Calculating ABV from fruit in secondary?

[gatorforty]

Hey Guys,

Trying to figure this out, but I can't find a source.

I brewed an Apricot Wheat ale recently, just bottled it.

I waited until 5 days ferm in the primary before racking to a secondary on top of 5 lbs of pureed apricots. It was a 2.5G batch.

It started at 1.052, and I took a reading of 1.007 before racking to the secondary. I'm assuming it was pretty close to done, that's about what my target FG was.

After the secondary, which did have some pretty active visible fermentation, I took a sample of 1.009 before I bottled.

How do I calculate the ABV, and is there anyway to determine how much of the Apricot fermented?

Thanks,

Ron

 

[ddrrseio]

the easiest way to do this is to use a refractometer AND a hydrometer.

post-ferment refractometer readings are useless by themselves, but when paired with a hydrometer reading (either OG or FG), you can learn the adjusted gravity.

1) take the initial gravity reading when you pitch your yeast (OG).
2) take another one when the primary fermentation ends (not necessary but good for your records).
3) pitch fruit and measure the FG with both the refractometer and hydrometer.
4) use the calculator below to find your new, adjusted OG.

http://onebeer.net/refractometer.shtml

i am not sure the author of this tool had this in mind or envisioned its use this way, but it works well for this. using the refractometer brix reading, keep adjusting the OG until it spits out the correct FG as measured with the hydrometer. the difference in OG1 and OG2 can be attributed entirely to the fruit addition.

 

[gatorforty]

Thanks. I thought about taking a reading after I racked onto the fruit, but since the pureed apricot was in the bottom of the secondary carboy when I racked, and I was advised NOT to mix/stir/etc, I figured the reading would be really far off.

 

[ddrrseio]

i think this way is easier, personally

 

[VikingChrisColby]

Alternately, you can look up the percentage of sugar in the fruit and calculate it that way. Multiplying the % sugar times the weight of your fruit will give you the total amount of sugar added. Plug that into your brewing calculator as sucrose and that will give you an estimate.

Chris Colby
Editor
beerandwinejournal.com