Fruit Addition to Secondary and OG

[NelsonNelson]

Hi all,

I recently was eating some mangos and my tastebuds were overwelmed with citrus and evergreens, reminding me of my favorite IPAs. Playing somewhat off Dogfish's Aprihop, I am in the process of making a Mango IPA(In primary). I've read some threads on fruit additions to the secondary and I'm comfortable with both arguments of either pasteurizing, or letting the alcohol take care of the nasties. My concern is if/how the fruit is going to change my OG.

Does anyone have any words of wisdom on the relationship with the amount of fruit added and the effects it has on OG?

Thanks

 

[Chipman]

I've been thinking about the same thing actually. Brewed up a pale ale and racked it onto a few pounds of blackberries with no clue how much more sugar that's going to add. I can maybe see a couple ways to figure it out though.

1. Take a known amount of the fruit and a known amount of water, let it soak up some goodness from the fruit and take a gravity reading of that. X points of gravity in Y volume of liquid should translate to Z points of gravity in... W volume of water.

2. Add the fruit to the 2ndary, let it sit for several hours to get all soaked in, then take a reading before the yeasties start having at it again. Or even after they do and you'll still get a good idea for the new grav.

3. Do what I did which is nothing and hope for the best! and that the fruit covers up how alcohol it REALLY is ehehehe.

 

[bovineblitz]

I don't really have any advice on the new gravity level, but how do you prep mango?

 

[dcp27]

I can't remember which thread it was in, but I saw this link before that gives the sugar content of various fruits, which can be used to figure out how much it adds to your beer: http://hbd.org/brewery/library/SugAcid.html

 

[NelsonNelson]

Whelp, I just racked into the secondary on top of 4-5 lbs of unpasteurized mangos (unpasteurized, however everything that came in contact with the fruit was thoroughly sanitized). For now, I did as Chipman did, which was nothing as far as measuring and countermeasuring for my new OG. Just shooting from the hip and hoping for the best.

Sometime in the near future, I plan to perform a few science experiments similar to Chipman's suggestion #1,

1. Take a known amount of the fruit and a known amount of water, let it soak up some goodness from the fruit and take a gravity reading of that. X points of gravity in Y volume of liquid should translate to Z points of gravity in... W volume of water.

I hope to take those results along side the data from http://hbd.org/brewery/library/SugAcid.html and maybe figure out the rest of this equation.

Thanks for advice and the link, guys. I'll post back to this thread after my experiments to let you know if I've come up with any theories.

 

[Shepherd5]

I thought of doing this at some point with mangos. I especially like the taste that the skin of the mango has, thought it might be an excellent combination in a summer IPA

 

[dcp27]

I'm not positive, but my guess is that since mango's are about 11% sugar (according to the link), and you added 4-5lbs of them, that it's about equivalent to 0.5lb of sugar or about an additional 0.004 SG to a 5gallon batch.

 

[Hex]

Is the wort sweeter than the fruit?

If that is the case, your ABV will drop when you add fruit to beer because you are adding a greater amount of water than sugar to the end product.

(at least that is how I see it from my limited experience with fruit beer and wine)

 

[NelsonNelson]

Thanks to Google and the University of Georgia's College of Agriculture and Environmental Sciences, I found this neat bio/chem experiment

http://apps.caes.uga.edu/sbof/main/lessonPlan/fruitFermentation.pdf

This is more or less the type of experiment I am going to try.

 

[FirefighterSR2]

Is the wort sweeter than the fruit?

If that is the case, your ABV will drop when you add fruit to beer because you are adding a greater amount of water than sugar to the end product.

(at least that is how I see it from my limited experience with fruit beer and wine)

Most fruit runs 4-6% sugar. So, a pound of blackberries would add about an ounce of sugar while diluting the batch around 5%.

Net loss in SG.

I stole david_42's quote from another thread, but it would seem to support the idea of a net SG loss from the fruit addition.