How much energy is in a single grape?

Question

how many joules of energy can be extracted from a single grape?

Answer 1

There are many ways to extract energy, and since you're too lazy to even specify how, I will give you the laziest answer. E=mc^2. To do this extraction you'd react it with an identical-sized grape made of antimatter.

Ok, to tone down the sarcasm a notch, if you're looking for calories, an average grape is about 85% water and the rest more or less sugar, and sugar has 4 Calories/gram. Figure out the mass of your grape, and you've got a vague calorie count.