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The science of nutrition and healthy eating
The science of nutrition and healthy eating

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2.3 Protein in foods

In the next activity you can test your knowledge about protein.

Activity 2 Protein content

Timing: Allow approximately 10 minutes.

When you go to the activity, you will see eight foods that contain protein. Can you work out which has the most protein?

Arrange the foods in order from that containing the most protein at the top, to the least protein at the bottom. To move a food option, click on it and drag it to a new position. There is no limit to the number of moves you can make. As soon as you move the boxes into the correct order, a message will appear.

After eight moves, you will be asked whether you want some assistance. This will add green ticks next to those that are in the correct position and red crosses next to those that are not.

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The correct order is as follows:

  1. chicken breast
  2. grilled lean beef steak
  3. cheddar cheese
  4. grilled salmon
  5. almonds
  6. egg (hen’s)
  7. bread
  8. kidney beans

You may be surprised to find that eggs, which are often considered to be a good source of protein come a long way down the list.

An egg contains only 12% protein compared with over 30% in chicken and steak. That is because they eggs contain a lot more water than meat, which is also why the inside of a raw egg is quite runny. When an egg is hard-boiled, although it appears dry, it has not lost any of the water. In the uncooked egg, the microscopic protein molecules (made up of chains of amino acids) are curled up into neat balls. The water molecules lie between them, allowing them to roll over one another, so that the egg is runny.

When the egg is cooked, the heat causes the neat little balls to unravel and the protein molecules then form bridges across from one to another, similar to the ones shown between the two chains of insulin in Protein sequencing. This makes the egg solid. The water molecules are still present, but trapped in the network of protein molecules.