Calculating the effect on OG of adding fruit

I have nearly a gallon of seedless Raspberry puree, and while I could pop a hydrometer into it, it is so viscous that I am not sure that this method would give me a reasonably accurate reading. It has the viscosity of a milkshake.
It occurred to me as I write this though, that a refractometer would not have this issue. But I have not acquire such an advanced piece of equipment.
As it is, how about cutting the puree with equal volume of water to get a more watery solution, hoping for a better "float" then doing the math on the dilution.
(maybe I just answered my own question)
Anyone else faced this or cared enough to deal with it to this level ?

I am not as retentitive as I sound, I just love the math part of this hobby as well and hate to not know.

Thanks.

Indiana Red said:

I am not as retentitive as I sound, I just love the math part of this hobby as well and hate to not know.

Click to expand...

Hey, me too man.

Yeah, cut it with some distilled water. Measure the amount of extract and water by mass (call them m_e and m_w resp.). Measure the gravity of this solution and convert it to Plato (call it P). Now, solve the equation x*m_e/(m_e+m_w) = P/100 for the yield of the extract x. Now you can use this yield like any other grain yield in your OG calcs.

Ever work out the PPG for the fruit?

I was just trying to figure out the fruit contribution to a blackberry ale I made a couple months ago. I racked on top of 5lb of fresh picked (briefly boiled) fruit in the primary. OG was 1.051, but that didn't include a good mixture with the fruit.