Author Topic: How long do you ferement  (Read 2939 times)

Offline denny

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Re: How long do you ferement
« Reply #15 on: August 29, 2020, 10:25:34 am »
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 ~65*F fermentation is complete and stick the keg in a 34*F fridge under CO2 pressure. It takes ~ a day or so I’d guess I never tracked it.


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I crash from 70-72 to 35 in 3-4 hours. If it caused problems I would stop doing it.
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Offline erockrph

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Re: How long do you ferement
« Reply #16 on: August 29, 2020, 10:27:13 am »
I set it and forget it, for 3 weeks.
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.

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Offline Saccharomyces

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Re: How long do you ferement
« Reply #17 on: August 29, 2020, 01:01:38 pm »
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.....

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 https://www.experimentalbrew.com/blogs/saccharomyces/carbon-credits).  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 https://www.experimentalbrew.com/blogs/saccharomyces/have-you-seen-ester).   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 https://www.experimentalbrew.com/blogs/saccharomyces/yeast-cultures-are-nuclear-weapons), 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.
« Last Edit: August 29, 2020, 01:12:42 pm by Saccharomyces »

Offline Fire Rooster

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Re: How long do you ferement
« Reply #18 on: August 29, 2020, 02:52:56 pm »
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.....

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 https://www.experimentalbrew.com/blogs/saccharomyces/carbon-credits).  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 https://www.experimentalbrew.com/blogs/saccharomyces/have-you-seen-ester).   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 https://www.experimentalbrew.com/blogs/saccharomyces/yeast-cultures-are-nuclear-weapons), 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

Offline Saccharomyces

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Re: How long do you ferement
« Reply #19 on: August 29, 2020, 03:54:46 pm »
May I ask how you calculate your IBU's ?

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.
« Last Edit: August 31, 2020, 02:52:21 am by Saccharomyces »

Offline Richard

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Re: How long do you ferement
« Reply #20 on: August 29, 2020, 05:56:21 pm »
You may have a point with calculation software, but there are some packages that offer more than just calculation. BeerSmith has an impressive database of ingredients and also provides a nice way to print out brewsheets and store brewing logs. I have my own spreadsheet that uses my own equations for strike water, volumes and gravities at various times during the brew day, and I use those to compensate for some small errors in BeerSmith (e.g. liquid absorbed by hop pellets in a heavily hopped NEIPA). I still like and use BeerSmith, though, for all the other non-calculation reasons I cited above.

I also disagree with your "only-scientists" attitude. I can calculate strike water temperature from conservation of energy, but that doesn't make me a better brewer. I know people who cannot do that calculation but who can brew great beer. One of the great things about modern technology is that people who understand the technical issues can do the mechanics and make their results available to people who don't need to know the underlying basics. I know lots of people who happily and effectively drive cars without understanding thermodynamics or any of the underlying science or engineering. I know people who manage web sites and blogs but could not code in raw HTML and don't know packet structure. Should we only allow people to post on this forum if they demonstrate that they know all of the underlying technical details of Ethernet and TCP/IP communication? NO! That doesn't make them better brewers or better people. They can still have useful offerings even if they don't understand all of the science and technology  behind what they do.
« Last Edit: August 29, 2020, 09:36:53 pm by Richard »
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Offline Fire Rooster

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Re: How long do you ferement
« Reply #21 on: August 30, 2020, 02:59:17 am »
Over a year ago the internet was scoured for hop utilization percentages.
Found a couple and averaged them, forget the sources.
Modified formula to compensate for concentrated wort, which lowers hop utilization.
Forget how that was done, a while ago, gives an IBU ballpark guess, so the hop schedule
can be modified based on taste preferences.

(Hop OZ * Hop AA) * (Hop Utilization % for 1 US Quart / 7.25) * 100 * Quarts = IBU

Hop Utilization % for 1 US Quart
60min = 1.55
55 min = 1.5
50 in = 1.405
45 min = 1.345
40 min = 1.14
35 min = 0.94
30 min = .765
25 min = .605
20 min = .505
15 min .40
10 min =.30
05 min = .25

Example:  1 Ounce Simcoe (AA 11.3) @ 45 min, 4.25 gal (17 quarts)

(1 * 11.3) * (1.345 / 7.25) *100 * 17 = 35.6 IBU







« Last Edit: September 03, 2020, 02:03:46 am by Fire Rooster »

Offline BrewBama

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Re: How long do you ferement
« Reply #22 on: August 30, 2020, 08:03:57 am »
Predicting IBUs is a bit of a "black art", because there are so many variables and there is so much variability. The only way to really know the IBU level of a beer is to have it professionally tested. The results of the evaluation is usually very different than predictive models.

I realize the BU:GU ratio has issues and may not tell the whole story, and likewise the Tinseth IBU calculation is suspect, but it’s what we have so I use them as a benchmark to evaluate beer. After that my perception is used for adjustments.

