Calculating gravity and estimating required yeast cells for yeast starter

[saeven]

Hey guys. Tomorrow is the big day (I think). I pitched a yeast starter last night at midnight (1L propper/water and 1 bag of wyeast 1388 belgian strong). I am making a ~7.5% golden ale.

How do I know if/when the cells are ready to be pitched into the wort? I found a nifty calculator online for it:
https://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/But. to be honest, don't really know what i'm doing. How do I know what the OG is and how do I know the gravity for the starter?

Thank youuuuuuuuuuuu I need help

 

[VikeMan]

Propper, when mixed with water per the instructions, makes a starter wort with a gravity of 1.040.

For the beer wort, does your recipe not have a target original gravity (OG)?

IMO, a 1 Liter starter with a Wyeast smack pack is going to be a bit small for a beer that big (assuming a 5 gallon batch).

ETA: But it will be better than just using the smack pack without any starter.

 

[saeven]

The recipe gives these values:
OG (est): 1.067
FG (est): 1.011

What would be an easy fix then? Just lower the total volume?

 

[VikeMan]

What would be an easy fix then? Just lower the total volume?

If I understand your question, yes you could scale the recipe down to a smaller batch size better suited to the yeast you'll have from the starter. But it's not absolutely necessary.

And good on you for exploring yeast calculators. They can definitely be a big help.

 

[saeven]

What I don't understand is there doesn't seem to be a "time" portion to the above calculator. You would think if I gave it more time, I'd get more yeast cells.

Also, thinking about just multiplying everything by 0.67 in order to reduce all the ingredients to be more in line with my starter

8lb LME to 5.36lb LME
boiled in 6 gallons to boiled in 4 gallons
top up to 5.25 to top up to 3.5

Agree?

 

[VikeMan]

What I don't understand is there doesn't seem to be a "time" portion to the above calculator. You would think if I gave it more time, I'd get more yeast cells.

So, the time is "whenever it's done." You want to use up all the sugar in the starter wort, thus making the maximum amount of yeast cells (that the calculator assumes you'll make). Assuming you don't have a stir plate, and instead will be manually giving the starter an occasional swirl/shake, that could take a couple days. You'll know it's finished when you swirl it and it no longer produces significant foam (CO2 escaping).

Also, thinking about just multiplying everything by 0.67 in order to reduce all the ingredients to be more in line with my starter

8lb LME to 5.36lb LME
boiled in 6 gallons to boiled in 4 gallons
top up to 5.25 to top up to 3.5

Agree?

You'll be making more of a Belgian Pale/Blonde than a Golden Strong, but I could see this making a tasty beer. If you decide to do this, you might want to cut back on hops as well. (Maybe that's what you meant by "everything.")

 

[saeven]

I have had it on a stir plate since midnight. A lot of things I read say 12-24-36 hours. A pretty big range lol. If I target using it by tomorrow around this time, that will be at about 36 hours.. Just want to confirm that it won't "hurt" the yeast if they are in the starter for longer than they require?

 

[saeven]

Thinking about maybe even cold crashing it in the fridge at midnight tonight (that will be at 24 hours).. and then decanting off some wort and bringing to room temp before using tomorrow

 

[VikeMan]

I have had it on a stir plate since midnight. A lot of things I read say 12-24-36 hours. A pretty big range lol. If I target using it by tomorrow around this time, that will be at about 36 hours..

Ah, ok. You have stir plate. That's great. You can pull your flask off the plate and swirl (to test for significant CO2 breakout) just like you would with a non-stirred starter. Stir plate starters are, in my experience, almost always finished within 24 hours, often much faster.

Just want to confirm that it won't "hurt" the yeast if they are in the starter for longer than they require?

The only "harm" in letting it go longer is that once the cells have been made, they start to die (they do that in the smack pack also), and the die-off happens faster at higher temps. Once the starter is finished, it's best to refrigerate it, if it won't be used right away. And if the yeast floccs out, you can decant, which as I type this I see you're mentioning in a new post.

 

[saeven]

You're my knowledge. And I highly appreciate it. Sorry if i'm annoying you.

You said it will be more like a belgian pale/blonde instead of a golden strong. Why do you say that even if I reduce the working volume/ingredient additions and keep the current yeast starter volume/cells?

 

[VikeMan]

You said it will be more like a belgian pale/blonde instead of a golden strong. Why do you say that even if I reduce the working volume/ingredient additions and keep the current yeast starter volume/cells?

