Fructose is a monosaccharide and an isomer of glucose. Fructose exists in a large number of juice and honey sold by bees in a free state, and it can also combine with glucose to produce sucrose. Glucose and fructose are isomers of each other. Glucose is a polyhydroxy aldehyde (aldose) and fructose is a polyhydroxy ketone (ketone makes sugar funny). There is no aldol group in fructose molecule, so it seems that silver mirror reaction cannot occur.
But in fact, this is not the case. The main reason is that fructose can react in alkaline solution in two ways: first, it becomes aldose through enolization. Second, cracking occurs to produce organic compounds containing aldehyde groups. Due to the influence of multiple hydroxyl groups in fructose molecules on ketone groups, fructose can also undergo silver mirror reaction and be oxidized by newly prepared Cu(OH)2.
Characteristics of fructose:
Fructose also has good hygroscopicity. Fructose has the strongest hygroscopicity and can easily absorb water in sugar-watching plants. The good hygroscopicity of fructose makes it suitable for the processing of bread, cake, candy and other foods that need moisturizing. The application of fructose in candy can prevent crystallization and sand return, especially for high-grade candy and chocolate. Because of its hygroscopicity, fructose can also be used as a humectant for cosmetics and tobacco.
The use of fructose in the marking points of bread and cake can make the cake soft in texture, long in drying time and excellent in fresh-keeping performance, which can obviously improve the product grade and prolong the shelf life. In addition, fructose is a monosaccharide, which is easy to be used by yeast and has a fast fermentation speed. Fructose is easy to decompose when heated, and it is easy to coking with amino acids. Therefore, when it is applied to baked goods (such as bread), it can not only achieve a soft and delicious effect, but also increase the surface Huang Liang color and rich burnt flavor.