Calculating gravity and estimating required yeast cells for yeast starter

[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

 

[saeven]

I could also tonight close off the bottom trap (has all the honey and some yeast), unscrew it, pour it back in the top, and then reattach the bottom trap. That at least, would give the yeast more surface area to interact with the honey.

 

[saeven]

^And keep the bottom closed/not let anything in there for a bit until at least krausen is mostly done

 

[VikeMan]

You could do that. Personally, I'd give it time first. I don't think anything bad is going to happen while you wait.

 

[TheMadKing]

You could do that. Personally, I'd give it time first. I don't think anything bad is going to happen while you wait.

Agreed that there's no harm in waiting - but if you do that the honey will just settle to the bottom again. If it were me, I would mix it with some water and boil it to put it into solution, and then cool it and dump it in the top

 

[VikeMan]

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

Somehow I missed this post before. I have never made malt vinegar before, but everything I've read says that it relies on acetobacter, either added as "mother" or from the air. If you've got a reference that talks about Sacch yeast making the acetic acid in malt vinegar, I would appreciate it.

 

[TheMadKing]

Somehow I missed this post before. I have never made malt vinegar before, but everything I've read says that it relies on acetobacter, either added as "mother" or from the air. If you've got a reference that talks about Sacch yeast making the acetic acid in malt vinegar, I would appreciate it.

https://link.springer.com/article/10.1007/s11274-004-4516-y
So I think you're actually right about malt vinegar, most of the Sacch yeasts that produce acetic acid are wine yeasts

https://www.frontiersin.org/articles/10.3389/fmicb.2013.00033/full#h3
This one is just interesting in general

 

[saeven]

Both of you seem to know A LOT about brewing. Is this from just years of homebrewing? #goals

 

[VikeMan]

Both of you seem to know A LOT about brewing. Is this from just years of homebrewing? #goals

Too many years. But I also read a ****tun of studies, do a little consulting for comm'l breweries, and a few other things to try to keep up.

 

[saeven]

I could see myself semi-retiring and trying to open a brewery in like 20 years haha.

 

[TheMadKing]

Both of you seem to know A LOT about brewing. Is this from just years of homebrewing? #goals

Been brewing since 2008 or so, I'm an engineer and general information-a-holic, so most of what I've picked up has been from reading studies, books, articles, and this forum. I am good friends with a couple of pro brewers who I like to learn from, and sometimes help troubleshoot at their brewery, which helps.

Just your average idiot who really likes to try to learn stuff, mostly unsuccessfully

 

[saeven]

I am also a ChemE.. So this is right down my alley.

 

[VikeMan]

I am also a ChemE.. So this is right down my alley.

As a ChemE and aspiring brewer, you might went to check out "The Chemistry of Beer: The Science in the Suds" by Roger Barth.

There's another fairly popular book on brewing chem, which I won't name here, but it's horrible.

 

[ike8228]

As a fellow engineer I can tell you this is a hobby that won’t quit. As the saying goes, the more you know...the more you realize you don’t know Jack. I find myself looking something up and find 3 new things to research. Effectively back peddling. I would say don’t dwell on all these very specific details yet. It will never be fully understood. The best thing to do is focus on one thing at a time or two. Learn, practice, get good at it then learn a new thing or get a new piece of equipment to take the next step. Too many steps too quick, you could burn your self out and give up because if you make a mistake there are too many variables for you to know exactly what did what. I would recommend only trying something new every two batches of the same/similar style/recipe. More the better. You could do something. ‘Exactly’ the same way two or three times in a row, but have different tasting beer. Just the time yeast was packaged, or time of the season or where (same ‘brand/name/style’) hops were harvested. Don’t think you need to learn everything right now. Enjoy what you make, or try any way, and take it a step at a time.

 

[saeven]

I just noticed today that the liquid in the trap is a much different color than the liquid in the top part of the fermentor. I decided to take a hydrometer test, to which I got a 1.01 reading.

If I estimate my OG at ~1.055, (1.055-1.01)*131= 5.9%

What do I do now? I tasted it.. Not particularly tasty, but it is warm so that could be it. Do I bottle now?

 

[VikeMan]

I just noticed today that the liquid in the trap is a much different color than the liquid in the top part of the fermentor. I decided to take a hydrometer test, to which I got a 1.01 reading.

If I estimate my OG at ~1.055, (1.055-1.01)*131= 5.9%

What do I do now? I tasted it.. Not particularly tasty, but it is warm so that could be it. Do I bottle now?

So, I think we estimated 1.055 based on the LME used and your target volume. You need to add the impact of the honey to that. If you added a pound, that would increase the effective OG in your batch size by about 10 points, so figure 1.065 effective OG.

Now we're at OG 1.065, FG 1.010, ABV 7.2%.

I'd recommend waiting 3 days and measuring again, to make sure the FG is stable. If it is, and if there are no off flavors (like green apple or buttery), then I would bottle.

 

[John Coo's Brews]

I could see myself semi-retiring and trying to open a brewery in like 20 years haha.

I'm 20 years ahead of you, also a ChemE, and can highly recommend your aspirations. Not yet to the "open a brewery" stage, and still have a lot to learn, but it's been in the back of my mind for a while now.

@VikeMan, @TheMadKing - enjoyed reading your posts, as well as others on other threads. Always good advice.

 

[saeven]

@TheMadKing , just read this "Nobody's going to drink your beer and tell you it tastes like you have low efficiency." That's a very good point that I'll remember

Also, what is a "tropical stout?"

 

[saeven]

Update!

I took another hydrometer reading yesterday (3 days after the 1.01 reading) and I got 1.01 reading again. So I decided to bottle today.

I cleaned 24, 22oz bottles with PBW and StarSan along with the caps, and my beer siphon. I was having serious issues with the beer siphon while practicing in the bucket of starsan. I decided it must be the fact that I only had like a foot of tubing connected to the siphon. Went to Lowe’s, bought 20 feet of tubing and cut a 4 foot section off. And boom: works wonderfully now.
I first boiled ~4 oz of corn sugar in 2 cups of water, let it cool, and then added it to the bottling bucket. I siphoned all of the beer into the bucket (assuming it would all mix together during this process) and then bottled and capped. Bottling and capping was a lot easier than I expected.

I ended up getting 20, 22oz bottles so that’s about 3.3G. I have it stored in our pantry on the floor upright and will plan on keeping there for 3 weeks! Should I test one before then or just keep them there til they’re done carbonating and then put in fridge?
Overall today except for my siphon issues, it went pretty smoothly. I didn’t get any trub/yeast into the bottling bucket either so was pretty happy with that.

Now for clean up

 

[VikeMan]

I have it stored in our pantry on the floor upright and will plan on keeping there for 3 weeks! Should I test one before then or just keep them there til they’re done carbonating and then put in fridge?

Entirely up to you. Personally, especially with a high-ish gravity beer, I'd leave them alone for a while. But it won't hurt anything to try one before they are fully carb'd.

 

[TheMadKing]

@TheMadKing , just read this "Nobody's going to drink your beer and tell you it tastes like you have low efficiency." That's a very good point that I'll remember

Also, what is a "tropical stout?"

Tropical stout is a stout made mostly in the carribean as an attempt to brew foreign export stout with local ingredients. Specifically the difference is that they usually have a high percentage of dark sugar and are fermented warm with a lager yeast. It shoild be fruity, with very smooth roast, high abv, dark/dried fruit character, and very enjoyable on a hot day. It goes great with Jamaican jerk chicken and is one of my favorite beer styles.

The one I had on tap actually took 2 gold medals this spring and I'm going to be brewing it again pretty soon.