Canned vs Frozen Vegetables

Approximate Cost

$10

Safety Issues

This project requires the adult supervision.

Material Availability

All materials for this project can be obtained from the grocery store.

Approximate Time Required to Complete the Project

1-2 Weeks

Objective

To determine if frozen vegetables have more nutrients than canned vegetables.

The project goals include estimating the number of calories stored in equal masses of frozen and canned vegetables as a means to measure the amount of stored energy the food sources contain.

Materials and Equipment / Ingredients

• Canned peas and canned corn
• Frozen peas and frozen corn
• Matches
• Triple beam balance
• Two tin coffee containers
• Thermometer
• Metal Rod
• Water bath
• Food Source
• Cork

Calorimeter Diagram

Introduction

Upon consumption, food sources are broken down by enzymes within the mitochondrial matrix of cells yielding energy storing molecules that readily release energy to perform cellular and bodily functions. The amount of energy required to raise the temperature of 1 kilogram of water by 1 degree Celsius is equivalent to 1 Calorie of energy. Using a calorimeter, food scientists can estimate the amount of energy or number of calories a food source stores. The calorimeter is setup in such a way that a known quantity of food is burned releasing its stored energy in the form of heat. The heat transfers to raise the temperature of a known volume of water. The increase in water temperature multiplied by the mass of water in the calorimeter is equivalent to the amount of energy absorbed in the calorimeter from the oxidation of the food source. The equation for the energy transfer is provided below:

Q = mc(T_final – T_initial)

C is the heat capacity of the water, 1 calorie per gram per degree Celsius.

T_final is the final temperature of the water following combustion of the food.

T_initial is the initial temperature of the water before combustion of the food.

Research Questions

• How are nutrients stored?
• How is the energy stored in food transformed?
• How are calories measured in food sources?
• What techniques do food scientists use to measure the amount of energy stored in food?
• What is a calorimeter?

Terms, Concepts and Questions to Start Background Research

• Calorie
• Calorimeter
• Combustion
• Kilojoules
• Oxidation
• Specific heat capacity
• Thermodynamics

Experimental Procedure

1. Using a can opener, remove the bottom of a large tin and remove the lid.
2. Drill several holes in the base of the large tin.
3. In a smaller tin that can fit inside the larger tin, drill two holes on either side of the container to allow for a metal rod to pass through the holes and rest the small tin inside the larger tin.
4. Place the apparatus over a cork with a linear wire sticking into the cork. The wire and cork will support the suspension and burning of the food substance beneath the suspended smaller tin can inside the larger tin can.
5. Select a frozen pea and a canned pea of identical masses to begin the experiment. Use a triple beam balance to measure the mass of the peas.
6. Stick the wire of the cork into the frozen pea and suspend the pea under the tin can inside the calorimeter.
7. Fill the smaller tin can with a known volume of water. This quantity is a measure of the mass of water in the calorimeter.
8. Record the temperature of the water. This quantity is a measure of the initial temperature, T_initial.
9. Using the matches, light the frozen pea and allow the pea to burn to completion inside the calorimeter underneath the suspended water container.
10. Stir the water inside the small container and record the temperature of the water. This quantity is a measure of the final temperature, T_final.
11. Carefully remove the burned frozen pea when it has cooled and measure the mass of the frozen pea using a triple beam balance.
12. Repeat steps 5-11 for the canned pea and other food sources for comparison, for example frozen and canned corn.
13. Substitute the values of the average final and initial temperatures, masses of water and food into the equation for energy transfer and solve to find the value of Q for each food source, a measure of the heat capture in calories.

Bibliography

Food Preservation Techniques by P Zeuthen © 2009 Woodhead Publishing Limited