Question

The fructose in honey is mainly in the β-D-pyranose form. This is one of the sweetest carbohydrates known, about twice as sweet as glucose. The β-D-furanose form of fructose is much less sweet. The sweetness of honey gradually decreases at high temperature. Also, highfructose corn syrup (a commercial product in which much of the glucose in corn syrup is converted to fructose) is used for sweetening cold but not hot drinks. What chemical property of fructose could account for both observations?

Answer 1

The chemical property of fructose that accounts for both observations is its instability at high temperatures. When heated, the sweeter β-D-pyranose form of fructose in honey can convert to the less sweet β-D-furanose form, causing a decrease in sweetness. Similarly, high-fructose corn syrup is used for sweetening cold drinks due to the potential conversion of fructose from the β-D-pyranose to the less sweet β-D-furanose form when heated.

Step-by-step explanation:

The chemical property of fructose that could account for both observations is its instability at high temperatures. Fructose in the β-D-pyranose form is more stable and sweeter, while the β-D-furanose form is less stable and less sweet. When honey is heated at high temperatures, the β-D-pyranose form of fructose can convert to the less sweet β-D-furanose form, causing a decrease in sweetness. Similarly, high-fructose corn syrup, which is mainly composed of fructose, is used for sweetening cold drinks because heating it may lead to the conversion of β-D-pyranose fructose to the less sweet β-D-furanose form.

Answer 2

Answer: increase in temperature decreases the sweetness of fructose

Explanation: this is because beta- fructose will undergo cyclization from its straight chain to give furanose and pyranose. Increase in temperature will just favors the yielding of more of furanose which is less sweet. Which is why it is used to sweetened cold drinks to maintain the sweetness as hot drinks is just going to reduce it.