Weighing your BOMM

[renrutle]

I'm on my third batch of BOMM in half as many months.

See this thread for the original recipe and many great notes on making a wonderful mead.
https://www.homebrewtalk.com/forum/threads/brays-one-month-mead.429241/

During the first two I began think about how to keep track of when to make the 2/3, & 1/3 sugar break nutrient additions. I had trouble inserting and removing the hydrometer (fat fingers) and the calculations with my refractometer are suspect. I did some quick calculations on the fermentation chemistry of sugar to CO2 and ethanol and realized that the CO2 produced is about 1/2 the weight of the sugars that are fermented. I should be able to detect this weight loss with my new 5 kilogram digital scale. From other sources I noted that honey is mostly sucrose and is about 90% fermentable. This coupled with a lot of information from the thread linked above I came up with the following plan.

Weigh all the ingredients and equipment at the start of fermentation.
Re-weigh the fermenter every day after de-gassing the mead.
Add additional nutrients (also weighed) at the calculated 2/3, & 1/3 sugar break weights.

Initial weights in grams.

Item --------WT ---- Total
Jug ------- 1381 - 1381
Honey ------ 1630 - 3011
Water ------ 2528 - 5539
Nutrients --- 0005 - 5544 <-- I will be using this as my initial weight. I lift the airlock prior to weighing.
Airlock ----- 0038 - 5582

The yeast weight is included with the water. I didn't get a separate weight for the yeast. I think I really only need the honey weight and the final weight to make use of this process.

1630 grams (~3.6#) of honey in 1 gallon gives a SG of 1.139. (A bit more that I wanted but the HBS got a little aggressive when filling my tubs with honey.) From Dr. Denards notes, Wyeast 1388 will ferment about 120 points of this or (120/139) * 1630 = 1407 grams of the honey. At 90% fermentability this means that 1407 * 0.9 = 1266 grams of sucrose will be converted to CO2 and ethanol.

Sucrose is C12H22O11 with a molecular weight of 342.3 grams/mole
4 molecules of CO2 will be produced for each of molecule of sucrose consumed by the yeast. The molecular weight of CO2 is 44 grams per mole so 4 * 44 = 176 grams of CO2 is produced for every 342.3 grams of sucrose. 176/342.3 = 0.51

Fermenting 1266 grams of sucrose will produce 0.51 * 1226 = 651 grams of CO2.

At the 2/3 sugar break, 1/3 of the sugar has been consumed and 1/3 of the total CO2 has been produced.

1/3 * 651 = 217 grams of CO2 produced. The fermenter should weigh 217 grams less at this point.

Similarly at the 1/3 break, 2/3's of the sugar has been consumed and 2/3's of the total CO2 has been produced.

2/3 * 651 = 434 grams of CO2 produced. The fermenter should weigh 434 grams less at this point.

Caveats:
I understand that I have made a few assumptions not limited to the following.
Honey is mostly sucrose and 90% fermentable by weight.
Any monosaccharides present that are fermented will throw off my 0.51 ratio of CO2 produced. Glucose gives a ratio of 0.49.
I can remove most/all the CO2 prior to weighing. (1 volume of CO2 per gallon weighs ~7 grams)

My 6 step weighing process is as follows.

1. Turn on and tare the scale.
2. Place fermenter on scale.
3. Lift airlock.
4. Record weight.
5. Replace airlock.
6. Return fermenter to counter.

So far I find this easier than having to sanitize, insert, read, and remove my hydrometer.

(Edit: 3-26-2019 These ratios/weights seem to be off in relation to when Bray makes his nutrient additions. See posts below for more details.)

Weights of fermenter for nutrient additions are:
2/3 : 5544 - 217 = 5327
1/3 : 5544 - 434 = 5110

Fermentation temp on counter is 68°F.

My data so far.

