I was just curious, how long folks leave the beer in the fermenter. At day 5, my beer has been at steady gravity for 3, so I’m thinking keg and cold crash.
Depends on the wort and the yeast really. …but a standard 1.050-ish wort and my go-to Bry-97 I avg 5-6 days.
I’ll say it before Denny can. ;D
It’s up to the beer. Sounds like your is ready to go.
Smaller/average beers can often be done in 5 or 6 days. Bigger beers can take longer. sometimes much longer.
You have to let beer drive, it will tell you when you get there.
Paul
Good on ya!
I find that for most beers up to maybe 1.070ish, what usually works for me is 4-5 dys at 63, 2-3 days at 70-72, and 3 days at 35. Add a couple more at 35 if I’m dry hopping. But like Paul said, it depends
Every ferment is different. Not only do the grain bill and gravity influence fermentation times, but so do yeast strain, health and cell count, wort oxygen content, temperature, wort fermentability, and several other factors as well. Some of these may fall in line without your influence.
I won’t offer a hard and fast method to determine when to package, but will tell you what’s worked best for my beers. I always slightly over pitch, aerate and control fermentation temperature. Once Krausen begins to recede, I increase the temperature for a couple of days for a VDK rest and then take a gravity reading. If the gravity is where I expect it to be, I then reduce the fermentation chamber temperature to the low 40s to speed flocculation and clearing. If my recipe calls for dry hops, I toss them in at this time. After five days, the beer is kegged. Your personal experience should be the biggest guide. Your process is unique and will have a definite influence on what works best for you.
I wait for the beer to tell me it is done. That is when one sees the beer start to clear. If is the yeast is not floculating (clumping together) or sedimenting (falling out of suspension), it has not completed its job.
I leave it for however long it takes. Every batch is different. Yeast is alive and works at whatever pace it wants.
I think fermentation temperature is also a big factor. Yeast is much less active at 48F than 65F.
For me, regardless of style, I leave in the fermentor ( SS conical with temp control) anywhere from 2-3 weeks. Cold crash, finings, collect yeast then keg.
I set it and forget it, for 3 weeks.
And worth composition figures in, too.
Those of you who are leaving next in the fermenter for long periods in order for the yeast to “clean up” might be interested in this conversation I had with John Palmer…
100-150 years ago, fermentation was open, followed by maturation in a wooden cask. The beer
was prone to contamination. This could be mitigated by heavy hopping and long warm
maturation to wait for the bitterness to die down, or by long cold maturation (lagering) to use
temperature to keep the contamination down.
Yeast have 3 phases in their life cycle: Adaptation, High Growth, and Stationary. (See Yeast by
CW and Jamil) They do not have a maturation phase where they clean up byproducts. Adaptation
phase is where they take in oxygen and build sterols and other lipids, assess the sugar
composition and build enzymes, etc. Once those activities are done, they start the High Growth
Phase, eating and reproducing. The number of cell divisions is limited by their lipid reserves they
made during Adaptation. These reserves are shared with each daughter cell. When those lipid
reserves are exhausted, the cell stops reproducing. In addition, when those reserves are
exhausted, the cell is old and cannot eat or excrete waste efficiently across it’s cell membrane. A
yeast cell typically can reproduce about 4 times during a typical fermentation, after that it is old
and tired and tends to enter Stationary phase where it shuts down most of its metabolism and
flocculates, waiting for the next batch of aerated wort. Stationary phase is essentially an
inactivity phase, resting on the bottom.
Like I said, no conditioning phase as far as the yeast are concerned. Byproducts can be consumed
at any point during the high growth phase, but they are a lower energy source than sugar, so
guess what? Byproducts are not a biological priority. The brewer therefore needs to plan his
pitching rate and fermentation conditions such that the yeast run out of fermentable wort sugar
before their lipid reserves are exhausted and they go into stationary phase. Now you have a
majority of vigorous yeast that have only undergone 2 reproductions (for example), the sugar is
gone, and they are still hungry, so they turn to acetaldehyde and diacetyl as alternate energy
sources and maturate the beer. You can help this by doing a diacetyl rest by raising the
temperature a few degrees after the first half of fermentation, to keep the yeast active and eating.
Where in the fermentation? after the first half, 2/3 to 3/4, when most of the attenuation has
occured and raising the temperature is not going to cause rampant growth and the off-flavors
associated with it.
Today, we have closed stainless steel tanks which allow us to prevent oxidation, pull the yeast,
and control the temperature. This plus our understanding of the yeast cycle above changes the
way we ferment lagers, so now lager beer fermentation is started cooler to control yeast growth
and allowed or controlled to rise during fermentation to the diacetyl rest, such that ALL of the
fermentation and maturation is complete before the beer is cooled to lagering temperature. The
effect of temperature at this stage is strictly physical, increasing the strength of hydrogen bonds
to coagulate beer haze and help it settle out. The yeast are still susceptible to temperature shock
and lipid excretion, so the cooling to lager temperature 35-38F still has to be slow, i.e. 5F per
day.
