity and also contained a high proportion of specialty malts. Based on this information I would not predict a very low finishing gravity. Couple that with the single step infusion mash at 155 °F (68 °F) for one hour specified in the recipe and I suggest that 70% is a reasonable guess for the apparent degree of fermentation (how much extract is consumed during fermentation as measured using a hydrometer). Thirty percent of 1.090 is 1.027 and your final gravity was 1.030. This tells me that your OG and FG numbers are believable. When I solve problems I first begin by questioning the validity of the information at hand — because that is what Wizards do!
The other fact at hand is that you added an ingredient that contains fat to your wort; baking chocolate contains cocoa butter. You also added ground coffee beans and coffee beans contain oils. Fats and oils are the same general class of components that are deposited on the rim of a beer glass if you happen to be noshing on greasy finger foods while enjoying a frothy pint . . . well, perhaps previously frothy pint. Fats and oils are well-known anti-foaming compounds because they have a higher affinity for the surface of liquids than do foam-positive compounds from beer. This means that proteins and hop compounds normally involved in beer foam are prevented from stabilizing foam bubbles when these strongly hydrophobic molecules are present. In simple terms you may have had carbon dioxide escaping from your fermenting batch of Breakfast Stout with little to no commotion at the surface of the carboy. Some brewers intentionally add anti-foams to fermenters to suppress foam during fermentation and increase the capacity of their fermentation vessels.
I can understand everything so far, but now I am faced with the piece of evidence that I cannot believe and that is the seeming lack of carbon dioxide gas. When beer ferments, nearly half of the sugar (by weight) is converted to carbon dioxide gas and nearly all of this gas leaves the fermenter. Your beer did ferment, therefore carbon dioxide gas left the fermenter. Until physicists at CERN in Geneva present data showing that C6H12O6 does not release CO2 when fermented by yeast I will continue believing in fermentation as we know it. I think what happened is that you had a faulty carbon dioxide gas detector . . . I mean a leak in your airlock. Hmmm, I wonder if that is how they clocked those neutrinos moving a few nano-seconds faster than photons of light in their accelerator?
A leaky airlock would explain why your airlock wasn’t gurgling during fermentation and a slow fermentation would explain why shaking your carboy did not seem to generate much activity. Six weeks is a long time to ferment 60 gravity points and I think what happened is that you had a long and slow fermentation that never appeared to be doing much of anything. The only negative consequence of fermentations that drag out is the potential for contamination associated with slow pH reduction in the early hours of fermentation and off-flavors associated with under-pitching, often the cause of slow fermentation. Also, I don’t think contamination explains your observations. All microbes that consume carbohydrates for energy give off gas.
Q
I have been reading about a method of chilling called “no chill,” where the brewer simply pours the wort after flame out into a suitable water container, purges the air and seals it airtight. What are your thoughts?
Nick Rolheiser
Edmonton, Alberta
A
My first thought is that this method is certainly not new. Rapid chilling is a very recent development in the history of brewing. Prior to the advent of the plate heat exchanger, brewers had to wait for wort to cool prior to pitching. Most breweries eventually settled on coolships, which are large shallow pans resembling Olympic-sized kiddy pools, to cool wort prior to fermentation. Although cooling required only eight hours or so, wort contamination was a real issue with the coolship design. Then, in 1856, Jean Louis Baudelot invented a novel wort chiller and the brewing world was changed forever when his invention made rapid chilling a reality. The Baudelot chiller was copied and later modified into enclosed designs. Baudelot’s basic design is still widely used in all sorts of different heating and cooling applications.
There are two real problems with slow wort chilling. One is the risk of microbiological contamination. The other problem associated with slow wort cooling is DMS formation after wort boiling. The precursor for DMS, S-methyl-methionine, decomposes when heated and becomes DMS (DMS smells like cooked corn and most brewers consider it a defect in almost all beer types). Although much of this compound is transformed to DMS and removed with steam vapor during wort boiling, some does remain. This means that the wort DMS concentration increases after boiling and prior to cooling, and is especially noticeable if wort is in a sealed container that prevents the volatile DMS to escape.
The good news is that homebrewers do not have a very large volume of wort to chill and it is certainly possible to cool a carboy of wort in a reasonable time frame if the carboy is plunged into a cold water bath that is kept cold during cooling. Agitating the carboy will also dramatically increase the heat transfer rate during cooling. My personal preference is to cool wort using a wort chiller either in the kettle with an immersion chiller or en route to the fermenter with a plate or shell-in-tube chiller. I suppose if I were brewing on a desert island and only had the no-chill method I would make do, but neither one of us is stranded on an island.
