Transcript Activity 2.2.1 Food Testing

Activity 2.2.1 Food
Testing
By: Mahi
Introduction
Anna had high amounts of glucose in her blood at the time of her death. Most
likely, she had eaten a large meal before her death. Since glucose levels are
related to the food we consume, exploring Anna’s stomach contents at the time
of her death, may reveal some information of about her meal and provide some
evidence regarding the conditions surrounding her mysterious death. Eating a
balanced diet consisting of; carbohydrates (simple sugars), proteins (crucial to
help build tissue, etc.), and lipids (known as fats). Scientists analyze these
chemical components by using chemical indicators, which is a substance that
changes to indicates the presence of a particular compound or type of
compound. They may change colors or bubble up. In this activity, you will use
chemical indicators to test for compounds in starch, protein, lipids, and sugar.
Equipment needed
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Starch solution, 5% corn starch or other starch soluble in water
Protein solution, 5% albumin in water
Sugar solution, 5% glucose in water
Lipid solution, cooking oil
Anna Garcia simulated stomach contents
Project 2.2.1 Autopsy Report resource sheet
Project 2.2.1 Anna Garcia Food Diary resource sheet
3 small samples of food
200 mL of distilled water in a beaker
8 transfer pipettes
Hot plate with beaker containing distilled water (to make a hot water bath)
12 test tubes
Test tube rack
Test tube holder
Test tube brush
1 beaker, 250 mL
1 beaker, 500mL
Equipment needed continued
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2 stirring rods
Safety goggles
Gloves
Laboratory apron
Laboratory journal
PBS Course File
Benedict’s solution
Lugol’s Iodine stain
Biuret stain
Brown paper, multiple pieces, approximately 2 to 3 cm square
Test #1: Glucose
Benedict’s solution is the indicator used for this process. It turns blue to green
or yellow/orange to red, when simple sugars are present.
To test this process:
1. Put on goggles and make sure the goggles are completely covering your
eyes.
2. Place 1 mL of Benedict’s Solution in two test tubes labeled #1 and #2.
3. Add 1 mL of distilled water to test tube #1. Stir.
4. Add 1 mL of Anna's Stomach Contents to test tube #2. Stir.
5. Using test tube holders,put each of the test tubes in hot water for 3
minutes.
6. Observe and record in your data table the colors of each test tube. If it
turns any color listed above, glucose is present.
Test #2: Starch
Lugol’s Iodine is used as an indicator for starch. If the stomach content being
tested is positive, it will turn dark purple or black.
To test this process:
1. Put on goggles.
2. Place 3 drops of Iodine in two test tubes labeled #1 and #2.
3. Add 1 mL. of distilled water in the test tube labeled #1 and stir.
4. Place a 1 mL. of Anna’s stomach contents in test tube labeled #2.
5. Observe and record the results from both tests. If starch in present in
Anna’s stomach contents, the solution will turn any of the colors listed
above.
Test #3: Protein
Biuret Solution is a protein indicator. If proteins are present, the color changes
to violet or purple. The shade of the color depends on the type and
concentration of the protein. It can range from a light violet to a deep purple.
To test this process:
1. Put on goggles.
2. Put 3 drops of Biuret solution in 2 test tubes that are labeled #1 and #2.
3. Place 1 mL. of distilled water in one test tube and stir.
4. Put 1 mL. of stomach content in the other test tube.
5. Observe and record the results from each test.
Test #4: Lipids
Brown paper will be used to test lipids. If there is an oily film left behind, then
there is lipid present. Fats and lipids leave marks on brown paper.
To test this process:
1. Add 1 or 2 drops of distilled water on a piece of brown paper.
2. Place 1 or 2 drops of stomach content on another area.
3. Let them dry, then record results.
Examples for Glucose test
Example for Starch test
Example for Protein test
Example for Lipid test
Testing food samples
Now, you test three different foods and use the same stomach contents.
Record data and test all foods for all the tests. Summarize information and add
information to Anna’s last meal in the Autopsy Report that goes along with this
activity.
Examples:
Lipid
and
protein
test on
yogurt
Glucose
test
Conclusion
Anna had an unbalanced diet consisting of carbohydrates, proteins, and lipids. Too much sugar in the
body can cause high levels of blood glucose levels. Since carbohydrates basically help create
glucose, eating a lot of it, will cause high levels of glucose. Although, eating a lot of fiber filled foods
can help with digestive system and can slow the absorption of sugar in the body when eaten together
with sugar in the same food. Starches and lipids have the same thing in common; they both are
macronutrients that supply the calories you need for energy. Too much of them, can cause high blood
sugar levels and worsen diabetes. Anna ate very healthy and nutritious food the first day mixed in with
some unhealthy food and on the second day, she had decided to go back to her original eating habits.
Her unbalanced diet can lead to death because it can cause diabetes (which Anna has) which then
can lead to malnutrition, cardiovascular diseases, osteoarthritis, and obesity. They can all kill
someone. Her unbalanced diet could’ve caused her heart arteries to clog and stop pumping blood and
working correctly. In this activity, we learned that food react to certain indicators. This should have also
helped you figure out some more problems that could’ve happened to Anna. In conclusion, the
unbalanced diet and her diabetes may have caused her untimely death.