The foods that we eat everyday have nutritional value that our body needs in order to
function to its fullest capacity.
Four macromolecules that are found in our diet are:
carbohydrates, starches, lipids and proteins.
These macromolecules can be found in an array of
different foods, whether they are naturally or artificially synthesized.
Carbohydrates are composed of hydrogen, carbon and oxygen and can be classified into
two categories: monosaccharides (simple sugars) and polysaccharides (two or more
They are also the preferred macromolecule for obtaining energy (ATP) by
cells within the body; minimal energy is required for the breakdown of carbohydrates.
Carbohydrate monosaccharides are found in foods, in the form of glucose and fructose.
polysaccharide consists of two or more monosaccharides and an example would be a starch.
Starch is found in plants, acting as an energy storage facilitator (Campbell, et al., 2008).
Lipids have numerous functions, one of which is the most efficient use of lipids in the
form of energy storage: triglycerides.
Triglycerides are composed of a glycerol backbone and
three fatty acid chains, and an ester bond.
Lipids are hydrophobic, meaning that they are not able
to break down in water, which can have its advantage in the human body, which can hold large
amounts of water.
When the body does not have carbohydrates to use for energy, its next best
choice is lipids. Because lipids are hydrophobic it requires a lot more work to break them down
(Campbell, et al., 2008).
Finally, the last macromolecule to be mentioned is protein.
They are the most
complicated compounds found in nature.
Proteins are composed of carbon, hydrogen and
oxygen just like everything else, but it also contains another key element: nitrogen.
long chains of amino acids.
They are also polar, meaning they are soluble in water, but not all
So when we consume foods that contain proteins, they are broken down to
their smallest form: amino acids.
The body then uses the amino acids in order to build proteins.
They help compose enzymes, blood cells, and muscle tissues (Couch and Berger, 2004).
There are four tests that can be done on any given food to test whether they are
carbohydrates, starches, lipids or proteins; those tests are Benedict’s test, Starch test, Sudan IV
test and the Biuret test.
Benedict’s test is used for the detection of sugars; if there proves to be
sugars the solution will become “cloudy” and have a yellow-orange color.
The starch test uses
iodine, which inserts itself within monosaccharide chains of starch molecules, which causes a
deep blue-black color.
The Sudan IV test is a dye that is soluble in lipids but not in water.
dye stains the fatty acid molecule red-orange.
The Biuret test is used for the detection of
Each tested material is then given 1mL of Biuret reagent, which is then shaken and if