Sorry, my mind somehow jumped from scaled down volume to thinking about scaling down the gravity without changing the batch size. Clearly that's not what you were saying at all!

 

[saeven]

Haha no problem!

One final question for now I think: After I boil the LME, adding in the hops as stated, chill to 66F, top up if needed.

Since I have the fermzilla, could I at this point transfer to the fermzilla tank and then pitch my yeast? And plan on adding honey ~3 days later, and keep it in the fermzilla for ~3 weeks or until complete?

That's my only gray area as of now.. when I move it to the fermzilla.

 

[VikeMan]

One final question for now I think: After I boil the LME, adding in the hops as stated, chill to 66F, top up if needed.

Since I have the fermzilla, could I at this point transfer to the fermzilla tank and then pitch my yeast?

Yes, definitely transfer the wort to the fermenter as soon as it's chilled.

And plan on adding honey ~3 days later, and keep it in the fermzilla for ~3 weeks or until complete?

If adding honey to the fermenter, I'd recommend doing that at "high krausen," which more or less signals the most active point in the fermentation. That's likely to happen before day 3. Probably more like 48 hours after pitching, give or take. But you'll know when it's there, because there will be lots of foamy stuff (krausen) on the surface and the wort will be churning.

 

[saeven]

Hey guys.. aka my savior, Vikeman.

Brew day is done. I have a few issues.. although I dont know how minor/major they are:

1) I added the malt extract at 150F, not realizing it had to be 212F. So at that point, I increased temp up to 212F with malt extract and water.
2) When I took my yeast starter out of the fridge, i poured off the top (and might have poured off some of the yeast? unknown honestly. If i did it was only a little bit
3) My OG was about 1.04/1.05.. The recipe says it should have been 1.067. I was wondering.. could that even be due to the specific type of malt extract I used?
4) Chilling from 212F to 66F was initially easy then got hard. I got to 80F no problem. Getting from 80F to 66F-ish involved me putting the wort into the fridge for some time to have it cool. When the wort was done to when I pitched the yeast was probably ~3 hours.

I now have my wort/yeast combo in the fermzilla in my temp controlled fridge. Temp is currently 67F (woohoo!)

I'm wondering if since my OG was lower than expected, I should add some honey (maybe 0.5 lb) to the fermenter tomorrow, to attempt to give the yeast more to chew on, then add another ~1lb 2-3 days from now, to give the beer more flavor.

All in all, I'd say it went pretty well!

 

[VikeMan]

First, I don't see any major issues, so let's break down your concerns...

1) I added the malt extract at 150F, not realizing it had to be 212F. So at that point, I increased temp up to 212F with malt extract and water.

LME does not have to be added at 212F. As long as it isn't allowed to scorch on the bottom before mixing, it's fine.

2) When I took my yeast starter out of the fridge, i poured off the top (and might have poured off some of the yeast? unknown honestly. If i did it was only a little bit

If it was only a little bit, I wouldn't lose any sleep over it.

3) My OG was about 1.04/1.05.. The recipe says it should have been 1.067. I was wondering.. could that even be due to the specific type of malt extract I used?

I popped your recipe into BrewCipher and got a post-boil OG of 1.055. I don't know why your recipe said 1.067, but I can think of two possibilities...
A) The recipe was for Dry Malt Extract (not Liquid)
B) The OG included the impact of the later addition of Honey (if honey was part of the recipe)

Also, since BrewCipher computed 1.055 (for LME), and you seem to have got something between 1.040 and 1.050 (?), any of the following could account for that...
- You ended up with more than the intended volume of wort (topped off too much).
- The top-off water and the wort weren't mixed thoroughly before taking the hydrometer sample. <--- very common beginner issue
- Measurement error (bad hydrometer or mis-read)

4) Chilling from 212F to 66F was initially easy then got hard. I got to 80F no problem. Getting from 80F to 66F-ish involved me putting the wort into the fridge for some time to have it cool. When the wort was done to when I pitched the yeast was probably ~3 hours.

If your wort and kettle were sanitary, there's nothing to worry about here. A couple ways to improve chilling time:

- Assuming you were using an immersion chiller: When you chill with groundwater (or any water), the rate of chilling starts off very fast and slows down more and more as you get closer and closer to the temperature of the water. When my water is warm-ish, I chill until the rate of chilling slows significantly, and then I use a cheap pond pump to recirculate ice water through the chiller, which makes that last stretch go very quickly.

