Download Lesson One: The Four Basic Food Molecules

Lesson One: The Four Basic Food Molecules
Reference: Chapter 13, On Food and Cooking by Harold McGee
The four basic food molecules are:
Water
Carbohydrates
Protein
Fats and oils
Water
It has unique properties due to the highly effective formation of hydrogen bonds.
It is ubiquitous.
It is polar and an excellent solvent for salts.
It is a "V" shaped molecule.
It exists in all three states: solid, liquid, gas at ordinary Earth temperatures.
Its solid form floats on its liquid form.
It has a high specific heat.
Hard water has calcium and magnesium ions in it.
The boiling point and freezing point of water can be affected by dissolved substances.
Carbohydrates
The name is a misnomer. It comes from the formula Cn(H2O)n but carbohydrates are not combinations of
carbon and water.
Carbohydrates serve two basic functions: energy and structural
support.
Beta D-Glucose
Energy is stored in sugars, plant starch, and glycogen.
Plant cell walls are strengthened by cellulose and pectic
substances.
Sugars are the simplest carbohydrates. There are many types of
sugar.
Oxidation of sugar reaction:
Sugar + Oxygen => Water + Carbon Dioxide + energy
Sugars participate in hydrogen bonding and have a strong
affinity for water. (sticky)
Starch is the most important polysaccharide for the cook. It is
a chain of glucose molecules.
Amylose: linear chain
Amylopectic: highly branched form (1000s of glucose units)
The more amylose the stronger the gel that will be formed. The more amylopectin the more viscous the solution
that can be made without becoming a gel.
Cellulose
Humans cannot digest cellulose.
Cellulose forms in sheets. You will see this when we build
models.
Proteins
Proteins are made from 20 amino acids that form chains that twist, curl, fold, bend and form many different
shapes. Two important shapes are the alpha helix and the beta pleated sheet.
Proteins are often denatured by heat or acid.
Proteins can coagulate.
Enzymes are a specific type of proteins.
Fats and Oils
The major constituent of natural fats and oils is the triglyceride, a combination of three fatty acids with one
molecule of glycerol.
Fatty acids are long chains of carbon atoms that are terminated with a carboxylic acid group.
Something we all know - fats/oils and water don't mix.
Comparison between fats and gasoline.
The characteristic temperature at which a fat breaks
down into visible gaseous products is called the smoke
point.
As fats oxidize they become rancid.
Triglyceride