What kind of starch do you have? What's the difference between them?

The starch is the most frequently contacted article in our daily life, but it is not as simple as we think. What are the types of starch? What are the differences between them? We mainly understand the following three kinds of starch: 1, amylose 2, amylopectin 3, soluble starch.

Common features:
White powder (soluble starch dominance is also pale yellow); odorless, odorless; hygroscopic; insoluble in cold water, ethanol and ether.

Differences(Huibai reagent: http://www.hnhbsj.com):
1. Structurally: amylose is a D-glucosyl linked polysaccharide chain with a-(1,4) glycoside bond, amylopectin is composed of a-(1,4) glycoside bond and 4% a-(1,6) glucoside bond linked branched chain glucose unit. Soluble milk powder, also called starch dextrin, is a derivative of starch after a certain proportion of acid-base reaction, and its molecular weight is smaller.

2, molecular weight: amylose (C6H10O5) 5 × 10 5 ~ 2 × 10 ~ 6; amylopectin (C6H10O5) 15 ~ 400 × 10 ~ 6; soluble starch is disaccharide, molecular weight is 342.29.

The principle of iodine in starch is due to the fact that iodine molecules are embedded in the spiral space of starch and combined with Van der Waals force to form a complex (that is, inclusion). Amylose is blue (maximum absorption wavelength is 650nm), amylopectin is purplish red (maximum absorption wavelength is 540nm), while soluble starch is usually brown red, light red or colorless.

4, Biological use: amylose is the role of a-amylase.

5. Amylose can also form insoluble complexes with n-butanol, amyl alcohol and thymol, which can be distinguished from amylopectin. Amylopectin was used for the determination of amylopectin in biochemical studies. Soluble starch: used as thickener, stabilizer, filler, sugar-free drug excipient, etc. The saccharification activity of malt starch was determined. Iodine titration indicator. Test for non-protein nitrogen in blood. Serum sodium was determined.

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