Chemists have been looking for a sweetener that is sweet or sweeter than sucrose. They want it to have a pleasant taste with no aftertaste, is nontoxic, inexpensive, easy to make, stable to heat, stable in light, dissolves
Readily in water, does not promote dental cavities, and preferably has no caloric content. Sweetness is not a simple property to work with. There are a lot of other properties that scientist has studied to get that right sweet taste. There is something that they all have in common and that’s the “TRIANGLE THEORY”.
This theory is a sweetener molecule or “glucophore” that has three key sites arranged at the corners of an imaginary triangle and these sites give the molecule the ability to lock onto receptor sites in our taste buds where the sweet taste triggers a response in our brains. The receptors in our taste buds are composed of proteins, and these have the ability to form hydrogen bonds with other molecules.
Proteins have (1) N-H and O-H groups that can supply the H in a hydrogen bond and (2) C=O groups that can be the acceptor in the hydrogen bond. The triangle theory states that one site in a sweet molecule must act as the H-atom donor in a hydrogen bond (SITE A).
Throughout biochemistry there are many bonds without which life as it is on earth today would not be possible. One of the most important bonds of these is the hydrogen bond, a weak chemical bond that is present in essential biological molecules such as water and polypeptides. A hydrogen bond is defined by Campbell and Reece as occurring when a hydrogen atom is covalently bonded to an ...
A second site, about 300 pm away from the first site, is an acceptor Atom for hydrogen bond (site B).
The third site, the third corner of the triangle, has no hydrogen bonding capacity but is a hydrophobic site.
This corner can be an N-H or and O-H group it can form a hydrogen bond with an O or N atoms in the receptor in the taste bud. Site A in the Triangle Theory is the electronegative atom to which the H is bonded, Site B’s corner is an electronegative atom with a lone pair of electrons that can form hydrogen bonds with N-H or O-H groups in the taste receptors, Site C is the group that repels water. Here is what the model of the “Triangle Theory” looks like.