Educator's Guide (Grades 9-12) - Buffalo Museum of Science

EXPERIMENT:
Test for the by-products of starch
Materials:
Starch, α-amylase, pancreatin, Fehling’s solutions I and II, test tubes.
Preparation:
I. Starch solution : see above, Preparation no. I
II. Pancreatin solution: dissolve 1 “spoon tip’s worth ” of pancreatin in approx. 5ml water.
III. Fehling’s reagent: see above, Preparation no. III
Method:
Mix the starch solution (I) with 1-2ml of pancreatin solution or saliva, as appropriate, and leave for a few
minutes to react. Then carry out the Fehling’s test (see glucose test).
Observations:
The Fehling’s test is positive.
Explanation:
Pure starch solution does not reduce Fehling’s reagent (cf control experiment). Under the influence of
amylase, starch is broken down to maltose, which causes the typical Fehling’s reaction.
Note:
To show that the pancreatin preparation is sugar-free, you can carry out the Fehling’ s test with the
remainder of the solutions. They should not cause the typical change in the reagent.
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