Sweetness Lab

     In today's lab (9/15/16), we completed a lab, in which it's purpose was to find out how the structure of a carbohydrate affected the taste, in levels of sweetness, of it. My claim of the monosaccharides, disaccharides, and polysaccharides and their degree of sweetness is that the more complex the sugars are, the less sweet they are. I noticed the smaller particles, the monosaccharides, tasted much more sweet than other, much more larger polysaccharides. I rated fructose and glucose, as well as sucrose 140, 80, and 100 respectively. I found the fact that sucrose was also very sweet, even though it was a disaccharide. I believe that this is because glucose is created after the process of digestion, and not naturally obtainable, so the body does not interpret it as a sugar. Sucrose, however, also has the sugar fructose, which is much higher in sweetness than any of the other sugars we tested. My reasoning was that the smaller sugars like the monosaccharides and disaccharides could easily fit into the binding site of the heterodimer of two G-protein coupled receptors, T1R2 and T1R3, in charge of sending messages through the nervous system to tell the brain how to interpret how the food tasted. The larger sugars, like starch or cellulose, simply didn't fit into the binding sites of these receptors. This is supported by my observations in this lab, that the smaller sugars like fructose tasted much more sweeter than anything else, while polysaccharides like starch and cellulose were tasteless.

Results of our lab

     I think the carbohydrate structure affects how they are used in cells, as simple sugars like glucose are quickly metabolized. Things like fructose, which is metabolized by the liver, gives a huge energy boost for a very short amount of time. Things like starch or other polysaccharides have a lot more energy in them, and take a lot of time for the enzymes in our body to break the bonds between the sugar rings. This results in a slow, lasting energy release, which results in a lot more energy over the course of hours, whereas simple sugars are consumed in matters of minutes.
     Each testers gave each sample about the same amount of sweetness, relative to the standard 100 sweetness of sucrose. However, there were a few disagreements. Some felt that the sweetness was lower than what I felt was the sweetness level, and some felt that there were different tastes other than sweetness in some of the less sweet polysaccharides or disaccharides like starch or lactose. They thought, along with being bland, they was bitter and dry, whereas all I tasted was nothingness. The first reason I think this is that some have been accustomed to other food. I eat quite a lot of spicy and sweet food, so I'm accustomed to a lot of flavor. Small amounts of bitterness or dryness just don't trigger my trigeminal nerve to register the flavor. Another reason is that I felt some of the other testers might accustomed to eating high sugar levels at a time, so they didn't taste the low level of sugar from things like maltose or galactose. The third reason is that once someone had put their finger on the sample, some of the finger's salt, oil, and bits of the previous sample went onto the current sample, so the next tasters could've thought that the sample tasted less or more sweetness that the actual sample was.
     Humans have receptors on our tongues that detect the chemical substances that have been broken down by enzymes in the saliva in our mouths. These chemical substances then change the proteins in the walls of sensory cells on our tongues. In turn, the sensory cells transfer messenger proteins, which then submits the information to our nervous system, which then passes the interpreted flavor to the brain, where it identifies the taste as either of the five basic tastes: sweet, sour, savory, salty, or bitter. This information is coupled with scent of the food, as information sent from the nose, in order to truly identify the taste of food.

Picture of our Sweetness Lab Setup