Energy in Foods Experiment


Living beings require a certain amount of food energy to sustain their metabolism in order to perform their daily tasks. The food that people eat constitutes this required energy and is stored in the chemical bonds. Generally, there exist various types of energy giving foods whose energy potential is influenced by the type of food. In some cases, some energy that is in these foods is not utilized is the daily tasks performed by people. The energy content that is in the chemical bonds of food can be subjected to measurement through the use of the specified process of exposing it to heat in a controlled environment. Ideally, it is said that for a commonly active individual, the total amount of energy that one can use on an average day is 2000 kcal. In simple terms, this is close to 8360kJ of energy.

Scientific background

The total energy in food is composed primarily of carbohydrates, fats, proteins, and water. These contribute to the majority of food energy constituents with a specified margin of 90%. In addition, other notable constituents are vitamins and minerals. These food constituents are formed through a process called photosynthesis where plants use sunlight to convert the carbon dioxide and water into the atmosphere to subsequently form glucose and oxygen. Naturally, the glucose (sugars) that results from the process is in chemical bonds. It is consumed by breaking the chemical bonds in a process known as cellular respiration. This process generally involves metabolic reactions of breaking down of the food nutrients into usable energy.

There exists a harmonized system of measuring food energy. The International System of Units use joules and its multiples kilojoule as a measure of food energy. Food energy is measured through the use of specified units known as calories. A calorie is defined as the quantity of heat needed to raise one gram of water by one degree Celsius. One kcal comprises of one thousand calories. The following formula is used to calculate the energy content of food samples.

Total Energy = Volume of water x (initial temperature -final temperature) x


To determine and analyze the energy value of different foods by exposing a sample of each variety to heat through the use of use of a computer-controlled mechanism.


The calorific values of the three samples were successfully calculated. Isaac, Owen, and Sally had the energy values of their samples at 7.06, 9.53 and 9.80kcal respectively. On average, an energy value of 8.80kcal/g was arrived at. However, the average energy value of the walnuts used in the sample slightly differed from the Literature value: 100 g walnuts contain 653 kcal of energy, or 6.53 kcal/g. This was attributed to the presence of some errors in carrying out the experiment and due to the heat lost to the surrounding during the process. The errors would result from recording incorrect data from the masses of the samples and other readings used in the experiment. Further errors would result in the calculation of the energy values.

The random errors included the inconsistency in mounting the food samples at identical configurations in the entire experiment and the use of unidentical water volumes which may cause the food sample to heat a larger mass of water than the corresponding samples. Systematic errors would include the use of faulty equipment like the temperature measuring device and the use of contaminating materials in the experiment. Improvements in the experiment would include the burning of more samples to reduce the occurrence of errors and increase the accuracy of the results. For instance, the initial temperatures of the original samples and its mass could be put under special considerations.


  1. Sally’s walnut with a value of 9.80 kcal/g
  2. Again, Sally’s sample of walnuts appears to have a high energy source. It has a corresponding constituent of protein, fat and carbohydrates at 15, 65 and 14 percents respectively which have high energy levels.
  3. The known literature value of energy per 100 g walnuts contains 653 kcal of energy, or 6.53 kcal/g. This energy majorly originates from the fats and protein present in the nuts. For instance, Walnut comprise of 65% fat, protein at 15% among others.
  4. Every food constituent contains a certain threshold of calorific value. Some food constituents like carbohydrates have a high energy capacity than other constituents.
  5. Because the energy value from the in dietary books are standards that have been done using the same process. I would not expect my results to deviate a lot from these values.
  6. Here are some other energy values for other food constituents.
Food constituent Energy value in kilojoules per one gram Energy value in kilocalories per one gram
Fat 37.00 9.00
Alcohol 29.00 7.00
Proteins 17.00 4.00
Carbohydrates 17.00 4.00
Organic acids 13.00 3.00
Polyols 10.00 2.40
Fiber 8.00 2.00