Science Fair Project [If its not appropiate, remove it]

Hello!
Guys, I need sum help for my science fair project.
As many of you guys know, I'm from 8th grade, so I have science fair. Its gonna be in 12 days

I am doing an experiment on fruits, and how much electricity each fruit produces. I am testing:
-Mango
-Lemon
-Cherry
-Apple
-Peach
-Tomato (its technically a fruit)
-Pummelo

If you guys know a lot about this course, could you tell me what are the stuff that affect the electric output from fruits??

So far, my hypothesis is that amount of Zinc, pH, and amount of sugar affect electric output.

Tell me if you know more!!

[termi, or other mods. You can take this post away if its in the wrong section or can't fit in webmaster talk]

Unfortunately I don't know too much about this subject, maybe you will find someone who can help you.

Regards,
Ovi

Hi,
I need you to clarify your statement, are you testing the conductivity of this friuts if so in what form, or like you said testing for their ability to generate electricity?
If so you will need to shed more light on it. I know that all living things generate a form of electricity but this is a tough one for the 8th grade. But then you are a whizzkid aren't you?
I am interested in your finding although I'm not sure this is the right forum though.
However let me wish you good luck.