Sweetness Lab

In this lab, we tasted different types of carbohydrates and rated their sweetness. The purpose of this lab was to find out how the structure of a carbohydrate affects its sweetness. Based on my observations, monosaccharaides are the sweetest type of carbohydrate, followed by disaccharides, and finally polysaccharides.  In the lab, we rated the sweetness of the sugar on a scale of 1-200, 1 being no sweetness at all, and 200 being the sweetest thing you have ever tasted. The monosaccarides glucose, fructose, and galactose had scores of 120, 180, and 70. The disaccharides sucrose, maltose, and lactose scored 100, 40, and 20. Finally, the polysaccharides starch and cellulose scored 10 and 1. The monosaccharides had the highest score, followed by disaccharides and polysaccharides. This evidence supports the claim because the taste receptors on the tongue can detect sweetness better than almost everything. 

Carbohydrate	Type of Carbohydrate	Degree of Sweetness (1-200)	Color	Texture	Other Observations/Connections to food
Sucrose	disaccharide	100	white	granular	It is like table sugar
Glucose	monosaccharide	120	clear white	powdery	Found in bread
Fructose	monosaccharide	180	white	granular	Found in frosting
Galactose	monosaccharide	70	white	powdery	Looks like powdered sugar
Maltose	disaccharide	40	brown	powdery	Found in beer
Lactose	disaccharide	20	white	powdery	Found in milk
Starch	polysaccharide	10	white	granular	Found in bread
Cellulose	polysaccharide	1	white	powdery	Found in plant cell walls

A picture of the different types of sugars that I tasted

The structure of carbohydrates might affect how they are used by cells/organisms. The amount of energy in a carbohydrate depends on the amount of bonds it has. Cells might use polysaccharides first because they have the most energy. Only when there are no polysaccharides then will the cell resort to disaccharides and monosaccharides.

Not all the testers gave the same rating. We all have a different amount of taste receptors dedicated to sweetness. As a result, we perceive sweetness differently. Another possibility is that the taster forgot to drink water, so their taste would be dependent on what they had tasted before. The last reason is that someone could have had a cold. When you have a cold, most things taste more bland than they normally do. This results in skewed ratings. 

Humans taste sweetness through receptor proteins, commonly known as taste receptors. Once something sweet touches the receptor cell for sweetness, that cell will send a message to the brain. It is like a lock and key. The sweet object "key" has a chemical reaction with the receptor cell "lock" that causes it to send a message to the brain. Tasters could rank sweetness differently because people have higher or lower abilities to taste food. People who are supertasters detect more sugar than normal people, and people with lower abilities detect less sugar than normal people.