- Assuming you were using a stationary "ice water bath": consider getting an immersion chiller.

I'm wondering if since my OG was lower than expected, I should add some honey (maybe 0.5 lb) to the fermenter tomorrow, to attempt to give the yeast more to chew on, then add another ~1lb 2-3 days from now, to give the beer more flavor.

So, if the original recipe's predicted OG included honey that hasn't been added, just add that at high krausen. With your batch size, a pound of honey should raise the OG by about 10 points, from (say) 1.055 to about 1.065.

 

[saeven]

Great! That's what I will plan on doing then.. Unofrtunately when I woke up this morning the temp was done to 60F.. I'm in the process of raising it to 66-70F now but I assume that will delay high krausen/adding of the honey.

 

[saeven]

This is what my "krausen" is looking like right now.. It's definitely doing something. I accidentally broke off the airlock on top (#facepalm). Bought another one but won't get here until tomorrow.

Question is: How do I know when it's at "high krausen"

Also, what's the best way to take a sample for hydrometer testing? Sterile sample seems pretty impossible.

 

[VikeMan]

This is what my "krausen" is looking like right now.. It's definitely doing something. I accidentally broke off the airlock on top (#facepalm). Bought another one but won't get here until tomorrow.

I'd at least keep it covered with a piece of sanitized foil. It looks like maybe you already did that?

Question is: How do I know when it's at "high krausen"

The krausen is looking good. Do you see the wort churning below? If so, you're probably there. If it's not yet, I'd wait.

Also, what's the best way to take a sample for hydrometer testing? Sterile sample seems pretty impossible.

A sanitized wine thief or a sanitized turkey baster are a couple of ways.

 

[saeven]

Sanitized turkey baster is a great idea! Didn't think of that.

I don't see anything moving if that's what you mean by churning. There is a lot of foam but I don't see any other activity.

 

[saeven]

Well actually, if I shine a light onto it I can see stuff moving all over the place.. Wouldn't say it's going too crazy though

 

[VikeMan]

Well actually, if I shine a light onto it I can see stuff moving all over the place.. Wouldn't say it's going too crazy though

It will probably pick up steam sometime soon. At that point, I'd go ahead and add honey.

 

[saeven]

Cool. Will do. Last question for a bit: do I mix while adding the honey or just add the honey and let it fall to the bottom?

 

[VikeMan]

Cool. Will do. Last question for a bit: do I mix while adding the honey or just add the honey and let it fall to the bottom?

Just add it as gently as possible. It should get mixed around a bit by the active fermentation, and even if it doesn't, the sugars will dissolve and the yeast will find them.

 

[saeven]

It looks basically the same as yesterday. I've increased the temp to ~70-72F now to try to increase activity. If I shine a light I still see stuff moving all around, but not a ton of bubble production/churning going on. Still a ~1/2 inch layer of foam.

 

[VikeMan]

It looks basically the same as yesterday. I've increased the temp to ~70-72F now to try to increase activity. If I shine a light I still see stuff moving all around, but not a ton of bubble production/churning going on. Still a ~1/2 inch layer of foam.

It may be for whatever reason that this batch doesn't get very "violent." That's not a problem. Personally, if you have active fermentation (and you have for a while now), I probably wouldn't go much past 48 hours before adding the honey.

 

[TheMadKing]

The only "harm" in letting it go longer is that once the cells have been made, they start to die (they do that in the smack pack also), and the die-off happens faster at higher temps. Once the starter is finished, it's best to refrigerate it, if it won't be used right away. And if the yeast floccs out, you can decant, which as I type this I see you're mentioning in a new post.

We've already debated this a bit, and not trying to start an argument, but just a minor difference of opinion here: by letting a starter go too long and "finish out" you are creating a bunch of yeast cells that will have already used up much of their oxygen stores, so you are better off to put the starter in the refrigerator at maximum activity. (usually this occurs at about 12 hours for me, but sometimes longer depending on the strain and viability).

Also, yeast cells don't die quite that quickly, they go dormant and flocculate to await better days with more sugar and only after remaining dormant for a long period of time (new evidence from Jamil and others is showing that this is on the order of weeks), do they actually die.

