Sweetness is a complex physical, chemical, and physiological process produced by sweetener molecules stimulating taste buds. The degree of sweetness is called sweetness level, an important indicator of sweetener quality. Sweetness level cannot be quantitatively measured using physical or chemical methods; it can only be judged by human sensory perception. To compare the sweetness levels of sweeteners, sucrose is generally chosen as a standard, and the sweetness of other sweeteners is determined by comparison to it, resulting in a relative sweetness level. There are two methods for determining relative sweetness: one is to prepare the sweetener to the lowest concentration at which sweetness can be perceived, called the limiting concentration method; the other is to prepare a solution of the sweetener with the same concentration as sucrose, and then compare the sweetness of the sweetener with the sucrose solution as a standard, called the relative sweetness method.
Relative Sweetness of Various Sweeteners
The sweetness level of sweeteners is affected by many factors, the main ones being concentration, temperature, and medium.
Generally speaking, the higher the concentration of the sweetener, the greater the sweetness. However, the degree to which the sweetness of most sweeteners increases with concentration is not uniform.
The sweetness of most sweeteners is affected by temperature, generally decreasing as temperature increases. For example, a 5% fructose solution has a sweetness of 147 at 5°C, 128.5 at 18°C, 100 at 40°C, and 79.5 at 60°C.
The medium also has an effect. In aqueous solutions below 40°C, fructose is sweeter than sucrose, while in lemon juice, their sweetness is roughly the same.
