LABORATORY 1

FOOD SCIENCE SBK3033

LAB 1: STARCH ANALYSIS

MAUREEN SANTIH ANAK AMBANG	D20141067070
SHARIFAH AWANIS BINTI SYED MOHD ASWAD	D20141067053
MOHAMAD HARITH BIN SULAIMAN	D20141067083

DATE OF EXPERIMENT: 21 FEBRUARY 2017

LECTURER: ASSOCIATE PROFESSOR DR HASIMAH ALIMON

Experiment 1

Results:

Substance	Colour change after adding iodine
10% glucose solution	Yellow solution
1% starch solution	Blue black solution
1% albumen solution	Light yellow solution
Water	Yellow solution

Discussion:

1. The substances selected for testing are examples of three of the principle chemical substances in cells, sugar (glucose), starch, protein (albumen). With which of these substances did iodine react to give a colour change?

Only starch will change from yellow solution to dark blue solution while glucose and albumen stayed unchanged which is yellow solution.

2. Does your result indicate that there is, for example, no sugar and no protein that will give a colour change with iodine?

Yes. Only starch will react with iodine to give a blue black solution.

3. What experiments would you have to carry out in order to give a confident answer to question 2?

We would have to do an experiment to test the samples from all sugar and all protein.

4. Does the result indicate that starch will always react with iodine solution to give a colour change?

From the experiment, we only confident that 1% starch solution will turn from yellow solution to blue black solution.

5. What was the point of the water in tube 4?

Water in test tube 4 act as a control of the experiment.

Experiment 2: Testing food for the presence of starch
Results:

Food sample	Colour change with iodine	Interpretation of result
Potato	Blue black solution	Starch present
Onion	Light blue solution	Starch present
Bread	Blue black solution	Starch present
Banana	Brown solution	No starch present
Apple	Yellow solution	No starch present
Dried milk	Grey solution	No starch present

Discussion:

     Based on the experiment, iodine solution is used to determine the present of starch in the food sample provided. If the starch is present in the food sample, the colour of iodine will change from yellow to dark blue. But, the solution will show negative results when there is no starch present in the food sample.

     From this experiment, the food samples that show positive results when tested with iodine solution are potato, onion and bread. This is because the oxidation was occurring within the solution of food samples and iodine solution. Oxidation causes the colour changes from yellow to dark blue. While for banana, apple and dried milk show negative result which means there are no starch present.

Conclusion:

All the food product that contain starch can be tested with iodine and it will show positive results as iodine will turn from yellow to dark blue colour to indicate the present of starch.