Differences in the Protein,
Carbohydrate, and Caffeine content of Black Tea and Coffee
By:Ê
Michael Chen, Robert Fedorow, Meghan Lee, and Michelle Mahoney
LBS 145
Lab Tuesday 1
Dr. Fata-Hartley
Abstract:
Robert Fedorow
Revised by Michelle
Mahoney
Second Revision by
Meghan Lee
ÊÊÊÊÊÊÊÊÊÊÊ Coffee and tea are two of the most popular drinks for people to consume in order to wake up or stay awake.Ê While so many people drink coffee and tea for the caffeine, they do not normally think about the other substances that make up the two beverages.Ê Some other components of the drinks may include proteins, carbohydrates and amino acids.Ê This experiment plans on finding the different amounts and the different kinds of these substances in coffee and tea using different known tests.Ê To find the different amounts of proteins the Bradford Assay was used.Ê For carbohydrates, there are a series of tests to distinguish if coffee and tea contain glucose, starch or some other coiled polysaccharide, monosaccharides, and/or ketoses: using the iodine test, Barfoedâs test, and Selivanoffâs test respectively.Ê The glucose level was found by using a glucose meter.Ê To find whether coffee or tea contain more caffeine per unit volume, caffeine was isolated from both of them through several extractions.Ê To test which drink contains more kinds of amino acids an amino acid chromatography was conducted.Ê It was found that both tea and coffee contained monosaccharides, ketoses and starch. The protein level of coffee was much higher than that of protein and more amino acids were found in tea while only 3 were found in coffee. During the isolation of caffeine test, tea showed to have more caffeine than coffee but errors did arise. The hypothesis stated that tea would be a healthier substitute for coffee because it would have more protein, fewer carbohydrates and less caffeine than coffee. The results show that tea contains less protein, more caffeine and the same amount of carbohydrates than coffee.
Introduction:
Robert Fedorow and
Michelle Mahoney
Revised by Michelle
Mahoney
Second Revision by
Meghan Lee
ÊÊÊÊÊÊÊÊÊÊÊ Coffee
is one of the most commonly drank beverages in Western culture and probably the
world (Halvorsen, 2005).Ê This is due to
the caffeine contained in it that stimulates Îpsychomotor speedâ (Luciano,
2003). Psychomotor speed can also be defined as the ability to rapidly and
fluently perform body motor movements independent of cognitive control. Caffeine
is the reason for this unhealthy habit; in accordance, most of the caffeine
consumed in the
ÊÊÊÊÊÊÊÊÊÊÊ The other molecules which make up coffee that will be tested in this experiment, besides amount of caffeine per unit volume, are carbohydrates, proteins, and amino acids.Ê To see if there is a better alternative to coffee, composition of tea will be compared in each of the stated categories.Ê Tea is known for being a healthy drink for many reasons, mostly due to its beneficial effects dealing with antioxidants, yet still contains caffeine and hopefully many of the same kind of compounds as coffee (Rietveld, 2003).Ê From research it is known that polysaccharides in tea actually promote good health (Chenghong, 2001).Ê The risk of cancer is reduced, heart disease and high blood pressure is prevented, lowers cholesterol and blood sugar levels and it fights against aging. Some of these comparative experiments will test for specific compounds quantitatively, while others will only see qualitatively if coffee or tea contains the broader category of the molecule.Ê The coffee and tea will be compared in hopes to find out similarities and differences of their composition pertaining to carbohydrates/sugars, proteins, amino acids, and caffeine with expectation that tea may be a very similar yet healthier substitute for coffee.
The first of the quantitative tests will be to find out how much glucose the specific beverage contains by using a glucose meter.Ê Glucose is used as a source of energy and as a metabolic intermediate in cells.Ê It is necessary for cells, but can show drastic consequences if too much is ingested (Anonymous-1, 2006). A few consequences include diabetes, blurred vision or permanent damage to the eyes, heart attack or stroke and damage to kidneys, nerves, and blood vessels.Ê Researcher Sheldon Reiser has done research on the effects of carbohydrates and has shown that simple sugars could cause heart disease or diabetes (McBride, 1991). ÊThe second carbohydrate test is the Iodine test for starch.Ê This will show if either, both, or neither coffee and tea contain starch.Ê This test as well as Barfoedâs test and Selivanoffâs test will hopefully help to distinguish between different carbohydrate compounds that compose the tea and coffee, but are only qualitative.Ê Barfoedâs test will illustrate if the drinks contain monosaccharides, while Selivanoffâs test will verify if ketoses are present.
