Effect Of Temperature On Beetroot
WHY DOES THE COLOUR LEAK OUT OF COOKED BEETROOT?
PLAN
Hypothesis
Temperature has an effect on the leaking of the colour from beetroot. This means that as the temperature is altered there will be a change in the rate of colour leakage.
Scientific Background
Beetroot is a very familiar vegetable and is commonly known as beet. It is famous in most recipe books that advice that its outer skin is not to be removed to avoid getting red dye in the cooking water.
If we look at the internal structure of beetroot, it will be observed that it consists of cells which are surrounded by a cell membrane. This cell membrane structure separates the contents of the cell from outside. The membrane has tiny holes in it which allows small molecules to pass …show more content…
through but not larger ones. This is known as semi-permeability. Beetroot contains red pigments called betalains in the cell vacuole and normally do not pass through the membrane. However when cooked, the dye leaks out and so I am investigating the effect of different temperatures on the amount of dye and the extent of damage on the beetroot membrane structure which causes the holes to allow larger molecules through. For molecules to move as a whole, they require a certain amount of energy. This energy may be supplied in the form of heat. Heat energy can be measured as temperature which is the degree of hotness or coldness of a body. It can be predicted that as temperature increases, the reading of the colorimeter will increase since betalain molecules will acquire enough energy to move through the membrane by active transport. There is also the possibility of temperature affecting pore size. As temperature increases, pore size increases.
The colorimeter reading will implicate how much of the betalain has moved out through the membrane since that amount is directly proportional to colour given out.
Procedure
Cut Sections from a single beetroot using a size 4 cork borer. Cut eight, 1cm length slices from these sections. Be careful not to spill beetroot juice on skin or clothing as it will stain very badly.
Place the slices in a beaker of distilled water. Leave overnight to wash away excess dye.
Next day place eight labelled boiling tubes each containing 5 cm distilled water into water baths at 0 C, 10 C, 20 C, 30 C, 40 C, 50 C, 60 C and 70 C. Leave for 5 minutes until the water reaches the required temperature. Place one of the beetroot sections into each of the boiling tubes. Leave for 30 minutes in the water baths.
Decant the liquid into a second boiling tube or remove beetroot sections using a technique that does not squeeze the slice e.g. spear with a pointed seeker. Shaker the water/solution to disperse the dye.
Switch on the colorimeter and set it to read % absorbance.
Set the filter dial to the blue/green filter.
Using a pipette accurately, measure 2 cm distilled water into a cuvette. Place the cuvette into the colorimeter, making sure that the light is shining through the smooth sides.
Adjust the colorimeter to read 0 absorbance for clear water. Do not alter the setting again during the experiment.
Place 2 cm of the dye solution into the colorimeter cuvette and take the reading for the absorbency. Repeat the readings for all the temperatures.
Present results in an appropriate way.
Identify any trends or patterns in your results.
The variables kept constant
The same diameter corer is used so to keep the surface area of each beetroot piece the same size.
The dependant variable was temperature since it was altered in each experiment.
When the beetroot has been cut some of the cell membranes is broken, which means some anthocyanin will leak out. This must be completely washed off in order to maintain the reliability of the results.
I will use distilled water to so that I have a reliable substance to test with a colorimeter.
Excess dye was washed out overnight to ensure more accurate and fair results.
Measurements
Reading of colorimeter was set as that of the empty cuvette to remove the possibility of percentage error.
Accuracy
Water in test tubes will be heated for 5 minutes to obtain the required temperature before beetroot is added.
All beetroot will be cut into the exact same size with a knife to ensure a fair test
Water bath will be lagged to reduce amount of heat being lost to the environment.
Cuvette will be placed into colorimeter with transparent side facing the internal light.
Cuvette will be filled to the top mark by liquid obtained from beetroot.
Each temperature experiment is conducted with 3 test tubes to find the average to ensure accurate results.
Risk assessment
Care will be taken whiles using cork borer and water bath at temperature of 70 C.
REPORT
Change in Procedure
Slices were left overnight the day before to wash away excess dye since time to conduct experiment was limited.
Temperatures 10 C and 30 C were not used in the experiment to save time.
