Enzymatic Digestion of Starch

1. Collect about 2 mL of saliva in a clean test tube.
2. Add 6 mL of neutral (pH 7) buffer solution to the saliva and mix well.
3. Pour half of the saliva mixture into another clean test tube and label these test tubes S1
   and S2 (for saliva)
4. Add about 4 mL of neutral buffer (no saliva) to each of 2 other clean test tubes and label
   these B1 and B2 (for buffer).
5. Add about 10 drops of starch solution to each of the 4 tubes (2 with saliva and 2 with
   buffer only) and mix well. Allow the mixtures to stand while you proceed with parts A
   thru E.
6. After allowing the solutions to stand for at least 30 min, test for glucose with Benedict's
   reagent and starch with iodine as described below.
7. Add 3 drops of Benedict's reagent to one tube containing saliva (S1) and to one tube
   containing buffer (B1), mix well and place both tubes in the hot water bath for several
   minutes.
8. Add 1 drop of iodine solution to the other tube containing saliva (S2) and the other tube
   containing buffer (B2) and mix well. It is not necessary to heat these 2 tubes.
9. Record your observations for these 4 tubes on the report sheet and answer the questions
   for this part.