I don’t recall where I got this but I use it as a reference to plan by:

            * American Amber: 0.619
            * Bohemian Pilsner: 0.800
            * Oktoberfest/Marzen: 0.449
            * Traditional Bock: 0.346
            * Blonde Ale: 0.467
            * California Common: 0.735
            * Ordinary Bitters: 0.833
            * American Pale Ale: 0.714
            * Brown Porter: 0.576
            * Dry Irish Stout: 0.872
            * English IPA: 0.800
            * Weizen/Weissbier: 0.240
            * Belgian Trippel: 0.375


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Offline Saccharomyces

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Re: How long do you ferement
« Reply #23 on: August 30, 2020, 08:15:01 am »
I also disagree with your "only-scientists" attitude.

You are entitled to disagree with me. However, the one constant I have observed is that the people who stick with the hobby for more than a year or two embrace the whole of brewing. They are usually very inquisitive people who tend to be life long learners. These people are not satisfied with know how to do something. They want to know why something works.

Anyone who cannot brew without software or a detailed recipe is not a brewer. That does not make him/her a bad person, just limited. What I have presented here is trivial compared to what one has to learn in the U.C. Davis brewing program. The book entitled “Brewing”  by Michael Lewis is used at that course. Anyone lacking basic brewing math does not stand a prayer of making it through that book. If you look at the prerequisites for that course, you will find math, physics, and chemistry on the list.

In the end, we all brew using rules of thumb. Mash-in strike water temperature for a specific rest temperature at a given hydration rate is a prime example of a rule of thumb. However, understanding concepts like specific heat afford a brewer the ability to calculate boiling water volumes necessary to hit target rest temperatures in a step infusion mash as well as calculate the temperature at which the main mash needs to be when combing it with near boiling gelatinized cereal to hit a desired rest temperature in the combined mash. The reality is that a group does not build a vocation or avocation up by dumbing it down. Dumbing a vocation or avocation down may increase the size of the group, but the quality of the group suffers.  It is up to the people who know more advanced material to share the “whys” and to challenge themselves and others to improve their knowledge of their pursuit.  I am challenging the people in this hobby who rely on software to be able formulate recipes, achieve desired gravities at specific volumes, and hit rest temperatures to learn the fundamentals of brewhouse math and physics. We can leave the biochemistry and microbiology of fermentation for another day. Software should be a tool, not a crutch.
« Last Edit: August 31, 2020, 02:58:02 am by Saccharomyces »

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Re: How long do you ferement
« Reply #24 on: August 30, 2020, 08:24:01 am »
May I ask how you calculate your IBU's ?
Thanks

Rooster, you may be interested in my quick & dirty method for IBU calculation. It comes extremely close to Tinseth method and can be figured out on a scrap paper or napkin or maybe even in your head.  Here’s what I do:



Cheers.
Dave

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Re: How long do you ferement
« Reply #25 on: August 30, 2020, 08:30:30 am »
May I ask how you calculate your IBU's ?
Thanks

Rooster, you may be interested in my quick & dirty method for IBU calculation. It comes extremely close to Tinseth method and can be figured out on a scrap paper or napkin or maybe even in your head.  Here’s what I do:



Cheers.

Keep in mind that HlenTinseth has said his formula won't necessarily be accurate for anyone but him.
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Offline denny

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Re: How long do you ferement
« Reply #26 on: August 30, 2020, 08:32:46 am »
Mark, if I may.....you seem to have fallen into one of the traps I did.  You are implying that everyone should brew for the same reasons you do.  Your thought process is great for you, but so far from why I brew.  Pleaseunderstnd that not all homebrewers have the same goals and that different methods work for different people.  It took me a long time to learn that.
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Offline BrewBama

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How long do you ferement
« Reply #27 on: August 30, 2020, 08:39:15 am »
May I ask how you calculate your IBU's ?
Thanks

Rooster, you may be interested in my quick & dirty method for IBU calculation. It comes extremely close to Tinseth method and can be figured out on a scrap paper or napkin or maybe even in your head.  Here’s what I do:



Cheers.
That’s a handy little nugget of information right there.

Mark, if I may.....you seem to have fallen into one of the traps I did.  You are implying that everyone should brew for the same reasons you do.  Your thought process is great for you, but so far from why I brew.  Pleaseunderstnd that not all homebrewers have the same goals and that different methods work for different people.  It took me a long time to learn that.

Someone who buys a kit and follows the directions to a T without doing any math is just as much a brewer as any other. Though you are highly respected, you don’t get to decide who’s a brewer and who isn’t Mark. Sorry. There’s room for everyone.

I prefer to use software because it’s fast and easy. Can I do the math? — yep. Do I want to? — nope.

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« Last Edit: August 30, 2020, 09:19:44 am by BrewBama »

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Re: How long do you ferement
« Reply #28 on: August 30, 2020, 11:44:39 am »
Keep in mind that HlenTinseth has said his formula won't necessarily be accurate for anyone but him.

"Good enough" is better than nothing, IMO.
Dave

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Offline goose

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Re: How long do you ferement
« Reply #29 on: August 30, 2020, 12:09:05 pm »
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.
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.

I do the same thing as Denny.  I have never seen any negative effects either, but the science is good to learn and know.
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