Knife was used instead of cork borer since it wasn’t available at the time.
Discussion
As temperature increased, the reading on the colorimeter increased.
Lowest reading was recorded at temperature of 0 C.
Highest reading on colorimeter was recorded at temperature of 70 C
Amount of pigment released increased with an increase in temperature.
5. There was a gradual increase from temperatures 0 – 40 C, with a significant jump to 50 C.
Explanation of results
The reason why the amount of betalain pigment released (colorimeter reading) from the vacuole increased directly proportionally to the temperature of the water bath (from 20 C to 40 C) is because the amount of random movement of betalain molecules out through the cell membrane depends on the amount of heat energy the betalain molecules are given to convert into kinetic energy- hence the higher the temperature the more betalain lost from the vacuole.
This is because the betacyanin pigment of beet root cells is normally sequestered in the vacuole and by means of the cell membrane which maintains the integrity of the cell and the tonoplasts, it does not leak into the cytosol or the extra-cellular sap of the beet root. However when we increase the temperature the relatively weak forces holding the different parts of the polypeptide chains together (like hydrogen bonds, sulphur bridges and ionic bonds) can be disrupted very easily- this damages the vacuole and makes holes in the cell membrane, inducing leakage.
The cell membrane is also damaged and so diffusion of betalain occurs through the partially permeable membrane by osmosis- the betalain molecules move by diffusion from an area where they are more highly concentrated to an area where they are at a lower concentration, along a concentration gradient.
The reason why the amount of betalain pigment increases rapidly (from 40 C to 60 C) is because most mammalian protein's denature and tertiary structure unravels (the strong covalent bonds between the R groups of amino acids in the polypeptide chains are destroyed) at temperatures over 40 C. Thus significant jump is explained.
The reason why the curve starts to flattens out (between 60 C and 70 C), is because although the denaturing of the protein causes a rapid rise in the amount of betalain released to start with, when the temperatures begin to get higher still, the protein's tertiary structure blocks some of the holes in the cell membrane and therefore slows down the release of betalain.
At 0 C relatively no energy is available to molecules therefore values for colorimeter reading were significantly low.
Evaluation
There were a number of sources of error that may have affected the accuracy of my results.
Firstly I had one stopwatch and timed all the water baths for fifteen minutes, so was a slight delay however between the placing of the tubes in each water bath, as I had to walk to each water bath so it would have affected my results slightly. This would only have had a small effect on my results, because the vacuole of the beetroot would have only released slightly more betalain, as the molecules would have only had a very small amount more heat energy to convert into kinetic energy.
Secondly I when I washed each of the beetroot pieces I may not have removed all of the red pigment on the outside, so this would have affected my results very slightly. Again this would only have had a small effect on my results, because a very slight increase in betalain molecules would not have changed the reading on the …show more content…
colorimeter.
There were also limitations of my experiment.
Firstly I only had an hour in which to conduct my experiment- this did not give me time to collect a sufficient number of results. A larger number of results taken at different temperatures between 20oC and 60oC would have allowed me to find out more accurately where the point of denaturising occurred.
It would also have been better to have had the time to repeat each temperature more times to make the results more reliable and so I could be sure the results were not gained through chance. This may have eliminated my anomaly, but I did repeat the experiment twice and the two results on each temperature were almost identical, so this would have had very little effect on the accuracy of my results.
Another limitation was cutting the beetroot into pieces. The pieces cut had roughly the same surface area to volume ratio- but not exactly the same. This would have had a slight effect on my results because the rate of diffusion of betalain particles across the plasma membrane is increased, as the surface area of the beetroot increases. So the slightly thinner and smaller pieces of beetroot I cut would have released more betalain from their
vacuole.
I only looked at one type of plant cell, so I can not be sure that every plant cell and indeed eukaryote- which have different plasma membranes that may be adapted to cope with heat better or worse than beetroot cells will have the same results.
I can firmly conclude that there are no apparent anomalies in my results and none of my sources of error or limitations of my experiment are enough to deem my results unreliable. However the sources of error and limitations in my results may have made my results slightly less accurate, but other students in my class found the same patterns occurring and roughly the same results- which would vary slightly between each beetroot anyway.
