Help figuring out ABV.

[BenLazarus]

I didn't have a way to measure the SG and was curious if theres a way to get a basic estimation on the ABV from the FG.

Primary -Started Jan 16th 2014

600g (1.32lbs) frozen and thawed peaches
1-Cinnamon stick
1-Clove
1-tsp fleischmann's bread yeast
26 Raisins
1.5 kg (3.3lbs) clover honey
water to 4L

Secondary - Feb 3rd 2014

Racked onto
1.2 kg (2.64lbs) frozen and thawed peaches
1/2 cup brown sugar
2 tsp vanilla extract
1-Campden Tablet
1/2tsp Potassium Sorbate

Third rack Feb 18th 2014
SG at third rack was 1.014

So really the question is...do you think my original FG was lower than 1.014 and then I back sweetened it with the sugar in secondary? It didnt seem like it was doing much fermenting in the secondary (which i tried to stop any from happening with the campden and potassium sorbate)

I also found a spread sheet and got a rough OG est of 1.134

3.3lbs of honey = ~.280 gal
~.625 gal of water
than an additional .1lbs of sugar from the 600 grams of peaches (aprox 8g of sugar per 100g of peaches. but thats also assuming 100% sugar extraction from the peaches) and also rounding out the volume to 1 gallon.

 

[Complete_Amateur]

I didn't have a way to measure the SG and was curious if theres a way to get a basic estimation on the ABV from the FG.

Primary -Started Jan 16th 2014

600g (1.32lbs) frozen and thawed peaches
1-Cinnamon stick
1-Clove
1-tsp fleischmann's bread yeast
26 Raisins
1.5 kg (3.3lbs) clover honey
water to 4L

Secondary - Feb 3rd 2014

Racked onto
1.2 kg (2.64lbs) frozen and thawed peaches
1/2 cup brown sugar
2 tsp vanilla extract
1-Campden Tablet
1/2tsp Potassium Sorbate

Third rack Feb 18th 2014
SG at third rack was 1.014

So really the question is...do you think my original FG was lower than 1.014 and then I back sweetened it with the sugar in secondary? It didnt seem like it was doing much fermenting in the secondary (which i tried to stop any from happening with the campden and potassium sorbate)

I also found a spread sheet and got a rough OG est of 1.134

3.3lbs of honey = ~.280 gal
~.625 gal of water
than an additional .1lbs of sugar from the 600 grams of peaches (aprox 8g of sugar per 100g of peaches. but thats also assuming 100% sugar extraction from the peaches) and also rounding out the volume to 1 gallon.

Honey 35 ppg * 3.3 = 115.5
4 lbs peaches (9% sugar) = 16.2
1/2 cup brown sugar (this is an estimate) = 9.9

1.1416 (seems high, but that's a lot of honey and fruit to a single gallon, so I wouldn't be surprised if it were quite close)

A little higher than your spreadsheet value, but you seem to have not counted all the peaches that your recipe appears to include (1.32 lbs primary and 2.64 lbs secondary). Most of the peach sugar will be consumed, but the actual OG is probably somewhere between the two figures.

 

[BenLazarus]

Thanks for the reply.

So say i added the peaches and brown sugar values from the secondary and used your OG value of 1.1416 and my measured FG value of 1.014

wouldn't that yield me an ABV of ~17%? isnt that quite high for just plain old fleischmann's bread yeast?

 

[bigmunchez]

If you have a refractometer and a hydrometer, you can measure the SG and the brix value of the finished beer and enter those values into a formula to calculate OG. Beersmith has the formula under 'refractometer', there's bound to be other calculators out there somewhere.

 

[Complete_Amateur]

Thanks for the reply.

So say i added the peaches and brown sugar values from the secondary and used your OG value of 1.1416 and my measured FG value of 1.014

wouldn't that yield me an ABV of ~17%? isnt that quite high for just plain old fleischmann's bread yeast?

16.7%, 90% apparent attenuation. It is high, but not entirely unheard of. The Campden and sorbate additions would likely prevent fermentation of the additional peaches and brown sugar, but these still make a contribution to the gravity. It is likely that the primary fermented dry, and the added fruit and brown sugar brought you back up above 1.0. Subtract the addition of 2/3 the peaches and the BS (~20 ppg) and you get .994.

I have never used a refractometer, but from what I understand, you need to compensate for alcohol content to get an accurate reading, which requires that you have the Original Gravity. Maybe this is accounted for, but I think it is also an estimate.

In any case, the taste is probably what matters most right?

 

[bigmunchez]

My understanding is that the formula uses the degree of discrepancy that the alcohol causes between the two readings to actually figure out the OG and ABV. So not really an estimation. Every time I've used beersmiths refractometer tools they seem pretty spot on. Anyway, its all irrelevant if you don't have one!!