To determine the amount of energy in different foods and to find out how much this depends on the fat content of the food.
Biology Coursework Jaspreet Athwal 10P/10D2
Burning Foods Investigation
Aim: To determine the amount of energy in different foods and to find out how much this depends on the fat content of the food.
Most foods contain fats, carbohydrates and proteins, usually in a mixture. These are all organic molecules, which contain energy. This investigation looks at the amount of energy in six different foods. Energy values are measured by burning the foods underneath a boiling tube containing a fixed volume of water. The temperature rise in the water can be used to calculate the energy values in the water.
Energy released from food (J) =mass of water (G) x temperature rise (°C) x 4.2
If you divide this value by the mass of the food, you get a fair comparison.
- Test tubes
- Mounting needle
- Retort stand with clamp
- Bunsen burner
- Gather equipment, test tubes, Bunsen burner, foods and retort stand.
- Pour exactly 15cm³ of room temperature water into the test tube.
- Clamp the test tube using the retort stand and place thermometer inside.
- Record the temperature of water.
- Find the mass of the food and record.
- Place the food onto a mounted needle.
- Place over the Bunsen burner until it catches fire.
- Place directly under test tube until it cannot set alight anymore.
- Take the temperature of water and record.
- Calculate the energy (see above).
- Repeat with other foods.
[To compare results, energy per gram needs to be calculated.
This is a preview of the whole essay
Energy released from food (in J/ G) =energy in the food (from
Formula above) weight (g)]
The independent variable is the rise in temperature of the water. I will take the temperature before the experiment. I will then take the temperature after the experiment.
Goggles must be worn to protect the eyes from spitting of food when alight and incase test tube breaks due to the heat from the Bunsen burner.
You should be standing whilst performing the experiment just incase the Bunsen burner should drop.
How will the experiment be a fair test?
I will make the experiment a fair test by using the same amount of water in the boiling tube. This water will also be from the same tap. I will also make sure that the food is burning at the same distance from the boiling tube. These are the constant variables.
- Proteins and carbohydrates have more oxygen atoms and less carbon and hydrogen atoms. However, fats have less oxygen but a lot of hydrogen and carbon. These burn unlike oxygen, which does not burn therefore, more energy is released.
- There are several theories to describe the absorption of fats. The main view shared is that fats are absorbed by the epithelial cells of the lining of the small intestine.
- When we eat food, carbohydrates are the first ones to change into energy. Our bodies only use a small amount of fat for energy. 40% of the total calories we consume come from fat.
- There are two kinds of fat, saturated and unsaturated. Saturated fats are commonly found solid at room temperature. Unsaturated fats are liquid at room temperature.
- Fats that we eat enter the digestive system and meet with the enzyme, lipase. Lipase breaks the fat into its parts: glycerol and fatty acids. These are then reassembled into triglycerides for transport in the bloodstream. Muscle cells and fat (adipose) cells absorb the triglycerides either to store them or to burn them as fuel.
- One gram of fat contains 9 calories of energy. When burnt, the calories would be released due to the flames.
- We acquire energy to preserve metabolism and during any physical activities in our everyday lives.
- Carbohydrates contribute to 44% of our total energy whilst fats contribute to about 41%.
- Fats - Also known as lipids, fats produce twice the amount of energy that carbohydrates are capable of producing, and this is due to the more complex nature of their structure. Their are five different types of lipid, either, triglycerides, phospholipids, glycolipids, steroids and waxes
- Fats help stabilize blood sugar
- Fats cushion vital organs and help to maintain body temperature.
- Fats delay hunger pains due to a mixture, which contains fat that remains longer in your stomach.
- Saturated fats can raise level of cholesterol in blood.
- Fats tend to burn slowly.
- Unsaturated fats tend to burn much more quickly, therefore releasing energy more efficiently.
- Fats are made up of 3 fatty acids joined together.
I predict that the pumpkin seeds will have the most energy as they contain the most fat. I based this prediction on the fact that the more fat content food has the more it should burn. I also predict that the dried peas will have the least energy as they contain the least fat.
The table clearly shows that Sunflower Seeds contain the most energy. The test did not prove my theory. The crisps had the least amount of fat, which again did not prove my theory. This may have been because there was more oxygen in crisps than the other foods.
The results were not as I predicted. The sunflower seeds turned out to contain the most energy. I was surprise to find out this as I based my theory on the fat content but the experiment shows that fat content does not provide the most energy. The pumpkin seeds may have contained less carbohydrates than the sunflower seeds, which resulted in less energy.
Looking at how I performed the test I could have changed a few variables. Firstly, I could have carried out the experiment in a separate room to other students as the room temperature kept rising due to the constant heat from Bunsen burners.
I could have used a clamp to hold the mounted needle, instead of my hands that were not always steady, to be sure that the food was the same distance from the test tube.
To ensure the experiment was a fair test, some of the different foods could have been dried out to make sure all the water content had been removed; therefore, more flames would have been produced from energy within.
I do not think I could have done anything to affect the water temperature as it was taken straight from the tap. I could have used the same syringe to pour the water to make the measurements the same as the syringes used may have had a slight difference in measurement.
A better result could have been achieved by performing the experiment in a different room as many students were performing the experiment at the same time.
Using a digital thermometer instead of a standard thermometer would have enabled me with a more accurate reading, therefore providing me with a more accurate energy content.
The amount of water could have been increased to obtain better results. Instead of only using 15cm³ of water this could have been increased to 30cm³of water.