Organic Substance Lab Assignment Instruction: WatchOrganic substances in food lab (Links to an external site.)(mark 6:08 to end 13:14) for testing food samples. Follow procedure above and record observations in Table 3 below.
| Table 3. Observed color changes and stain pattern indicating presence or absence of organic substance in food samples | ||||||
| Reagents/Organics Food sample | Benedict’s (final color) | Iodine (final color) | Ninhydrin (final color) | Glucose sugar (+ or -) | Starch (+ or -) | Protein (+ or -) |
| Potato | ||||||
| Cabbage | ||||||
| Apple | ||||||
| Almond | ||||||
| Bread | ||||||
| Potato chips | ||||||
| Ground beef | ||||||
| Ham | ||||||
| Hotdog |
Organic Substance Lab Part 2: Test for Lipids (DIY)
Materials
For lipid test: (Note if your group does not have these materials, please inform instructor)
- Brown paper (ie. paper bag or envelope)
- Water
- Oil
- Salt water (a pinch of table salt dissolved in ~1 Tablespooon of water)
- Sugar water (a pinch of sugar dissolved in ~1 Tablespooon of water)
- Two or more of the following:
- Preferred substances: any item in Table #3 above.
- Other liquids: for example, milk, juice, soda, salad dressing, vinegar, ketchup, mustard
Organic Substance Lab Procedure
Testing the reagents
To demonstrate this process for lipids, you will use the reagent of brown paper. From this test, you will be able to determine if the substance has lipids.
Lipid test: You can perform this test on your own. You will need brown paper, such as a paper bag or envelope. Note that brown paper readily absorbs lipids. Please follow this procedure:
- Cut a piece of brown paper approximately 8.5 x 11 inches.
- Draw approximately 6 circles with ~1 inch diameter. Each circle should be spaced ~2 inches apart.
- Label one circle “water” and place one drop of water in it.
- Label one circle “oil” and place a drop of oil in it.
- Observe each circle at time 0 immediately after you placed the drop. Does the paper stain look clear, even (uniform) or uneven? Record in table below the results.
- Observe each circle after 15 minutes. Turn the paper over. Does the paper stain look clear, even (uniform) or uneven? Record in table 4 below the results.
Table 4. Brown Paper Test for Lipids | |||
| Reagent/ Substance | Brown Paper (stain appearance at 0 min: clear, uneven or even) | Brown Paper (stain appearance at 15 min: clear, uneven or even) | Lipid (fat) (+ or -) |
| water | |||
| oil | |||
| sugar water |
Note: Any paper with a uniformly wet-looking stain contains fat. Any paper that is relatively clear or unevenly stained does not contain fat. Organic Substance Lab
Interpret the previous table, determine the appropriate stain pattern and fill in the table below.
| Table 5. Reagent Test for Organic Substances (continued) | ||
| Organic substance | Reagent | Expected color change |
| Lipid (fat) | brown paper |
Testing for the presence of lipid (fat):
- Gather your other substances: liquids or solids with moisture (ie. milk, salad dressing, juice, soda, potato chips, etc).
- On your brown paper, place one drop of liquid in its circle or smash a piece of solid and place in circle.
- After 15 minutes, flip paper over to view and record the appearance of the stains in Table #4. Stain can be clear, uneven or even. Recall that any paper with a uniformly wet-looking contains fat similar to the oil. Any paper that is relatively clear or unevenly stained does not contain fat similar to the water.
Results
| Table 6. Observed color changes and stain pattern indicating presence or absence of organic substance (lipid) in food samples | ||
| Reagents/ Organics Food sample | Brown Paper (final stain) | Lipids (+ or -) |
Organic Substance Lab Discussion/Conclusion
- Name example(s) for each item below and which organic substances are found in them.
| Table 5. Different Types of Food Samples and Organic Substance Content | ||
| Type of food sample | Food samples | Organic substance(s) present |
| unprocessed animal samples | ||
| unprocessed plant samples | ||
| processed food samples from animals | ||
| processed food samples from plants |
- Compare and contrast organic substances found in plants versus animals.
- Compare and contrast organic substances found in unprocessed versus processed foods.
- Which types of food should be avoided by an overnourished (obese) person? Briefly justify your answer.
- Which types of food should be eaten by a person who wants to build up his/her muscles? Briefly justify your answer.
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