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Starch hydrolysis refers to the hydrolysis reaction process of starch. After starch enters the human body, some starch is hydrolyzed by amylase contained in saliva to produce maltose. Under the action of amylase secreted by small intestine and pancreas, the remaining starch is hydrolyzed to maltose.
Under the catalysis of maltase in intestinal juice, maltose is hydrolyzed into glucose which can be absorbed by human body and used for the nutritional needs of human tissues. Equation: c6h10o5n+(n) H2O → nc6h12o6.
Starch is a high molecular compound, which can be hydrolyzed under certain conditions. Dilute sulfuric acid can be added and heated. Starch is not only an important polysaccharide, but also a natural polymer compound with relatively large molecular weight. Although it is sugar, it has no sweetness. It is white powder and insoluble in cold water. In hot water, starch granules will expand, some starch will be dissolved in water, and the other part will be suspended in water, forming a gelatinous starch paste.
experimental method
Add 3ml of sodium hydroxide solution into another test tube 4, and drop 4 drops of 2% copper sulfate solution, and blue copper hydroxide precipitate will form immediately. Then drop 1ml hydrolysate into the test tube 3, shake it evenly, and heat it to boiling with alcohol lamp. The color of the solution often changes from blue, yellow, green, yellow and blue to red. Finally, a red precipitate is formed.
The reason is that copper hydroxide is reduced to produce red cuprous oxide, which is insoluble in water. Experimental conclusion: Starch can be hydrolyzed under the catalysis of acid. Hydrolysis process of starch: dextrin with small molecular weight (the product of incomplete hydrolysis of starch) is formed, and dextrin continues to hydrolyze to form maltose, and the final hydrolysis product is glucose.
Experimental extension design: How to verify the catalytic effect of sialidase on starch hydrolysis? (Note: When using saliva as a catalyst to hydrolyze starch, the temperature should not exceed 45℃, because sialidase will lose its activity if the temperature is too high, and the most suitable temperature is 37-40℃. Some bacteria can secrete amylase extracellular enzyme, hydrolyze starch into maltose and glucose, and then be absorbed and utilized by bacteria. Starch will not turn blue when it meets iodine after hydrolysis.