Date - Weight
02-20 - 5544
02-21 - 5523
02-22 - 5503
02-23 - out of town today
02-24 - 5416
02-25 - 5392 - getting close to first addition.
02-26 - 5368
02-27 - 5347
02-28 - 5324 - I added 3 grams of nutrients this morning.
02-28 - 5325 - After degassing and adding nutrients.
03-01 - 5296
03-02 - 5275
03-03 - 5262
03-04 - 5249
03-05 - 5238
03-06 - 5227
03-07 - 5216
03-08 - 5206
03-09 - 5196
03-10 - 5186
03-11 - 5177
03-12 - 5168
03-13 - 5159
03-14 - 5150
03-15 - 5142
03-16 - 5134
03-17 - 5127
03-18 - 5120
03-19 - 5113 - Second nutrient addition
03-20 - 5108
03-21 - 5106
03-22 - 5104
03-23 - 5102
03-24 - 5101
03-25 - 5100

Will update with additional weights over the next several weeks. * -

 

[loveofrose]

Do you have Hydrometer reading at these points to confirm your theory is working? It would further provide evidence to your claim if they are spot on what your weight is showing. Just trying to help cut off any naysayers with data!

This is chemistry. If it doesn’t work, it’s because of a confounding factor. Such as CO2 dissolved into solution. In that case, it’s just about determining a fudge factor in your calculations (which your Hydrometer reading would help with).

 

[RPh_Guy]

I had trouble inserting and removing the hydrometer (fat fingers)

For my 1 gal batches I use a turkey baster to transfer a sample into my hydrometer tube. The top of the hydrometer is above the lip on the tube, so it's easy to remove.
Everything is sanitized so I pour the sample back into the carboy.

I agree with Bray ... Measuring weight is fine, but I'd still want to double check with a hydrometer reading, at least for the first batch to verify your calculations and that your scale is reasonably accurate.
I had too much beer to help with the math right at this moment.

Cheers

 

[NeverDie]

It might help if there's no oxygen skewing the results:

Unless you know of a way to account for that?

Or, perhaps it's just not significant?

It doesn't have to be dead nuts--just good enough for figuring out the sugar breaks. Seems like it would be good enough for that.

There was some discussion of using load cells to estimate it here: https://www.homebrewtalk.com/forum/...ight-of-fermentation-co2.660586/#post-8484259

Although I elected to go the TILT route, TILTs don't work well on a stir plate, whereas maybe a load cell still could (if mounted beneath the stir plate). Same for very small volume starters, where there wouldn't be enough liquid to float a TILT or even take a regular hydrometer reading.

 

[NeverDie]

I'm going to give this gravimetric approach a try. I'll hedge a bit though rather than run the risk of running into too low a nitrogen scenario.

 

[JimRausch]

I didn't notice in your 1st post: Are you accounting for an increase in yeast mass due to budding? Think about it- you sprinkle a small packet of yeast, and how much lees do you have at first racking? Quite a bit more than that little packet.

 

[Blacksmith1]

I don't think they can add more weight to your product, bit they may keep some in as all that is released os CO2.

 

[JimRausch]

Here's another potential problem with your theory. You say you're working with the theory that honey is mostly sucrose? References I've seen indicate that it's more like 35+% fructose, 30+% dextrose and only 1-2% sucrose.

 

[NeverDie]

These are good attempts to poke holes in it, so keep it coming.

I would be content to have a formula that translates loss of weight in grams into upper and lower bounds on how much of the honey has been digested. It would be interesting to see just how wide a spread it is, but until someone smarter than me does the analysis, I don't think I could even guess. Then I would pick the upper bound as the conservative figure when deciding when the sugar break has been reached. I'm betting the spread won't be too large (say 10% accuracy?) and it will be good enough for SNAP.

 

[papz]

If i can get this to post right.... this is a cut and paste from some thread i read long ago.
It might be of use to you here. (or not)


If you have an accurate scale and a 1 liter flask you can make a rough estimate of the ABV by weighing a sample.

At 77ºF ethanol has a density of 785 g/l and water has a density of 998 g/l.

This info plus a bit of math gives the following table for the weight of 1.00 liter of beer/cider/wine.

