Comparison of amylase and hydrochloric acid hydrolysis optical rotation
Starch is a high-molecular carbohydrate composed of structural amylose and amylopectin, which is the main source of human energy and nutrients. There is a special amylose measuring instrument for the determination of amylose content. With the development of science and technology, corn starch produced by corn deep processing has been widely used in the production of raw materials for food, medicine and light industry. Therefore, how to quickly and accurately determine the content of starch in corn, increase its economic value and food quality, is of great significance to the rational use of corn and its by-products, selection of good varieties, and scientific grain storage.
Amylase method and hydrochloric acid hydrolysis optical method:
Principle: The former is a sample after removing fat and soluble sugars, in which α-starch is hydrolyzed into disaccharides by amylase, disaccharides are then hydrolyzed by hydrochloric acid into reducing monosaccharides, and finally determined by reducing sugar and converted into starch. The latter is the hydrolysis of starch under the action of dilute hydrochloric acid, and then the polarimetry of the hydrolyzate is determined with a polarimeter to determine the starch content.
Test method: the former is to weigh 2.00g ~ 5.00g (over 40 mesh) sample placed in a funnel containing folded filter paper, first with 50ml diethyl ether five times to remove fat, and then washed with about 100ml diethyl ether to remove soluble sugars The residue was transferred to a 250 ml beaker and the filter paper and funnel were washed with 50 ml of water and the wash solution was incorporated into the beaker. The beaker was placed in a boiling water bath and heated for 15 minutes to gelatinize the starch, then left to cool to below 60° C., add 20 ml of α-amylase solution, heat and hydrolyze for 1 hour at 55° C. to 60° C. in a constant temperature water bath, and stir frequently. Take 1 drop of the enzymolysis solution and 1 drop of iodine solution should not be blue, if it is blue, heat the gelatinization and add 20 ml of α-amylase solution, and continue to keep warm until iodine is not blue. Heated to boiling, cooled, transferred to 250ml volumetric flask and add water to volume, mix and filter. Discard the initial filtrate. Take 50ml filtrate, place in 250ml Erlenmeyer flask, add 5ml hydrochloric acid, install reflux condenser, reflux in boiling water bath for 1h. After cooling, add 2 drops of methyl red indicator solution. Neutralize with sodium hydroxide solution. Transfer the solution to a 100 ml volumetric flask. Wash the Erlenmeyer flask. Wash the solution into a 100 ml volumetric flask. Add water to the mark. All spare. With the treated sample according to GB/T 5009.7 operation, the determination of reducing sugar content, while measuring 50ml water and the same amount with the sample processing. The latter is to weigh 5.00g (over 40 mesh) of the sample in a 250ml Erlenmeyer flask and add 25ml of 1% hydrochloric acid solution to mix evenly, then add 25ml of 1% hydrochloric acid solution, and immersed in a boiling water bath for 15min (Stirring 3~ 5min) After the completion of the hydrolysis, add 30ml of warm water, cool the conical flask in a cold water bath, add 5.0ml of 10% phosphotungstic acid solution, and transfer to a 100ml volumetric flask. Wash the conical flask with water and transfer it to the volumetric flask. Medium, dilute to the mark with water, filter after standing (discard the original liquid 10~15ml).
Assay process: The former is an alpha-amylase solution and a blank test is performed in the same manner as the reagent. In the latter case, the optical rotation was measured by injecting a filtrate into a rotating light tube having a length of 1 dm or 2 dm. According to the same method as reagent blank test.
Measurement time: The former is 1 sample after pasting for 15 minutes after removal of fat and soluble sugar. 2 Add the amylase to hydrolyze for 1 hour until the enzymolysis is complete. 3 Add acid to continue condensing reflux for 1 h. The latter is added hydrochloric acid hydrolysis 15min.
In addition, the determination of starch content, as well as corresponding instruments, such as amylose analyzer, it can determine starch content in rice, corn, wheat and other crops.
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