Calculating gravity change for fruit additions?

[nhenson22]

Wondering if any smart people out there could point me towards some info on this....

I've added 1kg of frozen mango chunks to my primary about 7 days in. I can see that this has kicked fermentaion off again.
So my question is how do I go about calculating how many gravity points I have added with this addition, and therefore the change to the final ABV of the beer?

Cheers for any help!

 

[Hazelwood Brewery]

Sure. You need to know the amount of sugar in the fruit as one of your variables. If you still have the pack the fruit came in it will tell you how many grams of sugar there is in 100g of fruit. If you don’t have the pack then the published information on sugar content will be the next best thing, this is 11g.

Assuming 11g /100g of fruit you have 110g of sugar in 1Kg of mango. Expressed as kilos you have 0.11 kilos of sugar.

Simple sugars have an extract potential of 46 gravity points per pound per (US) gallon. We tend to work in Kilos and litres so multiply by 8.35 to get points per kilo per litre: 46 x 8.35 = 384

You don’t have a kilo of sugar in your fruit so adjusting this for the weight you do have (above, bold): 0.11 x 384 = 42

So you would have 42 gravity points if you concentrated all that sugar into 1 litre of wort. If you have more than 1 litre of wort, divide 42 by the number of litres in your FV, say 23: 42 / 23 = 1.8 gravity points.

The additional ABV is 0.13125 x gravity points (all the sugar will be converted to alcohol): 0.13125 x 1.8 = 0.24%

 

[nhenson22]

Sure. You need to know the amount of sugar in the fruit as one of your variables. If you still have the pack the fruit came in it will tell you how many grams of sugar there is in 100g of fruit. If you don’t have the pack then the published information on sugar content will be the next best thing, this is 11g.

Assuming 11g /100g of fruit you have 110g of sugar in 1Kg of mango. Expressed as kilos you have 0.11 kilos of sugar.

Simple sugars have an extract potential of 46 gravity points per pound per (US) gallon. We tend to work in Kilos and litres so multiply by 8.35 to get points per kilo per litre: 46 x 8.35 = 384

You don’t have a kilo of sugar in your fruit so adjusting this for the weight you do have (above, bold): 0.11 x 384 = 42

So you would have 42 gravity points if you concentrated all that sugar into 1 litre of wort. If you have more than 1 litre of wort, divide 42 by the number of litres in your FV, say 23: 42 / 23 = 1.8 gravity points.

The additional ABV is 0.13125 x gravity points (all the sugar will be converted to alcohol): 0.13125 x 1.8 = 0.24%

Thanks, very detailed explanation. I do still have the packaging, 13.3g per 100g, so I have calculated (in 20L) this should be worth an additional 2.55 gravity points.

Will need to save this somewhere so I don't foget! Very helpful!