Weight
in
Grams - - - %ABV
998.2 - - - 0.00%
996.1 - - - 1.25%
993.9 - - - 2.50%
991.8 - - - 3.75%
989.7 - - - 5.00%
987.5 - - - 6.25%
985.4 - - - 7.50%
983.3 - - - 8.75%
981.1 - - - 10.00%
979.0 - - - 11.25%
976.9 - - - 12.50%
974.7 - - - 13.75%
972.6 - - - 15.00%
970.5 - - - 16.25%
968.4 - - - 17.50%
966.2 - - - 18.75%
964.1 - - - 20.00%
962.0 - - - 21.25%
959.8 - - - 22.50%
957.7 - - - 23.75%
955.6 - - - 25.00%


This table does not account for any other component of of the finished product such as unfermented sugars, proteins, hops oils, esters, etc.

YMMV (a lot.)

 

[renrutle]

Do you have Hydrometer reading at these points to confirm your theory is working? It would further provide evidence to your claim if they are spot on what your weight is showing. Just trying to help cut off any naysayers with data!

This is chemistry. If it doesn’t work, it’s because of a confounding factor. Such as CO2 dissolved into solution. In that case, it’s just about determining a fudge factor in your calculations (which your Hydrometer reading would help with).

While I don't particularly like the Nay Nay some people do.


</sarc>

I have not taken any hydrometer or other readings on this batch (Batch #3). When Batch #2 is done at the end of the week (started on Feb 7th) I plan to re-pitch the yeast on 2 new batches. Batch #3 should be done about March 22 and I plan to do the same.

 

[NeverDie]

While I don't particularly like the Nay Nay some people do.


</sarc>

I have not taken any hydrometer or other readings on this batch (Batch #3). When Batch #2 is done at the end of the week (started on Feb 7th) I plan to re-pitch the yeast on 2 new batches. Batch #3 should be done about March 22 and I plan to do the same.

I suspect capturing just four pieces of data (starting weight and OG and the terminal weight and FG) is all that will be needed to calibrate for future measurements.

 

[renrutle]

I didn't notice in your 1st post: Are you accounting for an increase in yeast mass due to budding? Think about it- you sprinkle a small packet of yeast, and how much lees do you have at first racking? Quite a bit more than that little packet.

My assumption on yeast growth is that once the airlock in in place the mass of the fermenter cannot increase. Nothing is added except nutrients that I weigh. Certainly the yeast will reproduce but any additional yeast mass will be offset by a decrease in some other component in the mead (sugar, O2, nutrients, etc.)

 

[renrutle]

It might help if there's no oxygen skewing the results:

This is certainly a possibility. I need to do more research on yeast metabolism and reproduction in aerobic and anaerobic conditions. It may be a wash but I don't know at this point. Certainly after the first few days it should be anaerobic and have moved into ethanol production.

 

[renrutle]

I'm going to give this gravimetric approach a try. I'll hedge a bit though rather than run the risk of running into too low a nitrogen scenario.

I had thought of this too. May need to add nutrients at an earlier weight than I initially estimated.

 

[renrutle]

Here's another potential problem with your theory. You say you're working with the theory that honey is mostly sucrose? References I've seen indicate that it's more like 35+% fructose, 30+% dextrose and only 1-2% sucrose.

The sugar composition does present a problem but I think it is minor. CO2 is 51% the weight of sucrose but only 49% the weight of glucose. I will try to run some numbers and see what the difference would be at the 2/3, 1/3 and FG stages.

 

[renrutle]

These are good attempts to poke holes in it, so keep it coming.

I would be content to have a formula that translates loss of weight in grams into upper and lower bounds on how much of the honey has been digested. It would be interesting to see just how wide a spread it is, but until someone smarter than me does the analysis, I don't think I could even guess. Then I would pick the upper bound as the conservative figure when deciding when the sugar break has been reached. I'm betting the spread won't be too large (say 10% accuracy?) and it will be good enough for SNAP.

I like the idea of a spread. It is kind of what I was attempting to come up with I guess. It is quite easy and fast (less that a minute) to measure the weight. Nothing to sanitize either.

I appreciate everyone's comments and suggestions.