Please note that this behavior and fermentation technique is applicable to ALL beers,
Wow, that is slow! I have heard people say limit the cooling to 1-2 F/hr before, but this is way slower than that. I usually take 2-3 days to cool from mid-60s to 34, but 5 F/day would require ~6 days for a “cold crash”. Really more of a gradual slowing than a crash.
FWIW, I ignore that and cold crash without any of the negative effects mentioned. As always, learn the science but do what works for you.
+1. I keg after ~65F fermentation is complete and stick the keg in a 34F fridge under CO2 pressure. It takes ~ a day or so I’d guess [emoji2369] I never tracked it.
I crash from 70-72 to 35 in 3-4 hours. If it caused problems I would stop doing it.
It’s not always 3 weeks, but I package when my schedule allows rather than following gravity readings for each batch. I have a good enough idea how long most of the yeasts I use need for a given gravity and temperature, and I give them a couple extra days to be on the safe side. A low gravity ale gets 7 days or so, while Belle Saison gets 3 weeks.
There is so much erroneous information in what John wrote that about the only thing that is correct is the level of contamination 150 years ago. I like and respect John, but he needs to stick with what he knows best and that is the brewing side of beer production, not the biological side of beer production.
He kind of got a few things correct, but he is absolutely wrong about what causes the shift from the log (exponential growth) phase to the stationary phase. What causes yeast cells to switch from the log phase to the stationary phase is achieving maximum cell density (i.e., the yeast cell population is self-regulating). That is why I urge people to pitch their starters at high krausen because all reproduction after a fermentation enters the stationary phase is for replacement only (i.e., high krausen signals the switch from the log phase to the stationary phase). When a mother cell buds a new daughter cell, she shares her ergosterol and unsaturated fatty acid (UFA) reserves with the daughter cell, which means that mother cells will exhaust more of their reserves if a starter is allowed to ferment beyond high krausen. Wasting ergosterol and UFAs results in a higher O2 requirement and a longer lag phase when the starter is pitched. Allowing a starter to ferment out places the cells in a quiescent state where they have undergone morphological changes that have to be undone when the culture is pitched, resulting an even longer lag phase.
What causes yeast cells to stop fermenting is the exhaustion of the carbon sources they can convert to energy. I cover carbon sources in my blog entry entitled “Carbon Credits” (see Carbon Credits | Experimental Brewing). Most brewing yeasts fall into the NewFlo genotype, which means that flocculation will not occur until mannose, glucose, maltose, sucrose and the more complex saccharides that a yeast strain can reduce to one of these sugars are exhausted. A very visible example of NewFlo flocculation occurs with Lallemand Windsor. The reason why that yeast flocs so early is because it cannot break maltotriose down into three glucose molecules via the two-step process of breaking maltotriose into one molecule of maltose and one molecule of glucose followed by splitting the maltose molecule into two glucose molecules. In essence, Windsor does not stop fermenting because it has exhausted its ergosterol and UFA reserves. It stops fermenting because it has exhausted the carbon sources that it can metabolize, which triggers flocculation.
John is also absolutely incorrect about the yeast not cleaning up things during the stationary phase. The main thing he got right is that slowing down exponential growth leads to cleaner beer because that is were most of the metabolic trash production occurs. I covered this information in detail in my blog post entitled “Have You Seen Ester?” (see Have You Seen Ester? | Experimental Brewing). The main reason why we do not want to introduce O2 into fermented wort is because it can cause diauxic shift, which results in yeast cells using ethanol as their carbon source. Ethanol is the result of a yeast cell’s anaerobic (fermentative) metabolic pathway being inefficient. If one introduces enough O2 after fermentation is complete, the cells will switch to using ethanol as a carbon source via their aerobic (respiratory) metabolic pathway, which is 100% efficient. The aerobic metabolic pathway converts carbon to energy, water, and carbon dioxide gas. The big dry yeast companies take advantage of the respiratory metabolic pathway’s higher efficiency by propogating in devices known as bioreactors. All brewing yeast strains are Crabtree positive, which means that they will follow the lag, log, stationary, quiescence pattern when the gravity of medium (wort) is above the Crabtree threshold. What happens in a bioreactor is that medium (molasses) is kept below the Crabtree threshold and continuously refreshed at rate where it never exceeds it. O2 is added and the medium is stirred to make it uniform. By propagating yeast cells in a bioreactor, Lallemand and Fermentis are able to produce more yeast using less carbon. We need to remember that sugar is a carbohydrate and carbohydrates are built as multiplies of a carbon atom bound to a water molecule. Glucose is C6H12O6, which is six times CH20.
