1) Iodine test.
Iodine test distinguishes starch. It helps in distinguishing a polysaccharide from monosaccharide, disaccharides and other polysaccharides. The test is also called iodine staining. The iodine reacts with coiled polymer molecules and turn bluish black. Non-coiled starch does not react with iodine thereby no bluish color observed. A positive result is when there is the presence of the bluish black color.
1. Put two drops of the solutions to be tested in three different test-tubes.
2. Add two drops of the IKI reagent to each of the tubes containing different sugar solutions.
3. Keep the sugar at room temperature for 10 minutes.
4. Record your results in the table below
Discussion and conclusion
The change in color from yellowish white to bluish black indicated the presence of starch in the solution. A positive result was indicated by a change in color while a negative result was indicated by no color change meaning that there was no starch present.
2) Microscopic examination.
Microscopic examinations are not very common and hence not performed routinely. They are only performed if there are some forms of abnormal findings on the physical or chemical examination. Urinalysis is a form of microscopic examination which is performed on urine sediment.
1. Take the urine samples and place them in a test-tube
2. Centrifuge the urine to concentrate the substances it at the bottom of a tube.
3. Discard the fluid at the top of the tube
4. Examine the drops of fluid remaining under a microscope
5. Count the number of cells, crystals and other substances in the sample and record them as LPF (low Power Field) or HPF (High Power Field)
6. The remaining entities are then classified as few, moderate or many.
3) RVA test.
1. Rapid visco analyzer
2. Falling number lab mill with a 0.8mm screen.
3. Laboratory balance
4. Sample canisters
5. Robot dispenser
1. Distilled water
2. Calibration oil
1. Switch on the RVA unit and allow it to warm up for 30 minutes
2. Check the calibration offset for accuracy
3. Analyze the sample using the stirring Number (SN) profile
4. Determine the moisture content
5. Grind a representative sample
6. Stir the ground sample thoroughly
7. Add 25 ml of stilled water
8. Mix the contents of the canister
9. Insert the canister into the instrument and start the test by pressing the tower down.
10. After recording the final viscosity convert the displayed unit into RVU by dividing by 12
4) Retrogradation and Gel formation.
Retrogradation is a form of reaction that takes place in gelatinized starch during the alignment of the amylase and amylopectin chains thus causing the liquid to gel
5) Temperature and ph.
1. Take five test-tubes and mark each one of them 2 cm from the bottom using a wax pencil
2. Number the tubes 1 – 5
3. Fill all the tubes with milk to the 2cm mark
4. To tube 1, add three drops of rennin and place it in a room temperature for fifteen minutes
5. Place tube 2 next to tube 1 with the same conditions but without rennin to act as a control
6. To test tube 3 add three drops of rennin and place it in a an incubator set a temperature of 37 degrees for 15 minutes
7. Test tube 4 is to serve as a control to tube 3. It should be placed in the incubator but without rennin added to it.
8. In tube 5 add three drops of boiled rennin to the milk and place it in the incubator at a temperature of 37 degrees
9. Observe the milk in the tubes after 15 minutes and record the results in the table below