Properties of Agar
The agar is divided into two polysaccharides including agarose and agaropectin according to its types of origin, habitats, and production methods.
The ratio between agarose and agaropectin is 70% to 30%. Since the agarose is a neutral polysaccharide, it tends to exist in gel form and increases the strength. On the other hand, the acidic polysaccharide agaropectin has a weak gel property and increases the viscoelasticity.
It contains 13~24% of water, 70~85% of nitrogen-free extract (sugar), 1.5~3.0% of crude protein, 0.2~0.3% of ether extract, 0.5~0.8% of crude fiber and 1~3% of ash content. It has more than 20 times of water absorption property compared to the dried products.
The physical properties of agar include fixedness, viscoelasticity, and conservativeness. Since agar has opposing properties, fixedness and conservativeness, it is used as a stabilizer, extender, former, thickening agent, anti-drying agent and property maintaining agent by controlling the two opposing physical properties.
The agar solution forms a gel at 32-43℃, indicating that it is more likely to form gel than any other gel-forming material, and the once the gel is formed, it does not melt below 80-85℃. In addition, even when gelation and dissolution are repeated, the original agar gel properties do not change, so that the transparent agar gel is easy to be colored, and when added with sugar, glucose, glycerin, etc., the refractive index increases and becomes glossy. Because of its unique and odorless properties, it is very suitable to use as food additives. In recent years, carbohydrate, which is a main component of agar, has been attracting attention as a material for diet foods because of its poor digestion and absorption.