PLAN
Hypothesis
Temperature has an effect on the leaking of the colour from beetroot. This means that as the temperature is altered there will be a change in the rate of colour leakage.
Scientific Background
Beetroot is a very familiar vegetable and is commonly known as beet. It is famous in most recipe books that advice that its outer skin is not to be removed to avoid getting red dye in the cooking water.
If we look at the internal structure of beetroot, it will be observed that it consists of cells which are surrounded by a cell membrane. This cell membrane structure separates the contents of the cell from outside. The membrane has tiny holes in it which allows small molecules to pass …show more content…
through but not larger ones. This is known as semi-permeability. Beetroot contains red pigments called betalains in the cell vacuole and normally do not pass through the membrane. However when cooked, the dye leaks out and so I am investigating the effect of different temperatures on the amount of dye and the extent of damage on the beetroot membrane structure which causes the holes to allow larger molecules through. For molecules to move as a whole, they require a certain amount of energy. This energy may be supplied in the form of heat. Heat energy can be measured as temperature which is the degree of hotness or coldness of a body. It can be predicted that as temperature increases, the reading of the colorimeter will increase since betalain molecules will acquire enough energy to move through the membrane by active transport. There is also the possibility of temperature affecting pore size. As temperature increases, pore size increases.
The colorimeter reading will implicate how much of the betalain has moved out through the membrane since that amount is directly proportional to colour given out.
Procedure
Cut Sections from a single beetroot using a size 4 cork borer. Cut eight, 1cm length slices from these sections. Be careful not to spill beetroot juice on skin or clothing as it will stain very badly.
Place the slices in a beaker of distilled water. Leave overnight to wash away excess dye.
Next day place eight labelled boiling tubes each containing 5 cm distilled water into water baths at 0 C, 10 C, 20 C, 30 C, 40 C, 50 C, 60 C and 70 C. Leave for 5 minutes until the water reaches the required temperature. Place one of the beetroot sections into each of the boiling tubes. Leave for 30 minutes in the water baths.
Decant the liquid into a second boiling tube or remove beetroot sections using a technique that does not squeeze the slice e.g. spear with a pointed seeker. Shaker the water/solution to disperse the dye.
Switch on the colorimeter and set it to read % absorbance.
Set the filter dial to the blue/green filter.
Using a pipette accurately, measure 2 cm distilled water into a cuvette. Place the cuvette into the colorimeter, making sure that the light is shining through the smooth sides.
Adjust the colorimeter to read 0 absorbance for clear water. Do not alter the setting again during the experiment.
Place 2 cm of the dye solution into the colorimeter cuvette and take the reading for the absorbency. Repeat the readings for all the temperatures.
Present results in an appropriate way.
Identify any trends or patterns in your results.
The variables kept constant
The same diameter corer is used so to keep the surface area of each beetroot piece the same size.
The dependant variable was temperature since it was altered in each experiment.
When the beetroot has been cut some of the cell membranes is broken, which means some anthocyanin will leak out. This must be completely washed off in order to maintain the reliability of the results.
I will use distilled water to so that I have a reliable substance to test with a colorimeter.
Excess dye was washed out overnight to ensure more accurate and fair results.
Measurements
Reading of colorimeter was set as that of the empty cuvette to remove the possibility of percentage error.
Accuracy
Water in test tubes will be heated for 5 minutes to obtain the required temperature before beetroot is added.
All beetroot will be cut into the exact same size with a knife to ensure a fair test
Water bath will be lagged to reduce amount of heat being lost to the environment.
Cuvette will be placed into colorimeter with transparent side facing the internal light.
Cuvette will be filled to the top mark by liquid obtained from beetroot.
Each temperature experiment is conducted with 3 test tubes to find the average to ensure accurate results.
Risk assessment
Care will be taken whiles using cork borer and water bath at temperature of 70 C.
REPORT
Change in Procedure
Slices were left overnight the day before to wash away excess dye since time to conduct experiment was limited.
Temperatures 10 C and 30 C were not used in the experiment to save time.
Knife was used instead of cork borer since it wasn’t available at the time.
