Chemical introduction of fructose

The raw material for large-scale industrial production of fructose is sucrose, which can be hydrolyzed by dilute hydrochloric acid or invertase, and the product is a mixed solution of fructose and glucose. Adding calcium hydroxide makes fructose and calcium hydroxide form insoluble compounds, which are filtered and separated from the aqueous solution. Then carbon dioxide gas is introduced, so that calcium hydroxide reacts with carbon dioxide to generate calcium carbonate with little solubility, and then the calcium carbonate is filtered out and the water is evaporated to obtain fructose crystals.

Another method to produce fructose is to hydrolyze starch into sugar by immobilized glucose isomerase, which contains 42% fructose and 58% glucose. This mixture is called high fructose syrup or high fructose syrup.

Fructose is a prismatic crystal with a melting point of 103 ~ 105℃, which is the sweetest of all sugars. The sweetness is twice that of sucrose, which is widely distributed in plants and widely used in food industry, such as making candy, cakes, drinks and so on. The sweetness of high fructose corn syrup is equivalent to that of sucrose, but it is produced from starch, which is not only low in cost, but also has the fragrance of natural honey, and is more widely used than sucrose in food industry.

Also known as levo-sugar. It is a monosaccharide, the full name is D- arabinose, and the molecular formula is C5H 12O5CO. Fructose exists in free form in fruit juice and honey, and it is the only reducing sugar in bovine and human semen. D- fructose stores energy in Jerusalem artichoke (the root of Dahlia) in the form of polysaccharide. A large amount of sucrose exists in the form of glycosidic bond connected with D- glucose. In the crystalline state, there may be β -pyranose in ketose, which is often combined with furanose in natural products. Furofuranose and pyranose coexist in aqueous solution, and there is about 20% of furofuranose in aqueous solution at 20℃.

Glycosides formed by fructose are rare in nature. Fructose is a prismatic crystal with melting point 103 ~ 105℃ (decomposition). Fructose is the sweetest of all sugars, about twice as much as sucrose, and can be obtained by hydrolyzing Jerusalem artichoke. Sucrose is the most abundant raw material for large-scale industrial production of fructose. Sucrose is hydrolyzed by dilute acid or invertase, and fructose is separated from the solution mixed with D- glucose. Fructose is not easy to crystallize, but it forms an insoluble complex with calcium hydroxide. After separation, fructose crystals can be obtained by introducing carbon dioxide. In industry, bromine water can also be used to selectively oxidize glucose in sucrose hydrolysate, and then remove D- gluconic acid to obtain fructose. Objective large-scale industrial production use starch hydrolysis to prepare glucose, which is converted into invert sugar by immobilized glucose isomerase, in which fructose content is 42% and glucose content is 58%. It is commercially called high fructose syrup or high fructose syrup. Its sweetness is equivalent to that of sucrose, but it has the characteristics of natural honey fragrance and low production cost, and has been widely used in food industries such as beverages, sweets and cakes.

One of C6H 12O6 ketone monosaccharides. White crystal or powder, the goods are often light brown and sweet. The density is 1.6g/cm3, and the melting point is 103 ~ 105℃ (decomposition). Soluble in water, ethanol and ether. The active ketone group without aldehyde group can produce silver mirror reaction, and the oxidation products are glycolic acid and trihydroxybutyric acid. Calcium fructose precipitate can be formed by lime water, but fructose can be recovered by introducing carbon dioxide. Used as food, nutrient and preservative. Stored in fruits and honey. It is usually prepared by hydrolysis of inulin.

Silver mirror reaction of fructose

Glucose and fructose are isomers of each other. Glucose is a polyhydroxy aldehyde (aldose) and fructose is a polyhydroxy ketone (ketose). Fructose has no aldol group in its molecule, so it seems that the silver mirror reaction cannot occur, but it is not. The main reason is that fructose can react in alkaline solution in two ways: one is to become aldose through enolization (the reaction equation is abbreviated). The second is cracking to produce organic compounds containing aldehyde groups (the chemical equation is abbreviated). 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. Therefore, fructose solution always contains aldose and organic compounds containing aldehyde groups, which can react with alkaline silver ammonia solution through silver mirror. Therefore, fructose and glucose are both reducing sugars. The silver mirror reaction effect with fructose is similar to that with glucose. The reaction conditions are slightly higher than that of glucose. At 60- 100℃, the mass fraction of fructose solute is 1%, and the mass fraction of silver nitrate solution and ammonia water solute is 2-4%. Under these conditions, high quality silver mirrors can be obtained.

Note: the reducibility of fructose was not mentioned in the chemistry textbook of senior high school before, and the biology textbook showed that fructose could react with Feyning reagent when testing reducing sugar. Scientific inquiry has been added to senior high school chemistry textbooks, allowing students to explore this problem independently. Drying method of 1. 1, 6- fructose diphosphate

2. Method for producing1,6- fructose diphosphate

3. purification method of1,6- fructose diphosphate

Biosynthesis of 4. 1.6- fructose diphosphate

5. A preparation method of fructooligosaccharides

6. Preparation method of starch hydrolysate and high fructose corn syrup

7. Drying method of lactulose solution

8. Preparation method of high-purity fructooligosaccharides

9. Method for producing high-fructose syrup by hydrolyzing inulin with immobilized inulinase.

10. Separation of fructose by immobilized boric acid (I) Principle: Fructose is a typical reducing sugar containing reducing groups (free ketone groups).

Methods: 1. Fructose+Fehling reagent/Bancroft reagent → brick red precipitation.

2. Fructose+silver ammonia solution (alkaline environment, water bath heating) → silver mirror reaction

(2) UV spectrophotometry

(3) High performance liquid chromatography

(4) ion selective electrode method

(5) Fourier transform near infrared spectrum

(6) Spectrophotometry