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Thread: Lets talk about the math please.

01012015, 01:47 PM #1
Lets talk about the math please.
So I have made around 25 gallons of mead since I started on this adventure near the end of October. In that time I have been very busy learning but relied on other recipes or asked for help on the numbers piece. I have, for now, enough handle on process and ingredients that I'm now ready to learn how to do the math. Our there links or threads that can explain this piece?
I'd like to make something besides a JOAM that would stop fermenting before it runs dry. Everything taste so much different if it went dry in ferment and I'm thinking if they croaked before it went dry that process would leave better flavors of the original ingredients.
For instance... I don't know how to figure how many points a yeast should eat before they die from intoxication, in hopes of leaving some RS. I don't know what a FG might be if it started at X point, and used a yeast with X alcohol tolerance.
I'm not sure how to figure a SG when some of the sugars are still in the body of fruit rather than in liquid form. I don't know how to accommodate points when added when step feeding.
I expect, that for those who would be inclined to teach me these things, a real life example ( a story problem ) so to speak would be best. I would like that help but would like to have a chance to get some exposure in linear form prior to the "real life" lessons.
Thanks7 out of 4 people have a hard time using their hydrometer!

01012015, 03:16 PM #2
I use the mead calculator to do most of that.
Take the cranberry mel I just started. I used the calculator to figure out how much sugar might be in the cranberry juice based on its SG.
I use it to figure out how much sugar would be left in the mead if <fill in the blank> or how much honey or other sugar source I need to add to get to <fill in the blank> ABV, etc.
I had one traditional where I had added enough honey for 16% ABV. I tasted it at 14%, and it was exactly what I was looking for. So I cold crashed it for a week or two and then racked onto stabilizing chems. It turned out exceedingly well and aged quickly. The yeast never awoke, there was very little burn, and it was clear as hell in no time.
Now that's not exactly the same as what you were asking about, but it's close.
The problem with letting the yeast get to their alcohol limit is multifaceted....
First, the yeast may not have read the datasheet and might not know they're supposed to die at xx% and may either stop short or go past it.
Second, when yeast gets close to its tolerance, it can/will often start throwing fusils and other off flavors, some of which may age out, some which may not.
Hope this helps at least some,
JoeIntelligence Is Knowing That A Tomato Is A Fruit
Wisdom Is Knowing Not To Put It In A Fruit Salad

01012015, 05:10 PM #3Got Mead? Patron
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I guess I may be a bit of a contrarian. The idea of wanting the yeast to croak and so leave enough residual sugar seems to me a little like deliberately stalling your engine to stop the car rather than using your breaks... If you know how much honey is in your must then you know exactly how much alcohol the yeast can make. You simply allow the yeast to finish its job, you stabilize the mead using Kmeta and ksorbate in tandem and then you add precisely as much sweetener as you prefer. The yeast may be guaranteed to ferment up to say 14 % ABV but that figure has some tolerance built in. Some of the yeast may collapse like a decrepit old codger at 12% and some may still be youthfully vigorous at 18% . Pick your preferred ABV, Mix enough honey and water (or apple juice or beer etc to reach that ABV and sweeten the mead you made.
Calculating the total ABV when you step feed is a little complicated but to determine your ABV in general you subtract the final gravity reading from the first gravity reading and multiply by (I use) 131. I don't add anything to compensate for figures below 1.000 as I think (and I may be wrong) that they are already counted in that 131(so a mead that started at 1.090 and ended at 1.000 has an ABV of about 11.8%. I'd call that 12% and be done with.
If you step feed, I would simply use the rule of thumb (others on this board may disagree with my RoT) that 4 oz of honey in 1 gallon of water increases the SG of that gallon by 10 points (or 1.010). It will increase the SG of 5 gallons by 2 points (or 1.0002) You add those additions to the starting gravity (so say you were making one gallon and you started with a must of 1.090 and added another 4 oz of honey half way through the fermentation, your nominal starting gravity would have risen to 1.100. Add another 4 oz the next day and the nominal starting gravity would be 1.110. I say, nominal, because the volume has also increased by the added honey but if you are an amateur mead maker and we are talking about small quantities and taxes are not an issue  for all intents and purposes your mead will have an ABV of 110 x 131 or about 14 15 % whether you call it 13 or 14 or 15 percent is neither here nor there... is it? It ain't 5 percent  and so similar to a beer, and it ain't 25%  or more like a spirit).Last edited by bernardsmith; 01012015 at 05:28 PM.

01012015, 10:14 PM #4
Putting the honey up front and letting the yeast die and having a sweet mead is fine as long as you don't want an exact final gravity each time you do a specific recipe. The yeast stop when the yeast stop, max alcohol tolerance is a good guestimate but yeast will go higher or lower. I do it all the time, and then will tweak possibly a little at the end by blending sweeter and drier meads...doing things by tatste. If you want a specific end gravity chemicals, or cold crashing and filtering are your best bets...
Bees stole my signature file!