 

[renrutle]

For my 1 gal batches I use a turkey baster to transfer a sample into my hydrometer tube. The top of the hydrometer is above the lip on the tube, so it's easy to remove.
Everything is sanitized so I pour the sample back into the carboy.

I agree with Bray ... Measuring weight is fine, but I'd still want to double check with a hydrometer reading, at least for the first batch to verify your calculations and that your scale is reasonably accurate.
I had too much beer to help with the math right at this moment.

Cheers

I guess I'll need to get a baster for my next set of data so I can correlate the SG with weight loss. How often to you measure the SG? I have read so much the last several days that I don't recall how often Bray suggested taking a reading.

 

[loveofrose]

I guess I'll need to get a baster for my next set of data so I can correlate the SG with weight loss. How often to you measure the SG? I have read so much the last several days that I don't recall how often Bray suggested taking a reading.

Since you are doing an experiment, I would leave the Hydrometer in the mead.

 

[NeverDie]

Since you are doing an experiment, I would leave the Hydrometer in the mead.

Come to think of it, doing that would be just a small fraction of the cost of buying a TILT! Hydrometers are cheap.

 

[renrutle]

It might help if there's no oxygen skewing the results:
View attachment 615410

Unless you know of a way to account for that?

Or, perhaps it's just not significant?

It doesn't have to be dead nuts--just good enough for figuring out the sugar breaks. Seems like it would be good enough for that.

There was some discussion of using load cells to estimate it here: https://www.homebrewtalk.com/forum/...ight-of-fermentation-co2.660586/#post-8484259

Although I elected to go the TILT route, TILTs don't work well on a stir plate, whereas maybe a load cell still could (if mounted beneath the stir plate). Same for very small volume starters, where there wouldn't be enough liquid to float a TILT or even take a regular hydrometer reading.

After reviewing some of my notes from a brewing chemistry class I took a while back I think the amount of CO2 produced is the same regardless of whether the yeast is in aerobic or anaerobic conditions. Glucose metabolism is a fairly complex process involving 10 intermediate steps. One of the last ones is the production of the compound pyruvate (C3H4O3). Two molecules of this compound are produced for every glucose metabolized. If oxygen is present the yeast uses pyruvate to reproduce which results in (among other things) one H2O and one CO2. If no oxygen is available the yeast instead produce one ethanol and one CO2.

Either way each glucose produces 2 CO2. Each sucrose would produce 4 CO2.

This article discusses human metabolism of glucose which produces lactic acid (same as lactobacillus) at the step where yeast would produce ethanol. Other than that difference, the chemistry is the same.

https://cnx.org/contents/nWir-Uwu@7/Carbohydrate-Metabolism

 

[NeverDie]

After reviewing some of my notes from a brewing chemistry class I took a while back I think the amount of CO2 produced is the same regardless of whether the yeast is in aerobic or anaerobic conditions. Glucose metabolism is a fairly complex process involving 10 intermediate steps. One of the last ones is the production of the compound pyruvate (C3H4O3). Two molecules of this compound are produced for every glucose metabolized. If oxygen is present the yeast uses pyruvate to reproduce which results in (among other things) one H2O and one CO2. If no oxygen is available the yeast instead produce one ethanol and one CO2.

Either way each glucose produces 2 CO2. Each sucrose would produce 4 CO2.

This article discusses human metabolism of glucose which produces lactic acid (same as lactobacillus) at the step where yeast would produce ethanol. Other than that difference, the chemistry is the same.

https://cnx.org/contents/nWir-Uwu@7/Carbohydrate-Metabolism

Good to know! Thanks.

 

[lump42]

I noticed in the initial weight set that it was only noted degassing the mead once. Based on my limited understanding of physics, the co2 is only escaping the liquid once it reaches saturation in the liquid. Without degassing it, some of the co2 will still be in solution and adding to the weight. I don't know how much it would throw off the theoretical calculations, I wouldn't think much but could be built into the any compensating factor.

Like others have said, I don't think it would need daily measures. But the starting and final would be where I would start to begin validation. I did similar thing when I started using a refractometer, double measuring to verify it was working in my set up.