The next quantitative test will be for protein.Ê Amino acids contained in proteins have many beneficial effects such as being antioxidants, antidepressants, and energy boosters. If not enough of these acids are consumed, hypoglycemia, allergies, or depression could occur (Anonymous-3, 2006).Ê It is also true though that the most Americans ingest too much protein which is detrimental to ones health.Ê The Bradford Assay will determine if there is a difference in the amount of protein between coffee and tea by making a standard curve which is used to determine unknown protein amounts and comparing it with the results.Ê From here the building blocks of these proteins will be tested: amino acids.Ê Amino acid chromatography will be used in order to find out if there is a difference in the different types of amino acids present in the drinks, again to find how similar coffee and tea are in this aspect of their composition.Ê
Lastly, and possibly the most important test in this experiment, will be the isolation of caffeine to be sure that tea is able to provide people with a reasonable amount of caffeine as compared to coffee.Ê On average, one serving of brewed coffee typically contains 80-135mg of caffeine, while in comparison, Mountain Dew has only 55mg, and tea a mere 40mg.Ê A general consensus is that a moderate amount of caffeine is 300 mg each day (Anonymous-2, 2006). Too much caffeine consumption can cause negative consequences. Caffeine can affect hormones such as adenosine, adrenaline, coritsol and dopamine. Sleep and a personâs weight can also be affected. If tea is not comparable to coffee in terms of amount of caffeine per unit volume then it will be a suitable substitute for coffee, rendering our hypothesis valid.
With the
experiments, it is predicted that tea will prove to be a healthier substitute
for coffee.Ê It was hypothesized that tea
will have less protein, fewer carbohydrates, and less caffeine than
coffee.Ê With the Barfoed and Selivanoff
tests, it will be possible to show that coffee may contain more types of
carbohydrates than tea.Ê The Iodine test
can then support the presence of starch in coffee.Ê The glucose meter showed that only tea
contained a significant amount of glucose; coffee did not show up on the
meter.Ê Using the
Methods:
Meghan Lee
Revised by Robert Fedorow
Second Revision by Michael
Chen
Preparation of Materials
In this specific experiment coffee and tea were
tested. The coffee was Maxwell House Coffee Singles and the tea was Orchestral
Tea, Orange Pekoe Black tea. The coffee was purchased at the Meijer on
ÊÊÊÊÊÊÊÊÊÊÊ To create a coffee solution, seventy-five milliliters of distilled water were placed in a beaker with a coffee singles and then warmed on a hot plate for 10 minutes. To create a tea solution, the process was repeated but a tea packet was substituted for the coffee. After the coffee and tea solutions were complete several tests were performed.
Barfoedâs Test
The Barfoedâs test is used to distinguish between monosaccharides, disaccharides and polysaccharides. A rusty-red color indicates the presence of monosaccharides. A slight change in color or no color change indicates the presence of di- and polysaccharides. This test will determine which type of sugar is present in coffee and tea. For this test one percent xylose solution was used as a positive control, one percent lactose was used as a negative control, and distilled water served as a mock control. Five hundred µl of coffee, tea, xylose, lactose and distilled water were added to separate test tubes. Three milliliters of Barfoedâs solution were then added to each test tube. The tubes were placed in a boiling water bath and observations were made after one minute and continued for two minutes. The coffee and tea were then tested an additional two times for a total of three trials.
Selivanoffâs Test
Selivanoffâs test is used to distinguish between aldoses and ketoses. A rapid color change (within one to two minutes) indicates the presence of a ketose while a much slower color change (requiring several minutes) indicates the presence of an aldose. For this test one percent fructose solution was used as a positive control, one percent galactose was used as a negative control, and distilled water was used as a mock trial. Three hundred fifty microliters of coffee, tea, fructose, galactose and distilled water were placed in separate test tubes.Ê Three milliliters of Selivanoffâs reagent were then added to each tube. The tubes were placed in a boiling water bath where the time it took for each tube to change color was recorded. The coffee and tea were then tested an additional two times for a total of three trials.
