Why does colour leak out of cooked beetroot?
When cooking a beetroot you are recommended not to remove the outer skin and not to cut off the entire stalk if you do not want the red dye in the cooking water. Beetroot contains a red pigment called betalain, which is in the cell vacuole. Normally the betalain stays inside the cell, however when the cell is exposed to extreme temperatures they leak out. The reason why they leak out is because of the cell membrane structure. When the cell membrane is exposed to extreme heat the proteins unravel and the lipids melt. This will allow the betalain to leak out from the cell vacuole. Under extreme cold the cell membrane will freeze and fracture also allowing the betalain to leak out into the extracellular. The Betalains function is really unknown, but it has been suggested that when present in flowers it is used to attract insects for pollination and when present in seeds attracts birds for dispersion. There is no indication that betalains protect plants from pathogens or herbivores, and they also do not absorb UV light. Betalains are also poor pH indicators. In this experiment the betalain will be measured by using a colorimeter. A colorimeter is an instrument which compares the amount of light getting through a solution (Betalain) with the amount which can get through a sample of which is clear (distilled water). A reading is then given of which shows the percentage of absorbance. This gives the results for the experiment. The independent variable for this experiment is the changing of the temperatures The dependent variable would be the colouration in the water because of the temperatures.
Under intense heat the proteins will unravel and the lipids will melt under intense cold the membrane will freeze and fracture, therefore Betalain (stain) will leave the cell
There will be no significant difference in the amount of betalain lost from the cell, regardless of the...
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