Basic Information
Chemical Name and Structure
Crystalline Fructose, chemically named D - Fructose, is a monosaccharide. Its molecular formula is , and it is an isomer of glucose. The structure of fructose is a polyhydroxy ketone, with five hydroxyl groups (-OH) and a ketone group (C = O) in the molecule. Its cyclic structure mainly exists in the forms of furanose and pyranose, and the two cyclic structures can be interconverted in solution. These structural characteristics determine many of its physical and chemical properties, such as sweet - tasting characteristics and solubility.
Appearance and Properties
Crystalline fructose is usually colorless crystals or white crystalline powder, odorless, and sweet - tasting. The crystal grains are relatively uniform in size and have good fluidity. In powder form, it has a fine texture and is not prone to caking during storage, which gives it good operability in applications such as food processing.
Physical and Chemical Properties
Solubility
Crystalline fructose has good water - solubility, and its solubility in water increases with rising temperature. At 20ºC, the solubility is approximately 375g/L, and at 30ºC, the solubility can reach about 440g/L. It can also be dissolved in ethanol and methanol, but has a lower solubility in non - polar organic solvents (such as ether and benzene). These solubility characteristics enable it to function in a variety of solvent systems and are widely used especially in aqueous food and beverage systems.
Sweetness
Fructose is the sweetest among natural sugars, and its sweetness is about 1.2 - 1.8 times that of sucrose. This high - sweetness characteristic enables the use of a smaller amount in the food and beverage industry to achieve the same sweetness effect as a larger amount of sucrose, helping to reduce the caloric content of products and also providing the possibility of developing low - sugar and high - sweetness products.
Hygroscopicity
Crystalline fructose has a certain degree of hygroscopicity. In an environment with relatively high humidity, it will absorb moisture from the air. However, compared with other sugars (such as glucose), its hygroscopicity is relatively weak. In an environment with well - controlled humidity, it can maintain a good crystalline state and stability.
Chemical Stability
Under acidic conditions, fructose is relatively stable. However, under alkaline conditions, fructose is prone to isomerization reactions, generating other sugars such as glucose and mannose. During the heating process, especially under the combined action of high temperature and alkaline environment, decomposition reactions will occur, producing substances such as caramel, and the color will gradually become darker.
Quality Standards and Specifications
Purity Standard
For crystalline fructose products, purity is a key quality indicator. Generally, the purity of industrial - grade crystalline fructose is required to be above 95%, and the purity of food - grade fructose is even higher, usually above 99%, to ensure the quality and safety of the product, as well as its stability and effectiveness in applications such as food.
Impurity Limitations
Moisture Content: The moisture content is generally required to be controlled below 0.5%. Excessive moisture will affect the crystalline state, shelf life, and performance of crystalline fructose.
Heavy Metal Content: There are strict limitations on the content of heavy metals (such as lead, mercury, arsenic, etc.). For example, the lead content is usually not more than 0.5mg/kg, the mercury content is usually not more than 0.1mg/kg, and the arsenic content is usually not more than 0.5mg/kg to ensure that the product meets food safety standards.
Other Sugar Impurities: The contents of other sugar impurities such as glucose and sucrose also need to be strictly controlled, because they may affect the sweetness, solubility, and other properties of crystalline fructose. Moreover, in some application scenarios (such as the medical field with extremely high purity requirements), these impurities may have adverse effects.
Uses and Application Fields
Food Industry
Crystalline fructose is an ideal sweetener and is widely used in beverages (such as fruit juice beverages, carbonated beverages, sports beverages, etc.). It can provide a refreshing sweet taste, and due to its high - sweetness characteristic, it can reduce the caloric content of products while maintaining a good taste. In baked goods (such as bread and cake), it can participate in the Maillard reaction, forming an attractive color on the product surface and improving the flavor and texture of the product. In candies, jellies, and other products, its high - sweetness and good solubility can make the products more delicious.
Medical Field
In the medical field, crystalline fructose can be used as a sweetener for drugs to improve the taste of drugs. Especially for some drugs with a bitter taste, adding crystalline fructose can improve patient compliance. At the same time, because the metabolic pathway of fructose in the body is different from that of glucose, it can be used as an energy supplement for patients with certain special diseases (such as diabetes), providing energy without causing a sharp increase in blood sugar.
Cosmetics Industry
In the cosmetics field, crystalline fructose can be used as a moisturizer and added to skin - care products (such as creams and lotions). It can absorb and retain moisture in the skin, keeping the skin hydrated. In addition, its sweet - tasting characteristic can also add a pleasant flavor to some lip products with edible ingredients (such as lip balms and lip glosses).
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