My SRM is constantly darker than the recipe predicts. I am a Brew-In-A-Bag (BIAB) brewer, I use reverse osmosis (RO) water and add salts according to the water analysis on Brewer’s Friend and I never hit the color. My last recipe was an American wheat with 5 pounds (2.3 kg) of 6-row malt, 4.5 pounds (2 kg) of white wheat malt, 0.5 pound (0.23 kg) of Carapils and 1 pound (0.23 kg) of honey malt. The predicted color was 6.5 SRM and right now in the secondary it is a good 15 or 16 SRM. Before this, I did a lawnmower ale, and it had nothing but 2-row malt, flaked corn, and Carapils in it. The SRM was supposed to be 3 and it is a good 10 or 11.
The origins of beer color usually fall into two primary categories; malt-related and process-related. The method used to approximate beer color uses a weighted average of the various contributors of ingredient extractions in beer, their respective laboratory colors, wort original gravity, and a process factor. Say you have a recipe that derives 90% of the extract from 2-row malt with 2 °Lovibond and 10% of the extract from 10 °Lovibond Munich, and the wort original gravity (OG) is 12 °Plato. The predicted beer color math would look like this:
Beer Color (approximate) = (0.90 x 2 + 0.10 x 10) x (12⁄8) x “beer color factor”
The “12⁄8” part of the above equation relates wort gravity of the beer being brewed to the wort gravity used in the lab test for malt color, and the “beer color factor” (BCF) is an empirically derived value that relates malt/wort color to beer color, and is typically about 80%. What you are seeing with your brews is a BCF that differs from that used by the author(s) of your recipes. By the way, I am not sure everyone uses a BCF when approximating beer color, so if you go Googling “beer color factor” or “BCF” you probably will come up with little to no information because I am pretty sure this is a term I made up 25 years ago and have never uttered publicly until now!
All process-related sources of color are associated with this BCF. Some of the process things that relate to beer color are tannin extraction, wort pH, wort oxidation, boiling duration, boiling intensity, and beer filtration. Minimizing tannin extraction, keeping mash pH in the 5.2–5.4 range, adjusting pre-boil wort pH to 5.2 or lower, adding calcium sulfate or calcium chloride to wort before boil, minimizing wort oxygen pick-up during wort collection and before boiling, and avoiding excessive wort evaporation during wort boiling are some of the things that can be done to minimize beer color from a fixed malt bill. Few homebrewers filter their beer, and beer filtration is not something typically used by commercial brewers to specifically affect color (special carbon filtration is used to make clear beers, but those are not exactly common); however, brewers who filter need to consider that filtration tends to lighten beer color, and that not all filtration methods behave the same with respect to color loss.
It is very easy to get mentally distracted when thinking about process and color, and one of the common rabbit holes that some brewers find themselves exploring is limiting wort boil to the extreme. The thing to keep in mind when considering this is that pale lagers undergo pretty aggressive wort boils, so the key to brewing light beer does not require a super-short boil. In your case, however, your darker-than-expected beer is most likely related to wort boiling. The three most effective methods to look toward are: 1) Limiting wort evaporation during boiling to about 10%, 2) Adjusting pre-boil pH to 5.0–5.2 with lactic or phosphoric acid (you can also add calcium to accomplish the same thing, but adding acid is easier because calcium reacts with wort components during the boil and things get more complex), and 3) Minimizing splashing during collection.
Dr. Michael Lewis told a story in a lecture at UC-Davis about wort boiling that has stuck with me since hearing it in 1991, and I will paraphrase my memory. The story goes that a large US brewery was having a large Japanese brewery brew their pale-colored lager, and the beer was darker than the specification. So a brewmaster from the US brewery called his contact in Japan to discuss. Apparently the conversation went something like, “Ohayo gozaimasu, it seems that you are not filling your kettle with the special fill pipe that we have specified,” followed by a long pause on the phone and finally the question, “So, why do you think we have removed the special fill pipe?”
In this particular case, the brewery had an older brew kettle that filled from the top and the US brewery asked for a special fill pipe to be installed to minimize air pick-up and wort splashing before the boil. Since the pipe was not easy to clean, the Japanese brewery removed the pipe only to be busted by brewing a darker-colored version of this particular beer. I have probably mangled the memory of this story, but that is my recollection and I am sticking to it! The moral of the story is that small, seemingly inconsequential details, in a brewery of any size, are often quite influential to the brewing process.
