Author Topic: sugar contribution for fruit in secondary  (Read 652 times)

Offline goschman

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sugar contribution for fruit in secondary
« on: March 25, 2014, 04:38:54 PM »
Trying to figure out how to adjust my ABV from adding fruit. Forgive me if this is a bad idea. The only thing I can think of is to take a gravity reading before and after adding the fruit. Any increase in gravity from the fruit would be added to the OG?
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Offline HoosierBrew

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Re: sugar contribution for fruit in secondary
« Reply #1 on: March 25, 2014, 04:58:12 PM »
Trying to figure out how to adjust my ABV from adding fruit. Forgive me if this is a bad idea. The only thing I can think of is to take a gravity reading before and after adding the fruit. Any increase in gravity from the fruit would be added to the OG?

It sounds counterintuitive, but you probably don't need to adjust it at all. Even though you get a second fermentation from fruit, ABV doesn't change much because fruit is mostly water. So the sugar that ferments into alcohol from the fruit gets diluted in turn by the fruit's water. When I make a fruit beer for my wife I don't even count the fruit toward abv.
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Offline goschman

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Re: sugar contribution for fruit in secondary
« Reply #2 on: March 25, 2014, 05:16:31 PM »
Trying to figure out how to adjust my ABV from adding fruit. Forgive me if this is a bad idea. The only thing I can think of is to take a gravity reading before and after adding the fruit. Any increase in gravity from the fruit would be added to the OG?

It sounds counterintuitive, but you probably don't need to adjust it at all. Even though you get a second fermentation from fruit, ABV doesn't change much because fruit is mostly water. So the sugar that ferments into alcohol from the fruit gets diluted in turn by the fruit's water. When I make a fruit beer for my wife I don't even count the fruit toward abv.

Ah ok. That makes sense. Good to know I don't really need to worry about it. Thanks!
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Offline HoosierBrew

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Re: sugar contribution for fruit in secondary
« Reply #3 on: March 25, 2014, 05:19:09 PM »
Trying to figure out how to adjust my ABV from adding fruit. Forgive me if this is a bad idea. The only thing I can think of is to take a gravity reading before and after adding the fruit. Any increase in gravity from the fruit would be added to the OG?

It sounds counterintuitive, but you probably don't need to adjust it at all. Even though you get a second fermentation from fruit, ABV doesn't change much because fruit is mostly water. So the sugar that ferments into alcohol from the fruit gets diluted in turn by the fruit's water. When I make a fruit beer for my wife I don't even count the fruit toward abv.

Ah ok. That makes sense. Good to know I don't really need to worry about it. Thanks!

Took me a while to get my head around it at first. Seems like it should bump your abv a decent amount, until you think about all the water.
Jon H.

Offline tschmidlin

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Re: sugar contribution for fruit in secondary
« Reply #4 on: March 25, 2014, 11:10:54 PM »
If you really care you can google for sugar content of various fruits.
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Re: sugar contribution for fruit in secondary
« Reply #5 on: March 26, 2014, 08:55:49 AM »
We have a chart of that (and veggies!) in the upcoming book.
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Offline trickydick

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Re: sugar contribution for fruit in secondary
« Reply #6 on: May 07, 2014, 07:18:14 AM »
Knowing the sugar content of the fruit doesn't seem to easily translate into an answer to the question.  You can look and get a range of Brix values for fruit, but I don't understand how that knowledge is going to let you know how the addition will change the resultant ABV of the beer. I'm trying to plan one myself, but don't want to knock the ABV out of the park by adding a big fruit addition into the secondary as a purée.  Are there any rules of thumb to follow?  If you used an equivalent amount of sugar, there would be a whopping effect on the ABV, but this wouldn't take into account the volume of water being introduced from the fruit.  I'm thinking about just brewing it dialed back 5-10 points on the OG from the mash and see what happens, having almost given up on trying to find a way to accurately calculate.

TD

Oh, what's the book you're doing Denny? 

Edit- after further investigation, it seems that there is a way that you can determine the pppg of fruit if you know its Brix, which you can measure, or google.  Sure would be nice to have a table for common fruits for estimating.  I think blueberries it's 5pppg. I think also can use brewing software to change the yield of a grain into the measured Or estimated Brix of your fruit, and use this modified grain ingredient as a surrogate for your fruit. 
« Last Edit: May 07, 2014, 08:05:43 AM by trickydick »

Offline Jimmy K

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Re: sugar contribution for fruit in secondary
« Reply #7 on: May 07, 2014, 08:12:34 AM »
If you know the brix of your fruit, you can convert that to a specific gravity value (Google brix specific gravity calculator). Then calculate the new OG of your wort by:
 
([Fruit SG] * [Fruit Volume]) + ([Beer OG] * [Beer Volume])
    -------------------------------------------------------------            = OG of Fruit Beer
                                [Total Volume]
 
For an expected FG, use the original beer's expected FG as the sugars in most fruit are completely fermentable.

Also, if you convert fruit brix to SG you can guestimate the impact on ABV. If the SG is higher than your beer's OG, ABV will increase. If it's lower then ABV will actually decrease.
« Last Edit: May 07, 2014, 08:15:06 AM by mtnrockhopper »
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Offline goschman

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Re: sugar contribution for fruit in secondary
« Reply #8 on: May 07, 2014, 08:37:10 AM »
Thanks! I had basically decided to not worry about but did the calculation out of curiousity.

One pureed pineapple (6 cups) increases my OG by 0.0033. Not worth the bother in this circumstance.

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Offline trickydick

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Re: sugar contribution for fruit in secondary
« Reply #9 on: May 07, 2014, 08:44:35 AM »
If you know the brix of your fruit, you can convert that to a specific gravity value (Google brix specific gravity calculator). Then calculate the new OG of your wort by:
 
([Fruit SG] * [Fruit Volume]) + ([Beer OG] * [Beer Volume])
    -------------------------------------------------------------            = OG of Fruit Beer
                                [Total Volume]
 
For an expected FG, use the original beer's expected FG as the sugars in most fruit are completely fermentable.

Also, if you convert fruit brix to SG you can guestimate the impact on ABV. If the SG is higher than your beer's OG, ABV will increase. If it's lower then ABV will actually decrease.

Thanks.  I think this is what I need to get a more precise answer to my problem.    I am planning to add about 2.5-3 pounds per gallon of blueberries which I will purée and add to secondary.  I have found that they have a brix of about 10-11% but can be higher or lower.  I will not know the volume until I have puréed them, and I will also try measuring the brix with my refractometer. 

 I'm wondering how does one calculate the pppg of a fruit based upon the brix.  I think pppg means how many points per pound per gallon. For my plan of adding 2.5 pounds per gallon, having this number would be helpful.  I think I stumbled upon 5 pppg somewhere for blueberries with a 10.2% sugar content  which I think is synonymous with Brix.  I'm not sure how to get the 5 pppg from the 10.2% though (divide by two?). Would be nice to know how to do this. 


Thanks!

TD

As I reflect upon this more, it seems that the pppg approach is not going to be very accurate because it neglects to account for the volume of the fruit.  I have also read a rant at themadfermentationinst.com which brings a sense of practicality to the math, and upon further reflection, it seems that my target OG is 1.049, that the SG of the blueberries is going to be very close ( one calculator I got 1.0442 assuming 11% sugar ). Therefore, it might be simpler to ignore the effect of the fruit.  I'm happy that I at least looked into what effect the 12.5 pounds of fruit I was adding would do because I would've been upset if I was shooting for a 5.8% beer and ended up with 8 or 9 percent beer.
« Last Edit: May 07, 2014, 09:06:55 AM by trickydick »