Iodine Test
The Iodine test is used to distinguish starch from monosaccharides, disaccharides, and other polysaccharides. A bluish black color change indicates the presence of starch while no color change indicates the presence of no starch. This test will help determine which components are present in coffee and tea. For this test six percent starch solution was used as a positive control, six percent lactose solution was used as a negative control, and distilled water was used as a mock control. Three hundred fifty microliters of coffee, tea, starch, lactose and distilled water were placed in separate test tubes. Thirty-five microliters of IKI reagent were then added to each tube. Diluting the coffee and tea may be required to observe changes. Color changes to the tubes were observed at room temperature.
Glucose Meter
A five microliter drop of coffee was placed on the glucose meter test strip.Ê The test strip was then inserted into the glucose meter.Ê The machine gave a reading of the glucose content in mg/dL. This procedure was done three times for both the tea and coffee.
Amino Acid Chromatography
The chromatography plate that was used was about fifteen to twenty centimeters in length and about three centimeters in width. A pencil line (the origin line) was drawn about one centimeter from the bottom across the width and another line ten centimeters above this line, again horizontally. Then, a fine-tipped paint brush was used to paint a thin line of the coffee just above the origin line on the chromatography plate. The coffee line was darkened with several more strokes of the brush. After this was done, the plate was set aside. The next part involved making the chamber, which was done by first placing the mobile phase (n-Butanol-acetic acid-water (80:20:20)) in a large test tube about one and a half centimeters from the bottom. Once the tube contained the mobile phase, it was corked, shaken, and then left alone for ten minutes to equilibrate. After that, the chromatography plate was set in the chamber carefully without the coffee line touching the solvent front.Ê It took approximately two and a quarter hours for the plate to develop.Ê It was done when the solvent front reached the line ten cm from the origin line.Ê As soon as the plate was complete it was taken out of the chamber and sprayed with a five percent ninhydrin solution.Ê Immediately after spraying the plate, it was placed in the oven at sixty degrees Celsius for thirty minutes.Ê Once taken out of the oven, the most darkened spot traveled by each amino acid was measured. To obtain the RF value, this distance was divided by the distance the solvent had moved. The RF value then correlated to different types of amino acids.Ê Which amino acids were in the solutions were found using an amino acid RF value chart.Ê This entire procedure was repeated three times for coffee, three times for tea, and one time for Sigma-Aldrichâs amino acid standard solution (which contained twenty amino acids).
Protein (
This test determines protein concentration in tea
and coffee, which is significant in our experiment because it helps determine
which one is more nutritious.
The first part involved obtaining a standard curve by a series of dilutions. This was done by first placing two milliliters of the two milligrams/milliliter bovine serum albumin (BSA) in a test tube labeled 2. Then, six other test tubes were obtained, labeled 1, 0.5, 0.25, 0.125, 0.0625, and 0, and contained one ml of ddH2O. ÊNext, one milliliter of the BSA in test tube 2 was pipetted into test tube 1. Afterward, the test tube was vortexed and the pipette tip was discarded. As this was finished, one milliliter of the solution in test tube 1 was pipetted into test tube 0.5. Again, the tube was vortexed and the pipette tip was discarded. This process was continued for test tubes 0.25, 0.125, 0.0625, each time obtaining one milliliter of solution from the previous test tube and placing it in the next one. Test tube 0 was left alone and used as the blank.
The second part involved reading the absorbance of each of the labeled test tubes.ÊÊ To do this, 50 ml of a particular sample were placed in an empty test tube. Next, 50 ml of 0.1 M NaOH were added, vortexed and left for five minutes. Soon, three ml of Bradford Reagent were added to the test tube, vortexed and left alone for five minutes. Finally, the absorbance of the solution was read at 595 nm and recorded. This was also the same procedure in determining the absorbance of coffee and tea.
