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Old 12-30-2009, 11:32 PM   #1
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Default Fruit Beer and Alcohol Content?

Is there a method to determine the alcohol content of a Raspberry Wheat when adding the fruit to the secondary. Fermentation seemed to get pretty active again when I put the beer on top of the fruit in the secondary.

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Old 12-30-2009, 11:36 PM   #2
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right because the yeast where eating the fructose. when you added the fruit you diluted the beer lowing its ABV. when the yeast ate the fructose they created more alcohol raising its ABV. take a gravity reading as normal.

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Old 12-31-2009, 05:39 PM   #3
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I think the point is that the ABV is based on the difference btwn the high gravity reading and low gravity reading. But since he doesn't truly know the high b/c of the extra sugar from the fruit his OG isn't accurate.
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Old 01-02-2010, 03:32 PM   #4
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This is just my stab at it. I posted it in the beginner forum thinking that this question had to have been a newbie question, no one replied.

Ok I searched for a bit for a ABV formula for times when something is added in the secondary and came up empty. Maybe I'm searching using the wrong words, anyway please help. Here is my best guess at it. Please help check my logic

OG = Original Gravity
PG = Primary Gravity (After initial fermentation before adding fruit)
SG = Secondary Gravity (After adding fruit)
FG = Final Gravity
PV = Primary Volume (Before adding fruit)
SV = Secondary Volume (After adding fruit)

Step 1
(OG-PG) * 131 = 1ABV
This will figure out the ABV for the original brew. When we add the fruit it will dilute the ABV so the way I figure we will need to create a ratio to multiply the 1ABV by before adding it to the 2ABV.

Step 2
PV/SV = 1ABVweight
Using this weight will determine dilution of the ABV

Step 3
(SG - FG) * 131 = 2ABV
This will figure the alcohol increase between the addition of fruit until the fermentation is complete or stopped.

Step 4
(1ABV * 1ABVweight)+2ABV
Unless I am missing something (definite possibility) this is the calculated final ABV
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