Discussion
As temperature increased, the reading on the colorimeter increased.
Lowest reading was recorded at temperature of 0 C.
Highest reading on colorimeter was recorded at temperature of 70 C
Amount of pigment released increased with an increase in temperature.
5. There was a gradual increase from temperatures 0 – 40 C, with a significant jump to 50 C.
Explanation of results
The reason why the amount of betalain pigment released (colorimeter reading) from the vacuole increased directly proportionally to the temperature of the water bath (from 20 C to 40 C) is because the amount of random movement of betalain molecules out through the cell membrane depends on the amount of heat energy the betalain molecules are given to convert into kinetic energy- hence the higher the temperature the more betalain lost from the vacuole.
This is because the betacyanin pigment of beet root cells is normally sequestered in the vacuole and by means of the cell membrane which maintains the integrity of the cell and the tonoplasts, it does not leak into the cytosol or the extra-cellular sap of the beet root. However when we increase the temperature the relatively weak forces holding the different parts of the polypeptide chains together (like hydrogen bonds, sulphur bridges and ionic bonds) can be disrupted very easily- this damages the vacuole and makes holes in the cell membrane, inducing leakage.
The cell membrane is also damaged and so diffusion of betalain occurs through the partially permeable membrane by osmosis- the betalain molecules move by diffusion from an area where they are more highly concentrated to an area where they are at a lower concentration, along a concentration gradient.
The reason why the amount of betalain pigment increases rapidly (from 40 C to 60 C) is because most mammalian protein's denature and tertiary structure unravels (the strong covalent bonds between the R groups of amino acids in the polypeptide chains are destroyed) at temperatures over 40 C. Thus significant jump is explained.
The reason why the curve starts to flattens out (between 60 C and 70 C), is because although the denaturing of the protein causes a rapid rise in the amount of betalain released to start with, when the temperatures begin to get higher still, the protein's tertiary structure blocks some of the holes in the cell membrane and therefore slows down the release of betalain.
At 0 C relatively no energy is available to molecules therefore values for colorimeter reading were significantly low.
Evaluation
There were a number of sources of error that may have affected the accuracy of my results.
Firstly I had one stopwatch and timed all the water baths for fifteen minutes, so was a slight delay however between the placing of the tubes in each water bath, as I had to walk to each water bath so it would have affected my results slightly. This would only have had a small effect on my results, because the vacuole of the beetroot would have only released slightly more betalain, as the molecules would have only had a very small amount more heat energy to convert into kinetic energy.
Secondly I when I washed each of the beetroot pieces I may not have removed all of the red pigment on the outside, so this would have affected my results very slightly. Again this would only have had a small effect on my results, because a very slight increase in betalain molecules would not have changed the reading on the …show more content…
colorimeter.
There were also limitations of my experiment.
Firstly I only had an hour in which to conduct my experiment- this did not give me time to collect a sufficient number of results. A larger number of results taken at different temperatures between 20oC and 60oC would have allowed me to find out more accurately where the point of denaturising occurred.
It would also have been better to have had the time to repeat each temperature more times to make the results more reliable and so I could be sure the results were not gained through chance. This may have eliminated my anomaly, but I did repeat the experiment twice and the two results on each temperature were almost identical, so this would have had very little effect on the accuracy of my results.
Another limitation was cutting the beetroot into pieces. The pieces cut had roughly the same surface area to volume ratio- but not exactly the same. This would have had a slight effect on my results because the rate of diffusion of betalain particles across the plasma membrane is increased, as the surface area of the beetroot increases. So the slightly thinner and smaller pieces of beetroot I cut would have released more betalain from their
vacuole.
I only looked at one type of plant cell, so I can not be sure that every plant cell and indeed eukaryote- which have different plasma membranes that may be adapted to cope with heat better or worse than beetroot cells will have the same results.
I can firmly conclude that there are no apparent anomalies in my results and none of my sources of error or limitations of my experiment are enough to deem my results unreliable. However the sources of error and limitations in my results may have made my results slightly less accurate, but other students in my class found the same patterns occurring and roughly the same results- which would vary slightly between each beetroot anyway.