Why does the colour leak out of cooked beetroot?

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Why does the colour leak out of cooked beetroot?

Hypothesis:

Increasing the temperature of water baths surrounding sections of beetroot will cause the partially permeable membrane of the vacuole to become less stable, causing it to lose control of transport across, and allow betalains, red pigments, to pass out of the tonoplast and cause the beetroot to lose colour. When the distilled water containing the beetroot is tested, it will absorb much more light because the pigment leaked into it will cause it to become opaque. As we increase the temperature, so will the amount of pigments released increase, in a directly proportionate positive correlation.

Aim:

To find out if increasing the temperature of beetroot samples will affect the containment of pigment.

Method:

  1. We placed 8 slices of previously prepared 1cm³ beetroot into boiling tubes containing 5cm³ distilled water.
  2. These we placed into water baths at temperatures of 0°C, 10°C, 20°C, 30°C, 40°C, 50°C and 6O°C, leaving them for thirty minutes to ensure that the beetroot and water reached the required temperature. For the water baths we used a selection of ice, salt, and boiling water to reach the desired temperature.
  3. We then removed the beetroot sections from the boiling tubes, and shook the water and pigment solution to disperse the dye, and break any ice where appropriate.
  4. From each boiling tube we took a sample of the solution and placed it into a cuvette. We used a calorimeter to find out how much light was absorbed when passing through each sample. This was to show us

Variables:

  • One factor that must be controlled would be the temperature of the water baths – it must be ensured that they remain at the same temperature through the entire half hour the beetroot are in them, or the rate at which the pigment leaves the vacuoles will not be steady.
  • We must also ensure that we make no mistakes using the calorimeter, and that we check that each sample is comparing against colourless distilled water, not another of our samples.
  • We must make sure that each piece of beetroot used is of a very similar, if not identical, size.
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Safety:

Because we did not prepare the beetroot samples ourselves, there are no specific safety measures to follow except for general laboratory guidelines such as wearing a lab coat and perhaps safety goggles.

Results: Table to show the absorbance of light from mixtures of distilled water and beetroot pigment solutions

Analysis:

  We did this experiment to determine how increasing the temperature of the cell would affect the amount of pigment leaked into the surrounding water, and therefore how much light would be absorbed when tested with a ...

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