I notice that many of the authors in BYO advocate for Polyclar as a clarifier. The IPA Style Guide calls for that in most of the recipes therein. After reading about it, my fear is that Polyclar would remove the yeast that I would need to bottle condition. Would you recommend using Polyclar if I bottle condition? Would you only recommend Polyclar if someone force carbonates?
Polyclar is a trade name for the fining agent commonly known as PVPP, or polyvinylpolypyrrolidone . . . say that four times real fast to test your tongue-twister skills. The chemical structure of PVPP resembles a protein, and PVPP finings bind tannins/polyphenols. So the very short answer to your question is that PVPP can be used for bottle-conditioned beers because it is not a yeast fining, and therefore does not reduce the yeast density after use.
Your question is a great launching pad for me to dive into a bit more detail about this particular fining, however. PVPP is used to remove tannins/polyphenols (I will simply refer to these compounds as tannins) from wort and beer, and the primary purpose of this is to improve the brew’s colloidal stability, or propensity to stay clear in the package. You can add PVPP to hot wort to remove tannins before fermentation, and you can add PVPP to remove tannins after fermentation. Some breweries use it in the brewhouse and in the cellar, not so much as a belt-and-suspenders approach, but more to remove tannins at stages in the brewing process when they can be removed.
Before the IPA craze of the last decade, most tannins in the brewing process came from malt and a lesser amount came from hops. During this period of brewing history, PVPP was mainly added to beer before filtration in an effort to reduce the concentration of haze-active tannins in the final package. As hopping rates have increased and beers have generally become bigger in all aspects, the use of finings throughout the process has also increased. Many brewers are adding PVPP in the brewhouse and in the cellar to remove tannins, and may also be adding carrageenan (aka Irish moss) in the brewhouse to remove proteins, yeast finings such as isinglass (collagen from the swim bladders of certain fish) or silicic acid (tradename Biofine Clear) after fermentation to remove yeast, and possibly an enzyme that targets proline-rich, haze-active proteins (tradename Clarity Ferm or Brewer’s Clarex) before fermentation.
The only finings that pull yeast out of beer are isinglass, gelatin (collagen from animal sources other than fish bladders), and silicic acid. If you use yeast finings and want to bottle condition your beer, you should try adding a small, fresh dose of yeast to your beer prior to bottling. Otherwise, you have no worries. But do consider the use of finings to improve beer clarity and to remove some of the harsh notes that can accompany excess protein and tannin in your brew.
Does the temperature of your beer matter when you add priming sugar before bottling? Can you prime when your beer is cold?
Costa Mesa, California
Beer temperature is very important for priming, but the beer temperature is not critical when the priming sugar and yeast, if fresh yeast is used, are added to beer. Most commercially produced, bottle-conditioned beers are stored around 68 ˚F (20 ˚C) until conditioning is complete, and are then moved into a cooler environment for extended storage.
A common method used these days by these commercial bottle-conditioned brews begins with cold beer that has been clarified with a centrifuge, a filter, or a combination of the two. Following clarification, a small dose of fresh yeast and priming sugar is added to beer and briefly stored in an agitated bright beer tank. At this point, there is typically about 2.2 volumes of carbon dioxide in the cold beer, usually a product of natural carbonation at ale fermentation temperature at a pressure of about 15 psi, and about 250,000 to 1,000,000 yeast cells per milliliter of beer. Agitation is achieved either with a mixer or a pumped recirculation so that yeast does not settle while the beer is in the bright beer tank.
The beer is now ready for bottling and is counter-pressure filled into bottles. Modern beer fillers use a system called double pre-evacuation to remove oxygen from empty bottles before filling. These systems work by pressurizing the bottle with carbon dioxide, followed by a vacuum step that evacuates the gas from the bottle, followed by a second pressurization step with carbon dioxide. The beer then flows into the bottle, typically through short fill tubes that direct the beer down the surface of the bottle. Once filling is complete, the headspace pressure is reduced to atmospheric pressure.
If everything has gone well, there is no foam in the bottle. As the bottle is transferred to the crowner, a fine jet of water hits the top of the beer. This so-called “fobbing” operation pushes oxygen out of the bottleneck and allows the beer to be “capped on foam.” The oxygen content of a bottle of beer filled using this technology is typically less than 50 parts per billion (ppb), and often as low as 20 ppb.
