English Views: 0 Author: Site Editor Publish Time: 2023-05-06 Origin: Site
Inulin is a polysaccharide of plants, which is mainly composed of fructose. The most well-known plant polysaccharide is starch, so some people call inulin with similar functions as inulin. Inulin will not be digested and absorbed by the human body, and has water retention properties. When dissolved in water, it will form a viscous jelly-like substance, so it is a kind of water-soluble fiber. Inulin is classified as a general safe food raw material by the US Food and Drug Administration (FDA). Substances that allow intestinal probiotics to multiply).
Inulin is a fructan formed by connecting D-fructofuranose molecules with β-(2,1) glycosidic bonds and a glucose residue at the end with α-(1,2) glycosidic bonds. Its degree of polymerization (degree of polymerization, DP) is usually 2 to 60, the average degree of polymerization is 10, and the average molecular weight is about 5 500 U. The degree of polymerization and average molecular weight of inulin are related to the source of inulin, harvest season, and processing methods.
Inulin is a straight-chain polysaccharide whose backbone is polyethylene oxide without any sugar rings. Compared with other sugars, there is only one oxygen atom between the fructose sugar rings in the inulin molecule, and the fructofuranose is in the same plane, so the inulin molecule has a greater degree of freedom of movement and is easier to flip and curl, so The molecular structure of inulin has variable properties. Studies have found that the molecular structure of inulin is closely related to its degree of polymerization, especially the structure of inulin molecules with DP<9 and DP≥9 is significantly different. The molecular structure of inulin with DP 4 and 5 forms a ring structure [7] and a single helical structure due to flipping and coiling; the inulin molecules with DP6-8 are not yet conclusive, but their spectral characteristics are different from those with DP 4 and 5. Therefore, it can be deduced that the molecular arrangement of inulin molecules has changed; while the inulin molecules with DP≥9 present regular helical structures-pentupt helix and hexafold helix. The molecular structure of inulin changed with the increase of DP, so DP would affect the processing properties of inulin.
1. Hydrophilic properties
Inulin molecules contain a large number of hydroxyl groups and have good hydrophilicity, but their solubility is limited by the chain length. After inulin dissolves in water, hydrogen bonds are formed within the inulin molecule, between inulin molecules, and between inulin and water molecules, and are connected to each other to form a three-dimensional network structure; while part of inulin that is not soluble in water will It exists in the form of crystalline inulin, and crystalline inulin will form hydrogen bonds between molecules to connect inulin molecular chains to chains, which can strengthen the network structure of inulin and form a gel network structure containing crystalline particles.
(1) Inulin can be used as a thickener
The report found that the viscosity of inulin solution is closely related to temperature, concentration, and DP. In practical applications, the ingredients of food also have a great influence on viscosity. Long-chain inulin can significantly increase the viscosity of the solution at a lower temperature and concentration, and this property is often used in food as a food thickener.
(2) Inulin can be used as a fat substitute
Since inulin DP affects the molecular structure of inulin, the long-chain inulin exhibits a multiple helical structure, thus forming a stronger gel. The higher the DP, the lower the concentration of inulin needed to form the gel, and the gel structure formed by the long-chain inulin with DP 22-23 is stronger. In food, the gel properties of inulin are often used as a fat substitute in low-fat foods. However, inulin is not limited to forming gels with water in practical applications. The matrix of food has an important influence on the formation of gels. For example, adding 6% long-chain inulin to low-fat yogurt can form secondary The gel structure gives the yogurt a full-fat taste.
(3) Inulin can be used as a water retaining agent
In the inulin aqueous solution, the three-dimensional network structure formed between inulin and water molecules can capture a large number of water molecules, and the water molecules are wrapped in the middle of the inulin molecules to form gel particles. Gel particles are not easy to be damaged by the environment, and water molecules are not easy to lose. Therefore, inulin has good water holding capacity and moisture retention. In the process of food processing, it can effectively reduce water loss and can be used as a water-retaining agent.
2. Has hydrolytic properties and can be used as a sweetener
The viscosity of low concentration inulin solution does not change much, and it is not easy to form a gel state. Inulin molecules are dispersed in water, and the terminal fructosyl groups are easily broken to produce fructose molecules. Studies have found that inulin can increase the sweetness of sucrose by 35%, so it can partially replace the sweet taste of sucrose.
3. Prebiotic properties
Short-chain inulin is easily hydrolyzed to produce fructose molecules, which can be used as a carbon source by most microorganisms; in addition, some microorganisms contain inulinase, which can degrade inulin into monosaccharides and disaccharides for utilization, so Inulin can promote the growth of microorganisms. Studies have shown that adding inulin to low-fat yogurt is beneficial to the growth and fermentation of beneficial bacteria such as Streptococcus thermophilus, Lactobacillus bulgaricus, Lactobacillus acidophilus, and Lactobacillus rhamnosus, and can effectively improve the storage period of yogurt. The number of live bacteria.
With the improvement of living standards, the obesity rate is getting higher and higher. In order to prevent obesity, more people prefer to choose low-fat, low-sugar, and fiber-rich foods. Inulin is not only a water-soluble dietary fiber, but also has unique processing characteristics, which can effectively improve the sensory and texture of low-fat foods, so it is often used in foods such as dairy products, meat products, flour products, chocolate and ice cream Processing.
1. Dairy products
Due to the lack of fat, skimmed or low-fat dairy products are prone to adverse phenomena such as bland taste and whey precipitation. Adding inulin to dairy products can improve its texture, increase viscosity and water holding capacity, and provide a smooth taste similar to fat; it can promote the growth of microorganisms in fermented dairy products.
2. Meat products
The addition of inulin can partially replace the fat in meat products, and obtain a taste similar to that of full-fat meat products, but it will lead to darker meat products, increased hardness, and texture changes.
3. Flour products
(1) Baked noodle products
Bakery flour products mainly include bread, cakes and biscuits. The addition of inulin with different degrees of polymerization can improve bakery products in different ways, but all of them will increase the hardness of the product and deepen the color of the product.
(2) Cooked noodle products
Steamed and boiled noodle products are mainly steamed bread and noodles. Adding appropriate amount of inulin to steamed bread can increase the specific volume of steamed bread and improve the texture of steamed bread. However, different types of inulin have different effects on noodles.
4. Chocolate products
Chocolate is a high-sugar and high-calorie food. The sucrose content of full-sugar chocolate is as high as 48%, which is not conducive to health. Therefore, some studies have used inulin instead of sucrose to make low-sugar or sugar-free chocolate. Products produced with inulin instead of sucrose not only have low calorie characteristics, but also can improve their texture, but the puffing still needs to be improved.
5. Ice cream
Ice cream is a popular dessert. Its fat content is 8% to 16%, and its sucrose content is 14% to 18%, which cannot meet the needs of health. Low-fat ice cream is favored by consumers because of its low calorie and low fat. accept. The type of inulin has a certain impact on the quality of ice cream, among which long-chain inulin can effectively improve the taste and color of ice cream, and at the same time increase its melting resistance and expansion rate, which can promote the development of low-fat ice cream.