01022015, 06:54 AM #5
Lets talk about the math please.
I do all my meads this way. Never backsweetened yet. Though many ppl say they can't make it work, so YMMV.
Key points.
 use metric
 magic number = 135
 1.000 sg = 1 kg/litre
That said.
I start using a yeast with a tolerance of 14%
14/135 = 0.104
So this yeast, (on a good day) will cause a drop of 104 points.
As such I would make my mead up to 1.124 gravity as I like my mead to finish strong 1.020.
Honey on average has an SG of 1.400
Water 1.000
So to achieve 1.124 I do the following.
Take the desired finish and the honey sg as a difference from the water SG.
1.124  1.000 = 0.124
1.400  1.000 = 0.400
124/400 = 0.31 litres water
0.31*1.400 = 0.434 kgs honey
So I need 690 ml water and 0.434 kg honey
(You can also get honey weight by calculating desired SG  water weight)
1.1240.690 = 0.434
I always to this to make sure I'm right.
Now, a 1 gallon batch? That's 3.8 litres if it's a US Gal.
So
3.8 * 0.69 = 2.6 litres water
3.8 * 0.434 = 1.65 kgs honey
Remember this is just an estimate because all honey is different, so make sure you use a hydrometer. I use this as a 'buying guide' to make sure I have enough honey.
So... Hope that was what you wanted.Mae'r teithiau golau ceffyl eto

01022015, 06:59 AM #6
What I've done there at the end, is basically used a Pearson square.
See this site. http://www.northtexaswinemakers.org/...ons_square.pdf
They talk of adding wine and syrup to get a baume.
It's the same principal .
It will also help you if you start with Apple juice and want to boost it.Mae'r teithiau golau ceffyl eto

01022015, 08:49 PM #7
So... Hope that was what you wanted.[/QUOTE]
Thank you. I will spend some time chewing on that tomorrow7 out of 4 people have a hard time using their hydrometer!

01022015, 09:04 PM #8
I never went to Math School, but it sounded good to me.
Intelligence Is Knowing That A Tomato Is A Fruit
Wisdom Is Knowing Not To Put It In A Fruit Salad

01022015, 11:00 PM #9
Math, my old enemy, we meet again!
What kudapucat wrote!Bees stole my signature file!

11172016, 01:26 AM #10Larva
 Join Date
 Oct 2016
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Since this thread is over a year old and I think Squatchy got the question answered I'll add a new math question to this thread. I am trying to work out my recipes mathematically, and math is not my strongest trait. My interest is stemming from the fact that initially much of the sugars are 'tied up' in the fruit, in the case of melomels, and the OG on the hydrometer can only reflect those sugars in suspension (unless I am woefully missing something). During fermentation, those sugars should become available but not displayed as part of the original OG. What I'm trying to do is work out an O.G. estimate (I add emphasis to the term "estimate") based off any recipe. Calculations based off estimated sugar content of fruit (by weight) and Honey (by weight), and any other additions  just like calculating TOSNA 2.0  but then calculating based off those Total sugars to estimate what the OG should be. I feel confidant there's a formula out there for this. I understand there's a mead calculator that likely works all this out for us but I'd prefer to know the calculations behind it. Anybody have that formula to share?

11172016, 10:50 AM #11Egg
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I guess you could find the sugar contents of your fruits by doing something like that (if you like to experiment) :
 take 100g fruits
 add 100g water (i.e. 100ml)
 mix to a fine paste
 boil for a few min to sterilize
 add water to compensate for evaporation, in order to get back to 200g total
 let it sit in a closed jar for a few days
 take a sample of the liquid with an hydrometer
 multiply the gravity by 2 (i.e 1.02 becomes 1.04) to find the gravity added by the fruit.
Or you could just find the info online :
https://en.wikipedia.org/wiki/Fructose
or I found one very complete, but only in french (didn't found it in english, blame my googlefu) : https://fr.wikipedia.org/wiki/Compos...lle_des_fruits
Knowing the sugar content per 100g, you can find the total sugars added by the fruits in your must, convert to Brix and then to density.Last edited by Krapou; 11172016 at 11:11 AM.

11172016, 10:27 PM #12Got Mead? Patron
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The US govt dept of agriculture (USDA) publishes the nutritional content of all fruits and vegetables. The figures are obviously averages but they are very useful. So, for example, the data they provide tell you how much sugar is likely to be in a "unit" of apples or strawberries or pears or mangoes etc... If you know that value and you know how many units of the fruit you are using per gallon then you can guestimate the SG that that fruit will add to the must.

11182016, 01:32 AM #13Larva
 Join Date
 Oct 2016
 Posts
 24
Krapou and bernardsmith, thanks for your input. I have the average percentages per unit of fruit worked out. I have used the same spreadsheets/tables on previous batches to calculate the sugar content when figuring the feedings for TOSNA 2.0. I kept trying to find a way to calculate straight from g/L (sugar) to SG and just ended up frustrated. The part I was missing was converting the total sugars to Brix, and then converting that result to SG. When checking against past recipes it doesn't pencil out in all cases, but it comes remarkably close for most.
I want to be able to estimate what the OG of a recipe will be as I plan it. If I want to rebalance ingredients to maximize flavors, then I can recalculate and still have a reasonable expectation of what the OG will be. This may affect yeast selection (abv tolerance/attenuation) and allow me to forecast when I may need space available for coldcrashing. I also just want to attempt to bring greater consistency to my mazing efforts.
Thanks for all the help!

11182016, 09:59 AM #14Piping Queen
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 Aug 2016
 Location
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Dude Google is beautiful friend:
1) Converting sugar to brix: (halfway down the page) http://www.meadmaderight.com/tosna.html.
2) Converting Brix to Specific Gravity: http://www.winninghomebrew.com/spec...ytobrix.html.
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