In a normal bottle operation without a pasteurizer, filled bottles are usually labeled and then packed into cases. Breweries that are really set up for bottle conditioning delay labeling until the bottles are warmed by using a bottle warmer, which is a slight adaption of tunnel pasteurizers. Bottle warmers, and tunnel pasteurizers, use a warm shower to heat the beer in the bottle. This actually makes labeling easier since warm bottles do not sweat like cold bottles. But the reason for warming bottles of beer destined for the conditioning cellar is to speed the conditioning process, as large stacks of cases of cold beer take a surprisingly long time to equilibrate with the
ambient temperature. The inventory value of packaged beer is the most expensive beer in the brewery, and waiting for bottles to condition is a costly endeavor.
This was a pretty long plunge in the deep end of commercial brewing, and is something I try to avoid without good reason. There are a few useful tips to glean from these operations.
The fact that most commercial breweries bottle these beers with sufficient carbon dioxide content to fob and cap on foam is interesting because it says something about the susceptibility of bottle-conditioned beers to oxidation . . . bottle-conditioned beers are not immune to oxidation and commercial brewers who bottle condition are usually as concerned about oxygen pick-up during packaging as brewers who bottle fully conditioned beer. It is also interesting to note that bottle-conditioned beers are often very clear before fresh yeast and priming sugar are added. Finally, the short period used to condition most of these beers is a stark contrast to the time periods used by most homebrewers for the same process.
When should a diacetyl rest be done? I keep hearing different ways of doing it, depending who i ask. some say to wait until fermentation is over to do a diacetyl rest, but others I ask say that it should be done before fermentation is complete. When is the best time?
High Point, North Carolina
I like to do a diacetyl rest at any point in the process that makes for a diacetyl-free beer, and as you have correctly heard, there is no one way to do this. I will, for the moment, assume that you are using a yeast strain that is known to result in buttery beer if special steps are not taken to mitigate the issue. And I will later in this answer cover some things that can be done with less problematic yeast strains.
Butter bombs are often the product of very flocculent ale strains that settle to the bottom of the fermenter before their brewery work is completely finished. What happens in this scenario is that alpha acetolactate, the diacetyl precursor secreted by yeast during fermentation, is oxidized into diacetyl after the yeast cells have packed up their bags and headed south to the bottom of the fermenter. Oxidation of alpha acetolactate is how diacetyl ends up in clean beers (Pedicoccus contamination is another, much more troublesome story), and managing this reaction is the key to diacetyl control.
If you create an environment that allows diacetyl to bloom in the presence of healthy, active yeast, then you have a good chance that these yeast cells will absorb diacetyl and reduce this aromatic compound into butanediol, which is essentially aroma-neutral. The easiest thing to do, with any brew, is to hold the beer at about 68 ˚F (20 ˚C) for at least 2 days in the presence of happy yeast, after the beer gravity has stabilized around the target finish gravity. But the real issue is that very flocculent yeast strains do not always finish fermentation before dropping out of the beer. This is why measuring gravity is important, and why rousing is a fairly common technique used with flocculent yeast strains. If you are using one of these strains, you want to verify your end gravity has been achieved, rouse when in doubt, and hold your beer for at least 2 days at 68 ˚F (20 ˚C) before cooling and moving on with your brew. This is the ale way of warding off diacetyl.
Lager brewers tend to do things a bit differently because things happen at a slower pace at the cool temperatures used for lager beer fermentation. One technique is to allow the fermentation temperature to increase at the tail-end of the drop in beer gravity (most flavor-active compounds from fermentation form early in the process, so the rise in temperature does not make for fruity lagers). The higher temperature speeds the conversion of alpha acetolactate to diacetyl, and diacetyl is then quickly reduced to butanediol in the presence of active and healthy yeast cells. Some brewers have a more active hand with this method and move their lager fermentations from a cool environment (50–54 ˚F/10–12 ˚C) to a warm environment (68 ˚F/20 ˚C). In both cases, the goal is to convert the diacetyl precursor to diacetyl in the presence of active yeast. Most lager yeast strains are much less flocculent than ale strains and are active down to about 38 ˚F (4 ˚C), so cold, long lagering works quite well for brewing low-diacetyl beer, it just takes longer.
Another handy technique used by lager brewers to reduce diacetyl in finished beer is kräusening. This is when actively fermenting beer, usually about 24 hours into active fermentation, is added to beer that has completed primary fermentation. Kräusening not only helps to reduce diacetyl in the finished beer, it also helps ensure that primary fermentation is complete, and is a great brewing method to know how to use as a curative for stuck fermentations. Although kräusening is generally associated with lager brewing, there is no rule preventing ale brewers from also kräusening.