The third part involved finding the protein concentration in tea and coffee. So first, a graph depicting Concentration of BSA vs. Absorbance was plotted. The equation for the best-fit line of the graph was obtained which was used to calculate protein by first finding the concentration of BSA of the corresponding absorbance. Finally, the protein content was found by multiplying the BSA Concentration by the volume of the sample (Coffee or Tea) used.ÊÊÊÊÊÊÊ
Isolation of Caffeine
ÊÊÊÊÊÊÊÊÊÊÊ In organic chemistry this procedure was used to isolate caffeine from a tea bag. The procedure will also help to distinguish the amount of caffeine present in coffee compared to that present in tea. A tea bag was placed in a beaker with seventy-five milliliters of water.Ê The beaker was covered with a watch glass and heated on a hot plate until just before boiling for about 15 minutes making sure the tea bag stayed under the water.Ê Any water that evaporated was replaced to approximately maintain the original seventy-five milliliters of water.Ê After 15 minutes the concentrated tea solution was transferred in 2 equal volumes to 2 test tubes.Ê One half gram of sodium carbonate was added to each tube, then capped and shaken until all solid dissolved.Ê This tea solution was allowed to cool to room temperature using an ice bath.Ê Then three milliliters of dichloromethane was added to each tube.Ê These tubes were capped again and shaken gently for several seconds while being vented every once in a while.Ê These mixtures were then centrifuged to break the emulsion that formed.Ê The lower organic layer was removed with a pipette and transferred from both tubes into a third clean and empty tube.Ê It was made sure that none of the dark aqueous solution was transferred with this organic solvent.Ê A fresh three milliliter portion of dichloromethane was added to the aqueous layers and the extraction was repeated.Ê It was better to leave some of the organic layer behind than if some had gotten into the aqueous layer.Ê This organic layer was dried in the third tube by adding a small amount of anhydrous sodium sulfate.Ê The ãdryä organic layer was transferred to a clean pre-weighed filter flask.Ê In this filter flask the dichloromethane was evaporated by heating the flask in a hot water bath.Ê When the solvent evaporated only the solid caffeine was left on the bottom of the flask.Ê This flask was weighed while containing the caffeine as well as empty to get the mass of the crude caffeine.Ê This entire procedure was repeated three times for the coffee bag and three for the tea bag.
Results:
Meghan Lee
Revised by Robert Fedorow
Second Revision by Michael Chen
Barfoedâs Test
ÊÊÊÊÊÊÊÊÊÊÊ During the Barfoedâs test, the coffee and the tea turned a rusty red color and formed a precipitate indicating the presence of monosaccharides in both (Figure 2).
Selivanoffâs Test
ÊÊÊÊÊÊÊÊÊÊÊ During
the Selivanoffâs test, the coffee and the tea turned a reddish color within 2
minutes, indicating the presence of ketoses (Figure 3).
Iodine Test
ÊÊÊÊÊÊÊÊÊÊÊ During the Iodine test, the coffee and the tea turned a dark, bluish black color and formed a precipitate. This precipitate was most likely due to a complex that is formed between the iodine and starch and indicated the presence of starch (Figure 4).
Glucose Test
ÊÊÊÊÊÊÊÊÊÊÊ While conducting the glucose test, only the tea gave a measurable reading of 38, 41, and 42 mg/dL for trial 1, 2, and 3 respectively.
Amino Acid Chromatography
ÊÊÊÊÊÊÊÊÊÊÊ Conducting the Bradford Assay showed that coffee contained more protein than tea. Our initial testing results are shown in Tables 1, 2, and 3: coffee, tea, and an amino acid standard solution respectively. From these results, the tea contained seven to eight different amino acids whereas the coffee only contained three types.Ê
Protein (
ÊÊÊÊÊÊÊÊÊÊÊ BSA concentration and absorbance were plotted on a graph (Figure 1) and using the equation for line of best fit it was determined that coffee contained more protein than tea.Ê Figure 5 shows that our average protein amount for tea was 4 μg/serving, while it was 30 μg/serving for coffee.Ê
Isolation
of Caffeine
The caffeine content for three trials of coffee was 0.024, 0.009, and 0.024 g/serving whereas it was 0.023, 0.028 and 0.011 g/serving for tea. Comparing the averages, the tea contained more caffeine per serving than the coffee (Table 4).
Discussion:
Michael Chen
Revised By: Robert Fedorow
I.
