agar powder is composed of agarose and agaropectin. Agar powder is insoluble in cold water, soluble in boiling water and slowly soluble in hot water. Agar powder uses neutral PH by default, generally about 7, and it cannot condense when the PH is less than 4.

agarose is a linear polymer, and its basic structure is 1,3-linked β-D- galactofuranose and 1,4-linked 3,6- dehydrated α-L- galactofuranose. Agar pectin is a heterogeneous mixture of many smaller molecules. Their structures are similar, but with sulfate and carboxyl components, their gel ability is poor. Simply put, the agar pectin in agar is removed, and the rest is agarose.

In industry, the color of agar is from white to yellowish, with gelatinous texture, odorless or slightly characteristic odor. Agar is insoluble in cold water, soluble in boiling water and slowly soluble in hot water.

Agarose is generally heated to above 9℃ to dissolve in water, and when the temperature drops to 35-4℃, it forms a good semi-solid gel, which is the main feature and foundation of its various uses. The performance of agarose gel is usually expressed by gel strength. The higher the strength, the better the gel performance. The strength of good quality agarose is usually above 12g /cm2 (1% gel concentration). The gelation of agarose is caused by the existence of hydrogen bonds, and all factors that can destroy hydrogen bonds can lead to the destruction of gelation. Agarose is hydrophilic, almost completely free of charged groups, and rarely causes denaturation and adsorption to sensitive biological macromolecules, so it is an ideal inert carrier.

during the preparation of agarose, it is necessary to remove the pectin as much as possible, otherwise there may be a very small amount of sulfate and pyruvate substituted ionization groups in agarose, which will cause electroosmosis (EEO), which will affect the movement of particles. The sulfate content of agarose with good quality is relatively low, usually below .2%, and the electroosmosis is relatively small, usually below .13. So in terms of price, agarose is much more expensive than agar.