Why do some fruits and vegetables conduct electricity?
"Fruits and vegetables conduct electricity in the same way a salt solution will complete an electrical circuit," associate professor of Materials Science and Engineering, Michael Hickner, told Live Science. "It's due to the ions in the salt solution. They don't conduct electrons [as traditional electrical conductors do].”
An ionic conductor contains positive and negative charges (‘charged ions’) that move freely when they come into contact with a voltage. For example, when table salt is dissolved in water, the sodium and chloride (which have opposite charges, as Na+ and Cl-) create an ionic solution. These ionic solutions are called electrolytes and can be found in every living thing. Because of this, technically, any fruit or vegetable could become an ionic conductor, but some are better at it than others. This is also why salt water or unfiltered tap water are better ionic conductors than filtered fresh water.
The best food battery is any fruit or vegetable that has high levels of superconductive ions, such as potassium or sodium, and the proper internal structure to create a working current. Potatoes, which have homogenous structures, and pickles, which have high levels of sodium and acidity, are good examples of such foods. For an extra electrical "oomph," you can soak your potato in salt water before setting up the potato battery experiment.
In contrast, tomatoes have unorganized, messy insides and often leak, and even an orange -which has high levels of potassium- won't work well, because the fruit is divided into internal compartments, and these create barriers that block the current.
