* Testing for Macromolecules
* September 20, 2012 – September 25, 2012
* Rebekah Alto, Chayene Banta, Taylor Denton, Sarosh, Brianna Madar * Mrs. Kolobaric
To use a set of standardized procedures to test for simple sugars and starch, proteins, and fats.
-Safety goggles -Lab apron -400 mL beaker -Utility stand with ring clamp-Hot plate -Thermometer -10 mL graduated cylinder-Test-tube racks -8 to 16 test tubes -Test tube holder-Medicine dropper -Rubber stoppers -Test-tube brush-Wax pencil -Distilled water
-Depression spot plate -Baking soda solution,5% -Glucose solution, 5% -Known foods; glucose, corn starch-Cornstarch suspension,5% -Detergent solution -Unknown food samples-Benedict’s reagent -Lugol’s solution -Sudan IV indicator-Unglazed brown paper -Gelatine solution, 5% -Biuret reagent
1. Safety goggles and lab apron were put on.
Part A: Carbohydrate Test
2. Poured 300 mL of water into a 400 mL beaker. Secured the beaker with a ring clamp, placed it on a hot plate, and heated the water to 80 °C.
3. Used a 10 mL graduated cylinder and measured 3 mL of the following: distilled water, baking soda solution, glucose solution, starch solution, bananas, eggs, and oats. Poured each solution into a new, clean test tube.
4. 1 mL of Benedict’s reagent was added to each test tube.
5. Used test tube holder to transfer the test tubes into the hot water bath. Colour changes were recorded after 6 minutes of observations.
6. Placed a drop of distilled water and a drop of Lugol’s solution on a depression spot plate with medicine dropper. Recorded colour of solution.
7. Repeated step 6, but placed a drop of each solution into the spot plate. Recorded the observations and indicated which solutions were positive for the presence starch.
Part B: Lipid Test
8. Measured 3 mL of the following: distilled water, baking soda solution, vegetable oil, gelatin, butter, and egg. Poured each into a clean, labelled test tube.
9. 6 drops of Sudan IV indicator were added to each test tube. Placed a rubber stopper in each test tube and shook vigorously for 2 minutes.
10. Recorded the colour of each mixture.
11. Drew and labelled a circle on a piece of unglazed brown paper for each sample to be tested.
12. A drop of each sample from step 8 was placed into its appropriately labelled circle.
13. Compared the distilled water sample to each of the other samples by holding them up to the light after the water was evaporated from each circle. Recorded whether the samples were translucent or not in the data chart.
Part C: Protein Test
14. 2 mL of water, baking soda, gelatin solution, banana, oats, egg, and butter were put into clean, labelled test tubes.
15. Added 2 mL of Biuret reagent to each test tube and tapped the test tube with fingers. Colour changes were recorded.
Part A: Carbohydrates
Solution| Colour/ Approx. sugar concentration| Positive for Starch| Distilled water| Blue / 0| ✘|
Baking soda solution| Blue / 0| ✘|
Glucose solution| Orange / 1.5-2.0| ✘|
Starch solution| Brown / > 2.0| ✔|
Banana solution| Brown / > 2.0| ✘|
Oat solution| Brown / > 2.0| ✘|
Egg solution| Brown / > 2.0| ✔|
Part B: Lipids
Solution| Colour Change| Translucent?|
Oil| Red| ✔|
Egg| Red| ✘ (Fell off / Error)|
Gelatin| Pink| ✔|
Butter| Red| ✔|
Starch| Red| ✔|
Glucose| Pink| ✘|
Detergent| Pink| ✘|
Oats and Banana| Red| ✘ (Fell off / Error)|
Baking soda| Pink| ✘|
Water| Pink| ✘|
Part C: Proteins
Solution| Colour Change| Comments|
Water| Blue| No protein|