Inulin molecule is polymerized by about 31 β-D-fructofuranose and 1~2 inulin residues.

Inulin is a reserve polysaccharide in plants, mainly from plants, and more than 36,000 kinds of it have been found, including 11 families of dicotyledonous plants, such as Asteraceae, Erythrina, Gentiana and other families, and monocotyledonous plants, such as Liliaceae and Gramineae. For example, inulin is abundant in the tubers of chrysanthemum, chicory, the tubers of geranium peony (dahlia), and the roots of artichoke, of which the inulin content of chrysanthemum is the highest.

Fructose residues can be connected to each other by β-2,1-bonds. It is a linear straight-chain polysaccharide linked by β(1→2) glycosidic bonds from D-fructose, often with a glucose residue at the end, with a degree of polymerization (DP) of 2~60, of which the average degree of polymerization DP ≤ 9 inulin is also known as short-chained inulin, and the inulin extracted from natural plants contains both long-chained and short-chained. The molecular formula of inulin is expressed as GFn, where G stands for terminal glucose unit, F stands for fructose molecule, and n stands for the number of units of fructose.

Physical and Chemical Properties of Inulin

Dried inulin is a white amorphous powder. Usually short-chain inulin is more soluble in water than long-chain inulin, and the solubility of inulin will increase significantly with the increase of temperature, the solubility of common inulin is about 6% at 10℃, and about 33% at 90℃. Short-chain inulin contains more monosaccharides and disaccharides, and its sweetness is about 30%~50% of that of sucrose. Ordinary inulin is slightly sweet, about 10% of the sweetness of sucrose, and long-chain inulin has almost no sweetness.

When the concentration of inulin solution reaches 10%-30%, it starts to form a gel, and when the concentration reaches 40%-50%, it can form a very solid gel. The viscosity of the gel decreases with the increase of temperature. Long-chain inulin has a relatively small solubility and forms imperceptible microcrystals in water, which interact with each other to form a smooth, creamy structure with a taste similar to fat.

Inulin is highly hygroscopic and has the ability to bind free water, which can reduce water activity. This can be fully utilized in food processing to slow down the evaporation of water, prevent the product from becoming tasteless, and extend the shelf life and shelf life of food.

Refer to Baidu Encyclopedia - Inulin