 

[NeverDie]

I noticed in the initial weight set that it was only noted degassing the mead once. Based on my limited understanding of physics, the co2 is only escaping the liquid once it reaches saturation in the liquid. Without degassing it, some of the co2 will still be in solution and adding to the weight. I don't know how much it would throw off the theoretical calculations, I wouldn't think much but could be built into the any compensating factor.

Like others have said, I don't think it would need daily measures. But the starting and final would be where I would start to begin validation. I did similar thing when I started using a refractometer, double measuring to verify it was working in my set up.

In the OP he estimated that the weight of the dissolved (non-degassed) CO2 was 7g per gallon. If that's accurate (?), then maybe there's no need to degass before weighing. Instead, maybe just subtract 7g per gallon from the amount weighed? I suppose it might depend on your altitude and barometric pressure to some extent and temperature of the must, but not sure if those wrinkles are significant or not.

I can say that merely shaking the carboy to degass it, as I did this morning, only seems to drop the weight by maybe 1 or 2 grams per gallon. I guess the shaking approach isn't very thorough.

 

[lump42]

In the OP he estimated that the weight of the dissolved (non-degassed) CO2 was 7g per gallon. If that's accurate (?), then maybe there's no need to degass before weighing. Instead, maybe just subtract 7g per gallon from the amount weighed? I suppose it might depend on your altitude and barometric pressure to some extent and temperature of the must, but not sure if those wrinkles are significant or not.

I can say that merely shaking the carboy to degass it, as I did this morning, only seems to drop the weight by maybe 1 or 2 grams per gallon. I guess the shaking approach isn't very thorough.

Oops missed that. Well then if CO2 at saturation is 7g that's only a 0.1-0.2% of the total weight. Not a big impact then.

 

[renrutle]

In the OP he estimated that the weight of the dissolved (non-degassed) CO2 was 7g per gallon. If that's accurate (?), then maybe there's no need to degass before weighing. Instead, maybe just subtract 7g per gallon from the amount weighed? I suppose it might depend on your altitude and barometric pressure to some extent and temperature of the must, but not sure if those wrinkles are significant or not.

I can say that merely shaking the carboy to degass it, as I did this morning, only seems to drop the weight by maybe 1 or 2 grams per gallon. I guess the shaking approach isn't very thorough.

A 1-2 gram drop is what I experienced. From Bray's notes, if I remember correctly, degassing is helpful to keep the pH from getting too low. Dissolved CO2 produces carbonic acid. It is also important to degas prior to adding the nutrients so the mead doesn't explosively release any CO2 and make a mess. Degassing prior to weighing I don't think is necessary as the "extra" CO2 can be approximated to calculate the proper weight to add the nutrients.

Depending on your fermentation temp the dissolved CO2 is between 0.75 and 1.0 volumes. At 68F it is 0.85 volumes which should be 5.95 grams CO2. 1 gallon of CO2 weighs ~7 grams.

I think this "extra" weight should be fairly constant through out the fermentation. Per gallon of must, every 9.9 grams of sugar metabolized should produce a drop in SG of 1 point and ~5 grams of CO2. From my measurements so far there is a daily loss in weight of ~20 grams or a 4 points loss per day.

 

[NeverDie]

I'm currently using this method to manage the sugar breaks on seven small batches of mead--soon to be about a dozen. 4 of the 7 have passed their 1/3 sugar break, as measured by the method here, and so far all seems to be going well.

 

[renrutle]

I'm currently using this method to manage the sugar breaks on seven small batches of mead--soon to be about a dozen. 4 of the 7 have passed their 1/3 sugar break, as measured by the method here, and so far all seems to be going well.

I had too much beer to help with the math right at this moment.
Cheers

Your confidence in my math and chemistry/physics is noted.

As an engineer I am always looking to optimize a process. However, it takes many experiments to validate the accuracy of a hypothetical concept. Any notes you can add will be helpful.