@OP All of that said - if you're new to brewing and new to starters, just let it finish out at VikeMan says. It is not optimal, but it's functional, and easy, and you can refine your practices later if you choose to. On the order of "things to worry about in brewing" letting your starter finish out or not is down around a 3/10

 

[VikeMan]

We've already debated this a bit, and not trying to start an argument, but just a minor difference of opinion here: by letting a starter go too long and "finish out" you are creating a bunch of yeast cells that will have already used up much of their oxygen stores, so you are better off to put the starter in the refrigerator at maximum activity. (usually this occurs at about 12 hours for me, but sometimes longer depending on the strain and viability).

I'll just say that the oxygen that the yeast will need for replenishing cell wall material for division for the main fermentation is provided by oxygenating the main beer wort. And they don't need oxygen while dormant in the fridge.

Are you perhaps thinking of glycogen reserves? Yeast start producing these reserves when they start to run out of sugars. So I'm not so sure that they wouldn't have better reserves if allowed to finish out before refrigerating.

ETA: I'll be happy to change my opinion on that if there is good research to the contrary.

 

[TheMadKing]

I'll just say that the oxygen that the yeast will need for replenishing cell wall material for division for the main fermentation is provided by oxygenating the main beer wort. And they don't need oxygen while dormant in the fridge.

Are you perhaps thinking of glycogen reserves? Yeast start producing these reserves when they start to run out of sugars. So I'm not so sure that they wouldn't have better reserves if allowed to finish out before refrigerating.

ETA: I'll be happy to change my opinion on that if there is good research to the contrary.

Yes by "oxygen stores" I was referring to glycogen stores and their synthesized sterols in simplified terms.

Yeast Storage | Wyeast Laboratories - this implies (doesn't directly state - that glycogen stores are USED when the yeast run out of sugars, not produces). Therefore by letting a starter run out of sugar, you end up with yeast prematurely tapping into theri glycogen reserves. You will also have produced a higher number of yeast generations, and each generation results in thinner cell walls (depleted sterols) due to budding. So the theoretical "best starter you could make" is by reaching the highest cell density possible, in the fewest generations of yeast possible, with some sugar remaining in solution, and then making all the yeast go to sleep until winter is over.

Edit: Here is another very very good article that is worth a read no matter your knowledge level of yeast biomechanics The Biochemistry of Yeast - Aerobic Fermentation | MoreBeer

 

[saeven]

These are all things I will probably care about in 6-12 months, but are way over my head at the moment haha.

I just added the pound of honey at ~47 hours post-pitch. Should I take another OG reading, or wait until I see that all of the honey has been mixed in.. Because right now I see it all on the bottom.

 

[VikeMan]

Yeast Storage | Wyeast Laboratories - this implies (doesn't directly state - that glycogen stores are USED when the yeast run out of sugars, not produces).

Yes, I agree the glycogen stores begin to be used (for energy) when the sugar runs out. That's true of any yeast whether it's in the fridge or on a stir plate. But the sugar needs to be almost out before the yeast start to make them. It's just as valid to speculate that if you don't get to the point where they make reserves, i.e. you cut your starter off too soon, there won't be any glycogen stores. There will still be sugar in the environment, but will cold, dormant yeast use it? They haven't metabolized it, and now they are dormant, and it's mostly not in the cells.

Edit: Here is another very very good article that is worth a read no matter your knowledge level of yeast biomechanics The Biochemistry of Yeast - Aerobic Fermentation | MoreBeer

I'm quite familiar with that article, but I usually hesitate to recommend it to anyone, because there are are some facts in there that are doubtful at best. For example, there's a bit about avoiding O2 after the beginning of fermentation (good advice), because that will keep the beer from turning sour (ummmm).

 

[TheMadKing]

I'm quite familiar with that article, but I usually hesitate to recommend it to anyone, because there are are some facts in there that are doubtful at best. For example, there's a bit about avoiding O2 after the beginning of fermentation (good advice), because that will keep the beer from turning sour (ummmm).

He was referring to the fact that yeast are capable of producing acetic acid in the presence of ethanol and oxygen.

Whether that would turn a beer sour to the human taste buds is dependant on several factors. But he's not factually wrong that this metabolic pathway exists.

Edit: in an effort to stay on topic and help OP with his problem, I am not fundamentally disagreeing with your advice and I will leave it at that. I don't feel that an argument based on terminology and semantics, nor the fact that neither of us evidently have a thorough understanding of what's the correct answer here, is helpful to the OP. I'm sure we both make great beer so at the end of the day this doesn't matter one bit

 

[VikeMan]

I just added the pound of honey at ~47 hours post-pitch. Should I take another OG reading, or wait until I see that all of the honey has been mixed in.. Because right now I see it all on the bottom.

