I.S. How to know the energy that the food contain?

Prepare a burning spoon, 3 kinds of food,Busen burner,beaker,50ml water, thermometer
measure the mass of the 3 food
Put the food on the burning spoon
Put the thermometer in the breaker filled with 50ml water
Burn the food until it has a flame, put it under the breaker
Repeat it with other 2 food

Results:
Temperature rise/mass
The food which has the most temperature rise of water per gram has the most energy