Lab: Identifying Biological Macromolecules in Food
The purpose of this exercise will be to
i) Identify the macromolecules present in known food samples. ii) Identify the macromolecules present in an unknown food sample and then attempt to identify the origin of that sample. Introduction:
Biochemists have developed standard procedures to determine the presence of the most abundant macromolecules made by cells: carbohydrates (sugars and starches), lipids (fats), and proteins. In this investigation you will conduct some of these standard tests to identify the presence or absence of sugars, starch, lipids and proteins in known samples, in some food samples and then in a food sample of unknown identity.
What biochemical macromolecules are present in different food samples? Can identification of the macromolecules present in a food sample help to identify that sample?
Glassware and Hardware| | |
Safety goggles| 400 – mL beaker| Test tube tongs| Test tubes| Hot plate| Thermometer| Tap water| Depression spot plate| Test tube holder| Test tube stoppers| Tape for marking test tubes| Brown paper towel| |
Testing Solutions in dropper bottles: Lugol’s iodine, Benedict’s solution, Biuret reagent, Sudan IV indicator| | | | |
Standard Samples| | | |
5% glucose solution| 5% starch solution| 5% fructose solution| 5% sucrose solution| Albumin solution| Distilled water| Vegetable oil| Whipping cream| Skim milk| Gelatin solution| | |
| | | |
Food Samples| | | |
Apple juice| Rice “solution”| yogurt with fruit| |
| | | |
| | | |
Unknown Samples| | | |
Could be: chicken broth, potato “juice”, crackers in distilled water, water from squash, or, mashed chickpeas in water.The 3 unknowns actually provided are labelled A, B or C.|
This particular lab investigation does not require a hypothesis.