Summary of Introduction
● Coffee is a beverage that is widely consumed in our world, however it contains caffeine, a substance which has been known to cause negative health effects if taken in excess amounts (typically above five-hundred milligrams per day).Ê Such detrimental health effects of caffeine if taken in the excess amount include anxiety, sleep disruption, irritability, increased heart rate, and upset stomach. (Anonymous-7, Unknown)
ÊÊÊÊÊÊÊÊÊÊÊ ● Even though tea also contains caffeine, it has some beneficial effects
ÊÊÊÊÊÊÊÊÊÊÊ because its antioxidants, polysaccharides, and flavonoids are known toÊÊ
ÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊ promote good health. (Rietveld, 2003)
ÊÊÊÊÊÊÊÊÊÊÊ ● Coffee and tea will be compared to find out which one is the moreÊÊ
ÊÊÊÊÊÊÊÊÊÊÊ nutritious beverage in terms of carbohydrates (qualitatively- starch,
ketose or aldose, monosaccharide or polysaccaride, quantitatively- glucose), protein content (quantitatively), amino acid composition (qualitatively- presence of particular amino acids), and caffeine content (quantitatively).
● Tea is predicted to be more nutritious than coffee because tea is known to have health benefits. Due to this, it is assumed that tea will contain more protein, less glucose, fewer kinds of carbohydrates, less caffeine per volume, and more variety of amino acids than coffee.Ê
II.
Summary of Results
● Carbohydrates- Overall the sugar tests were not able to differentiate the nutritional composition between coffee and tea as most of the tests gave the same result for both.Ê Due to this indifference we are not able to accept or refute out hypothesis as pertaining to carbohydrates, requiring quantitative tests of the carbohydrates contained in coffee and black tea.
ÊÊÊÊÊ 1. Barfoedâs Test: Both contained monosaccharides.
ÊÊÊÊÊ 2. Selivanoffâs Test: Both
contained ketoses.
ÊÊÊÊÊ 3. Iodine Test: Both contained
starch.
ÊÊÊÊÊ 4.
Glucose Test: The meter read teas
glucose content but was unable toÊ
give coffees.Ê
We believe this to mean that the amount of glucose in coffee was too low
for the meter to read.Ê In this case this
single test would help to disprove our hypothesis, but as with the other tests
would need to be further investigated since we do not know for sure coffees
glucose level being low was the reason for the meter malfunction.
● Proteins- Coffee contained a lot more protein than tea, on average 26.33
micrograms more per microliter.Ê This research supports our hypothesis that coffee contains more protein than tea.Ê As stated in the introduction, this adds to coffee being an unhealthy drink since the average American takes in more than the daily recommended allowance of protein a day, so decreasing this amount would be beneficial to most Americans health.
● Amino Acid- Tea contained a variety of amino acids whereas coffee only
contained three.Ê Our reasoning that whichever beverage has higher protein content would have the more diverse array of amino acids was refuted by our results.Ê We can explain this in that amino acids themselves have many health benefits (already stated in the introduction) which would make sense for more of them to be in tea, since we hypothesized it would contain a composition better for ones health than coffee.
● Caffeine- Our results as a whole would appear to say that there is slightly more caffeine on average in black tea than in coffee.Ê This does not
coincide with numerous studies or our hypothesis.Ê We can account for such disagreement due to two problems that occurred in our experimentation.Ê The first problem occurred in one of the coffee trials.Ê The flask containing pure caffeine was left on the hot plate for too long while the organic solution was evaporating off of it since the solution evaporates extremely fast once it gets very low.Ê This caused some of the caffeine to sublime, decreasing the overall mass of that container of caffeine by over fifty percent.Ê In two of the tea trials the boiling stones preventing the tea from boiling out of the flask dissolved in the organic solution.Ê This is extremely strange, for the boiling stones we used state that they only dissolve in highly acidic or basic solutions (neither of which the stones were in).Ê There has been no found research as to why this occurred.Ê With these problems taken into account our reconfigured results yield over twice as much caffeine in coffee as in black tea. (Table 4)Ê These new results support previous research and our hypothesis that coffee contains significantly more caffeine than tea.
III.ÊÊÊÊÊÊ ÊÊInterpretation
of Results (relating to prior research)
ÊÊÊÊÊÊÊÊÊÊÊ ● Carbohydrates
ÊÊÊÊ a. (Anonymous-4, 2005): This site gives information on how some carbohydrates can be health-benefiting by providing the body with fuel for proper organ functioning and physical activity while others (when consumed in large quantities) can increase risk for diabetes and coronary heart disease. Therefore, carbohydrates in tea and coffee can be described as beneficial or harmful depending on the quantity consumed.
ÊÊÊ b. (Matthews et al., 1987): This report gives data on the monosaccharide (galactose, glucose, fructose), polysaccharide (lactose, sucrose, maltose) and total sugar content in coffee and tea. Therefore, the experimental results can be used to compare with the USDAâs results to either further support the carbohydrate composition in tea and coffee or to suggest reasons for the contradicting results.
