The reason why Fehling's reagent requires a boiling water bath in the amylase specificity experiment: The experiment uses a single variable method, so adding iodine solution requires consistent environmental conditions, so the boiling water needs to be cooled down.

This experiment is to remove reducing sugar and starch from the extraction solution. There is no amylase in potatoes, and they will not hydrolyze starch to form reducing sugars. However, sweet potatoes have amylase, which hydrolyzes their own starches to form reducing sugars. Therefore, there is amylase in the A extraction solution, and there is no amylase in the B extraction solution. In this way, after adding the same amount of starch, one has reducing sugar and the other does not.

Beta-amylase is widely distributed

The difference from α-amylase is that it cleaves the α-1,4-glucan chain from the non-reducing end in units of maltose. . Mainly found in higher plants (barley, wheat, sweet potato, soybean, etc.), but also reported to exist in bacteria, milk, and mold. For unbranched substrates like amylose, maltose and a small amount of glucose can be completely decomposed.

Reference for the above content: Baidu Encyclopedia-Amylase