 

[NeverDie]

I now have 17 different batches under management using this gravimetric method to judge when the 1/3 and 2/3 sugar breaks occur. All seems to be going smoothly. Weighing the jug on a scale is a lot faster than drawing a sample, and I can do it as often as I want without fear of contamination.

 

[Maylar]

I don't have a scale that'll weigh 60 pounds

 

[NeverDie]

I don't have a scale that'll weigh 60 pounds

I'm sure there are package scales that go that high. No sure about their resolution though.

I have a digital scale that can go to 22# at 1 gram resolution.
https://www.amazon.com/gp/product/B07HGR7V8Y/ref=oh_aui_search_asin_title?ie=UTF8&psc=1
A bit of a hassle, but you could use four of those and combine their measurements to weigh your 60 pounds and still get good resolution....

 

[NeverDie]

I'm guessing that weighing may also be a good way to judge when fermentation has completed. I assume no change in weight should mean fermentation has stopped? Again, much easier than taking gravity readings.

 

[NeverDie]

I posted this on another thread, but I'll post it here also because it shows the 17 bottles of mead (plus 2 more that will join them) that I've been managing using the weighing method as opposed to taking direct gravity readings.

You can see where I wrote the original weight on each of the bottles as well as the weight's that I computed for the first and second sugar breaks.

For these 3L bottles, I use a scale with 0.1g resolution and is repeatable, so I think that may be useful in deciding when fermentation has finished. i.e. if the weight seems pinned at a particular number for long enough, then I'm theorizing that means fermentation is completed.

 

[lump42]

I don't have a scale that'll weigh 60 pounds

How about 100-lbs capacity postal scale? Or if your not as worried about the resolution, a digital bath scale that reads out in lbs and kg, +/- 0.2lbs/0.1kg can be had for under $20.

 

[Maylar]

How about 100-lbs capacity postal scale? Or if your not as worried about the resolution, a digital bath scale that reads out in lbs and kg, +/- 0.2lbs/0.1kg can be had for under $20.

I was gonna say I'd rather use a hydrometer.. until I broke both of mine today

 

[Blacksmith1]

That sucks.

 

[lump42]

I was gonna say I'd rather use a hydrometer.. until I broke both of mine today

Missed wink, That does suck...

 

[NeverDie]

Sounds like a perfect opportunity to try the weighing method.

 

[NeverDie]

Today I started a new traditional mead using 71B in a 1 gallon jar. I have instrumented it with a TILT wireless hydrometer so that we can finally compare SG readings to weight lost and see how good our calculations have been. I weighed the honey that went into it to the nearest gram, and I weighed the entire jar, TILT included, to get a starting weight measurement. OG, as reported by TILT, is right on the money at 1.105 SG. I have two rounds of nutrient additions at the first and second sugar break that have yet to be done, so I'll measure the impact of those on weight also. I'll keep track of the weight measurements when I perform them and time and date stamp them so that they can later be compared with the TILT's SG measurements at the same time. At some point I'll post the data so that everyone can make their own comparisons if they want to and draw their own conclusions about how accurate (or not) this weighing method actually is.



@renrutle: where is Magnolia located? When I click on your locator, it gives a BestBuy store in Austin, Texas.

 

[Miraculix]

Today I started a new traditional mead using 71B in a 1 gallon jar. I have instrumented it with a TILT wireless hydrometer so that we can finally compare SG readings to weight lost and see how good our calculations have been. I weighed the honey that went into it to the nearest gram, and I weighed the entire jar, TILT included, to get a starting weight measurement. OG, as reported by TILT, is right on the money at 1.105 SG. I have two rounds of nutrient additions at the first and second sugar break that have yet to be done, so I'll measure the impact of those on weight also. I'll keep track of the weight measurements when I perform them and time and date stamp them so that they can later be compared with the TILT's SG measurements at the same time. At some point I'll post the data so that everyone can make their own comparisons if they want to and draw their own conclusions about how accurate (or not) this weighing method actually is.



@renrutle: where is Magnolia located? When I click on your locator, it gives a BestBuy store in Austin, Texas.

Very good, keep us posted!