●
Proteins
ÊÊÊÊÊ a. (Anonymous-2, Unknown): This USDA database will be used to compare the protein results for coffee and tea with theirs. If the data (coffee has more protein than tea) is consistent with theirs, it just further confirms the fact that coffee contains more protein and allows the team to suggest a reason for the result and refute the hypothesis (tea contains more protein). On the other hand, if the data is conflicting with the USDAâs, a paragraph will describe what might have went wrong, and what could have been done better.ÊÊÊÊ
ÊÊÊÊ b. (Anonymous-3, 2004): The site gives an
overview of how important proteins are to the body. Therefore, it is possible
to connect the beverage that contained more protein to be the more nutritious
one since the lack of it in the body can lead to growth failure, loss of muscle
mass, etc.
● Amino
Acid
a. (Adderly, 1999):Ê The article gives general information as to why amino acids are important to good health and how they relate to proteins. Since amino acids make up proteins, an explanation will describe the fact that tea has a variety of amino acids, yet lower protein content, while coffee has only three kinds of amino acids, yet higher protein content.ÊÊ
ÊÊÊÊ b. (Anonymous-5. 2004): This
article lists the names of some amino acids and gives the function of each.
Since the team found the amino acids that show up best on a TLC plate in tea,
coffee, and a standard solution containing all of them, the article gives
information on what some particular ones actually do. Therefore, this would
help greatly in determining which beverage is healthier and more nutritious,
except we found after we got our results that none of the amino acids in coffee
or tea were on the list.Ê Two of the
amino acids we found in the standard solution were on the websiteâs list
though: cysteine and lysine, helping with osteoarthritis and osteoporosis
respectively.
● Caffeine
a. (Barone and Roberts, 1996): This paper addresses the caffeine content of food/drugs and the decrease of caffeine consumption over time, so this can be used to describe that the public becoming more aware of the negative health effects correlated with caffeine and are more careful in what they consume.
b. (Chou, 1992):
This reference will be used to describe the negative effects of caffeine.
Therefore, it will be possible to describe how the beverage with more caffeine
is less nutritious since caffeine can lead to its addiction and increase in
fatty acid secretion.
IV.ÊÊÊ ÊÊÊÊÊAfter Thoughts
● While the errors that were experienced in the
extraction of caffeine stated in the Summary of Results Section were the only
actual errors in this experiment there are several follow-up procedures that
should be carried out.Ê
● With respect to the carbohydrate tests,
future experimentation should be done to find out the quantity differences of
carbohydrates in coffee and tea.Ê Since
our data was qualitative it appeared the same for all the carbohydrate tests,
leaving us without differentiating data.Ê
● The other test that should be redone slightly
modified is the amino acid chromatography.Ê
Our TLC plates came out more streaked rather than in definitive lines
for the different amino acids than we would have liked.Ê We feel we could correct this by allowing the
running solvent to travel much further before taking the TLC plates out of the
saturation chambers and by using a spray bottle for the five-tenths percent
ninhydrin solution with a finer mist than the one we had.Ê Those two changes should allow us to
differentiate among more amino acids in the coffee and tea and should yield
closer actual RF-values to the experimental ones.Ê
● Lastly, we would repeat the caffeine
experiment making sure not to make the same mistakes as this time.Ê To do this we would use a taller flask
instead of a boiling stone.Ê This would
get rid of ability for the boiling stone to dissolve since it would not be in
the container at all, yet the taller container would stop boiling solution from
shooting caffeine out of the flask.Ê Secondly,
we would be sure to take the flasks off of the hot plate well before the
organic solution was fully evaporated and allow it to evaporate off of the hot
plate.Ê This would allow the flask to be
cool enough when the solution was fully evaporated to not allow for any
caffeine to sublime.
Figures and Tables:
Michael Chen
Revised by Meghan Lee
Second Revision by
Michelle Mahoney
ÊÊÊÊÊÊÊÊÊÊÊ Figure 1:
Graph plots BSA concentration vs. Absorbance at 595 nm for the Bradford Assay.
A linear fit line was added and the equation y = 1.5518x-0.1972 was used to
determine the protein content in the tea and coffee samples.Ê It was found that coffee contained more
protein content than tea.