One last thing, he also kind of got the number of times a mother cell buds in a fermentation correct. As I covered in my blog entry entitled “Yeast Cultures Are Like Nuclear Weapons” (see Yeast Cultures are Like Nuclear Weapons | Experimental Brewing), the yeast biomass grows at a rate of 2^n, where the symbol “^” denotes raised to the power of. The variable “n” is the number of replication periods that have elapsed. The number of replication periods required for a yeast culture to achieve maximum cell density after being pitch is calculated as the log base 2 of the number cells needed to reach maximum cell density divided by the number of cells pitched. Five gallons is basically 19 liters. If we pitch a 1L starter at high krausen then we need 19 times the number of cells pitched to reach maximum cell density. However, the yeast cells will not require 19 replication periods to reach maximum cell density because growth is exponential, not multiplicative; therefore, we need to take the log base 2 of 19. Most calculators due not have a log2 function, but can compute the log base 2 of 19 by dividing log(10) by log(2) using the base 10 log function.
number_of_replication_periods_needed = log(19) / log(2) = 4.24792751344359 replication periods
We can verify this result by raising 2 to the 4.24792751344359 power.
times_larger = 2^4.24792751344359 = 19
What determines how long it takes to reach maximum cell density time-wise is the length of the lag period plus the number of replication periods needed times the length of the replication period. At normal ale fermentation temperatures, the replication period is approxminately 90 minutes long. As we lower the temperature, the length of the replication period grows, which is why it takes longer to see visible signs of fermentation.
May I ask how you calculate your IBU’s ?
Thanks
That is one thing that I do not bother calculating anymore. I bitter using AAUs and taste. For one, I do not have an exact acid alpha (AA) content of the hops I am using. I merely have the AA content when the hops were analyzed and a crop year. Secondly, I have seen enough people send beers away for IBU analysis that did not come back anywhere near what was calculated that I have given up on the Tinseth and Rager methods. Both methods are approximations, but I guess that they are better than nothing when starting out with a newly designed recipe if one is attempting to brew to style. The reality is that without a quality lab, AAUs are as accurate a method of specifying bitterness as calculated IBUs at the home level. The only hops that truly count toward base bitterness are the kettle hops. Sure, late hop additions add bitterness, but they are in the boil for such a short amount of time that isomerization is incomplete. Alpha acid is insoluble in water. It has to be converted to iso-alpha acid, which is an isomerized (chemically changed) form of alpha acid before it will dissolved in water. That is why the hops added at the start of the are known as bittering hops and the hops that are added near the end of the boil are known as finishing hops.
My beef with the whole brewing software thing is that it attempting to insert precision where none is possible. I hold undergraduate and graduate degrees in the engineering side of computer science; therefore, to me, it is apparent that what brewing software calculates is little more than an illusion. Any bitterness or yeast cell calculations should be taken with a grain of salt. In my article entitled “Yeast Cultures Are Like Nuclear Weapons,” I cover the yeast calculator fallacy. That only way one is going to know for certain how many cells one is pitching is to take a sample from the starter and count viable cells on a hemocytometer. Very few amateur brewers are going to go through this trouble, so throw the darn yeast calculator away and work with knowns. One, if a starter makes it to high krausen without exhausting the medium first, it has hit maximum cell density. The average maximum cell density for brewing yeasts is 200 billion cells per liter. The difference between 200 billion cells and 400 billion cells is 90 minutes of propagation time at ale fermentation temperatures. The propagation time for the average White Labs culture in a 1L starter is two replication periods (180 minutes at room temperature), which means that the time between inoculating the starter medium and it being ready to pitch is usually under 12 hours, often significantly under 12 hours.
My advice to any new brewer is to skip using brewing software at least until one knows how to perform all of the brewing calculation using pencil paper. For example, calculating strike water temp is a very simple exercise in thermodynamics based on something know as specific heat. Twenty pounds of grain has as much specific heat as one gallon of water (i.e., one pound of grain is equal to 0.05 gallons of water specific heat-wise). For example, we are mashing 10 pounds at 1.25 quarts per pound of grist, giving us 10 * 1.25 = 12.5 quarts (3.125 gallons) of strike liquor. Ten pounds of grain is equal to 0.5 gallons of water specific heat-wise. If our grain is at 70F when we mash-in, how hot does the strike liquor have to be at mash-in to come to rest at 150F? Well, we need to have the equivalent of 3.625 (3.125 strike liquor + 0.5 specific heat of the grist with respect to 1 gallon of water) gallons of water specific heat-wise come to rest at 150F.
Multiplying 3.625 by 150, yields 543.75
Subtracting 0.5 (the heat content provided by the grist in with respect to water) * 70 = 35 degrees from 543.75 yields 508.75.
Dividing 508.75 by 3.125 = 163 degrees F
We need 3.125 gallons of water at 163F to hit our strike temperature; however, unless the mash tun has been preheated, it will sink heat from the mash until its temperature stabilizes with that of the tun. That is why we usually mash-in with 165F degree strike water at 1.25 quarts per pound when using a cooler mash tum to achieve a rest temperature of 150F. It is that simple.
In the end, I am firm believer that starting out with brewing software keeps smart people stupid. The only calculation in brewing that requires a computer is mineral additions. Mineral additions can be calculated by hand, but it is not fun. That is one thing on which Denny and I firmly believe. Denny s old-school like me. We had to learn all of the calculations in brewing before we could brew all-grain beer. That is also why we can formulate a recipe and a process without brewing software. Working this way, a brewer develops rules of thumb over time.