Levels of carbohydrates in different varieties of milk
The materials required for this science fair project:
- 100 ml of low fat milk
- 13g of non-fat powdered milk
- 100ml of soy milk
- 3 beakers
- 1 hot plate
- 1 thermometer
- 1 bottle 10% acetic acid
- 1 stirring rod
- 12 grams of calcium carbonate
- 6 pieces of filter paper
- 300ml of ethanol
- 3 Erlenmeyer flask
- 1 digital weighing scale
1. For this science fair project, the independent variable is the type of milk used. The dependent variable is the amount of lactose crystals formed, which will be determined by weighing the crystals with a digital weighing scale. The constants (control variables) are the temperature of the environment (which will remain at room temperature), the amount of milk used and the process of extracting the lactose.
2. Label the 3 beakers as milk, powder milk and soy milk. Label the 3 Erlenmeyer flasks in the same way.
3. Pour the low fat milk and soy milk into their respective beakers. In the last beaker, mix 13g of powdered milk into 87ml of warm water. Place the 3 beakers on a hot plate, and bring the temperature of the liquids in the beakers to 55°C. Check the temperatures with a thermometer.
4. While stirring the milk in the beakers, add drops of acetic acid till the liquids turn colourless and a mass of casein protein forms in each beaker.
5. Remove the casein and add 4 grams of calcium carbonate to the remaining clear liquid in each beaker. Stir for a few minutes.
6. Increase the temperature of the hot plate to bring the liquid in the beakers to a boil. Stir the liquid in each beaker with a stirring rod. The remaining proteins will precipitate. Filter the solutions into their respective Erlenmeyer flasks and continue heating until only 25ml of solution is left.
7. Add 100ml of ethanol to the 25ml of solution in each Erlenmeyer flask, and allow to cool. Filter the liquids again. Heat the liquids in their Erlenmeyer flasks, then allow to cool slowly.
8. As the solutions cool, lactose crystals will form in each Erlenmeyer flask. Collect these crystals and measure their weights with the digital weighing scale. Record each measurement in a table, as shown below.
Handle hot liquids with care