I don't see much point in taking a gravity reading after adding fermentables to an "in progress" fermentation. There's really nothing useful it would tell you. But it a good idea to calculate an "effective OG" using your original OG reading and adding the impact of the honey to that. That "effective OG" will serve as your starting point for calculating ABV when fermentation is finished.

 

[TheMadKing]

These are all things I will probably care about in 6-12 months, but are way over my head at the moment haha.

I just added the pound of honey at ~47 hours post-pitch. Should I take another OG reading, or wait until I see that all of the honey has been mixed in.. Because right now I see it all on the bottom.

Sorry about that, didn't mean to take this to technical town in 0 seconds

There's not much point in taking another gravity reading when adding honey post fermentation as it doesn't tell you much that's useful.

If you're interested in ABV, can back calculate your total gravity points put into the fermenter (measured OG + gravity points from honey shown in BeerSmith or brewers friend) and then measure your final gravity. It'll get you close.

On the fact that all your honey is sitting on the bottom, I don't have any specific experience with this, but I think its a problem because the yeast can't ferment concentrated honey like that. It needs to be mixed into solution. I'm hesitant to recommend stirring because it will mix in lots of oxygen, but that's probably your best bet here. Others may have better advice for you.

 

[VikeMan]

He was referring to the fact that yeast are capable of producing acetic acid in the presence of ethanol and oxygen.

Whether that would turn a beer sour to the human taste buds is dependant on several factors. But he's not factually wrong that this metabolic pathway exists.

"Therefore, one reason brewers try to avoid aeration after fermentation has begun is to prevent their beer from turning sour."

Have you ever experienced a Sacch beer that was soured via oxidation? As I said, I'm familiar with the article and frankly I doubt that pathway ever happens in Sacch fermented beers. I don't know what inhibits it, but it just doesn't happen. But apparently the author thinks it does.

 

[TheMadKing]

"Therefore, one reason brewers try to avoid aeration after fermentation has begun is to prevent their beer from turning sour."

Have you ever experienced a Sacch beer that was soured via oxidation? As I said, I'm familiar with the article and frankly I doubt that pathway ever happens in Sacch fermented beers. I don't know what inhibits it, but it just doesn't happen. But apparent;y the author thinks it does.

It requires A LOT of oxygen and a high alcohol percentage (think 5 gallons of fermented barleywine on a stir plate) alcohol is converted to acetic acid 1:1.. it's one way to make malt vinegar actually

 

[saeven]

Yeah so the honey is now at the bottom of the “trap” thing on the fermzilla.. so stirring isn’t really even an option. Guess we’ll just have to wait and see

 

[TheMadKing]

Yeah so the honey is now at the bottom of the “trap” thing on the fermzilla.. so stirring isn’t really even an option. Guess we’ll just have to wait and see

I've never used a fermzilla, can you pull the trap off and retreive the honey?

You could dilute it with preboiled water and dump it back in the top

 

[saeven]

I definitely could do that. But wouldn’t it just go back to the bottom? You think I should stir it while I pour the honey back in?
Everything I’ve read has always said “don’t stir!” Post-pitch so if you guys think I should re-Pour the honey while mixing, I will!

 

[VikeMan]

I definitely could do that. But wouldn’t it just go back to the bottom? You think I should stir it while I pour the honey back in?
Everything I’ve read has always said “don’t stir!” Post-pitch so if you guys think I should re-Pour the honey while mixing, I will!

My advice would be to leave it alone for a while. Or maybe gently swirl the fermenter without opening it.

I've never had a fermentation-added honey not ferment. Some mead makers have even intentionally not mixed their water and honey, just to see what would happen. The honey dissolves slowly but surely and the yeast have no problems finding it. The only thing that concerns me just a little bit is the fact that it's in the collection container, which reduces the contact area. Still, I'd let it ride at least a day or so before deciding to do anything drastic.

 

[TheMadKing]

My advice would be to leave it alone for a while. Or maybe gently swirl the fermenter without opening it.

I've never had a fermentation-added honey not ferment. Some mead makers have even intentionally not mixed their water and honey, just to see what would happen. The honey dissolves slowly but surely and the yeast have no problems finding it. The only thing that concerns me just a little bit is the fact that it's in the collection container, which reduces the contact area. Still, I'd let it ride at least a day or so before deciding to do anything drastic.

Patience is never bad advice