ÊÊÊÊÊÊÊ T1ÊÊÊÊÊÊ T2ÊÊÊÊÊÊ T3ÊÊÊÊÊ T4ÊÊÊÊÊÊ T5ÊÊÊÊÊÊ T6ÊÊÊÊÊÊ T7ÊÊÊÊÊÊ T8ÊÊÊÊÊ T9
Figure 2: Samples for Barfoedâs Test. Pictured from left to right: T1 - mock control (distilled water), T2 - positive control (xylose), T3 - negative control (lactose), three trials of tea: T4, T5, T6 and then three trials of coffee: T7, T8, T9.Ê During the Barfoedâs test, the coffee and the tea turned a rusty red color and formed a precipitate indicating the presence of monosaccharides.
ÊÊÊÊ T1ÊÊÊ T2ÊÊÊÊ
T3ÊÊÊÊ T4ÊÊÊ T5ÊÊÊÊ
T6ÊÊÊ T7ÊÊÊ T8ÊÊÊÊ
T9ÊÊÊ T10ÊÊ T11
Figure 3: Samples for Selivanoffâs Test. Pictured from left to right: T1 - mock control (distilled water), T2 - coffee in Selivanoffâs solution, T3 - tea in Selivanoffâs solution, T4 - negative control (galactose), T5 - positive control (fructose), T6 - tea after 10 minutes, T7 - coffee after 10 minutes, T8 and T9 - tea after five minutes and T10 and T11 - coffee after five minutes. During the Selivanoffâs test, the coffee and the tea turned a reddish color within 2 minutes, indicating the presence of ketones.
T1ÊÊÊÊÊÊ T2ÊÊÊÊÊÊ T3ÊÊÊÊÊÊ T4ÊÊÊÊÊ T5ÊÊÊÊÊÊ T6ÊÊÊÊÊ T7ÊÊÊÊ
T8ÊÊÊÊÊ T9ÊÊÊ T10ÊÊ
T11
Figure 4: Samples for Iodine Test. Pictured from left to right: T1 - mock control (distilled water); T2 - plain tea; T3 - plain coffee; T4 - negative control (lactose); T5 positive control (starch); T6, T7, T8 tea trials; T9, T10, T11 coffee trials. During the Iodine test, the coffee and the tea turned a dark, bluish black color and formed a precipitate. This indicated the presence of starch.
Tea Trials Coffee Trials
Figure 5: Results for the Bradford Assay comparing protein amounts in coffee and tea.Ê It can be seen that on average coffee contained a higher protein concentration than tea.
Table 1: Performing the Amino Acid TLC test gave possible
amino acids present in coffee
|
Coffee Average (Rf value) |
Amino Acid |
Known Rf for n ö Butanol ö acetic acid -
water |
|
0.187 |
Pro |
0.212 |
|
0.290 |
|
0.288 |
|
0.303 |
|
0.288 |
Table 2: Performing the Amino Acid TLC test gave possible amino acids present in tea
|
Tea Average (Rf value) |
Amino Acid |
Known Rf for n ö Butanol ö acetic acid -
water |
|
0.190 |
Pro |
0.212 |
|
0.250 |
Ser |
0.241 |
|
0.327 |
|
0.288 |
|
0.407 |
Val |
0.412 |
|
0.473 |
Ile |
0.471 |
Table 3: Performing the Amino Acid TLC test gave possible amino acids present in the standard solution
|
Standard Solution (Rf value) |
Amino Acid |
Known Rf for n ö Butanol ö acetic acid -
water |
|
0.07 |
His Cys |
0.071 |
|
0.12 |
Arg |
0.100 |
|
0.17 |
Pro |
0.212 |
|
0.25 |
Ser |
0.241 |
|
0.38 |
Val |
0.412 |
Table 4.Ê
Average masses of caffeine extracted from seventy-five milliliters of tea
and seventy-five milliliters of coffee.Ê
The average boiling stone mass was obtained to quantify error.
|
Caffeine
Average in Coffee After Removal of Error Trial (g) |
Caffeine
Average in Coffee For Three Trials (g) |
Caffeine
Average in Tea After Estimated Boiling Stone Error (g) |
Caffeine
Average in Tea For Three Trials (g) |
Boiling
Stone Average (g) |
|
.024 |
.018 |
.011 |
.021 |
.017 |
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