Biology Presentation

Biology presentation Group 8:

Chan Siu Hong Lam Kwan Chek Lee Nok Him Lo Hall Wong Tsz Ki

( 24)( 27)( 30)( 34)(

Introduction Our group have bought a can of condensed milk ( 煉奶 ) to test for the presence of glucose, reducing sugar, starch, fats, proteins and vitamin C by different food tests.

Preparation We opened the can of condensed milk and pour the contents into a beaker until the beaker is 50mL full. Then add some water to dilute the milk. The condensed milk used in the tests are taken from here by using dropper.

Preparation Materials prepared 1 test tube rank

1 can of condensed milk

1 beaker 1 spot plate 1 boiling water bath 1 tube of cooking oil 2 filter papers 2 Albustix papers 10 test tubes

1 1 1 1 2 2

bottle of Benedict’s solution bottle of DCPIP solution bottle of iodine solution bottle of distilled water droppers Clinistix papers

Tests order Test for glucose Test for reducing sugars Test for fats Test for starch Test for vitamin C Test for proteins

First Test: Test for glucose Steps: 1. Transfer a drop of condensed milk to the well of a spot plate. Also add another drop of distilled water to another well of the spot plate, which is used as a control.

First Test: Test for glucose Steps: 2. Dip the test end of a Clinistix paper into the sample and observe any colour change.

First Test: Test for glucose Result: The colour changed from yellow to light green. After test for water (Original colour) After test for condensed milk

Second Test: Test for reducing sugars Steps: 1. Mix equal volumes of condensed milk and Benedict’s solution in a test tube. Also prepare another test tube contains mixture of distilled water and Benedict’s solution. mixture of condensed milk and Benedict’s solution mixture of distilled water and Benedict’s solution

Second Test: Test for reducing sugars Steps: 2. Put the test tubes into a boiling water bath. Boil the mixture for 5 minutes and observe any change in the mixture.

Second Test: Test for reducing sugars Steps: 3. Stand the test tubes in a test tube rank for 15 minutes.

Second Test: Test for reducing sugars Result: The colour changed from light blue to orange. Mixture of distilled water and Benedict’s solution (Original colour) Mixture of condensed milk and Benedict’s solution

Third Test: Test for fats Steps: 1. Transfer a drop of condensed milk to a filter paper and another drop of distilled water. Let the two papers dry in the air for 5 minutes.

Third Test: Test for fats Steps: 2. Put the two papers under the light. Observe any translucent spot.

Third Test: Test for fats Result: The condensed milk spot becomes translucent. Cooking oil spot (translucent)

Condensed milk spot (translucent)

Fourth Test: Test for starch Steps: 1. Transfer a drop of condensed milk to the well of a spot plate. Also transfer a drop of distilled water to another well of the spot plate.

Fourth Test: Test for starch Steps: 2. Add a drop of iodine solution to the sample and observe any colour change.

Fourth Test: Test for starch Result: There is no visible change.

Distilled water with iodine solution Condensed milk with iodine solution

Fifth Test: Test for vitamin C Steps: 1. Add a few drops of DCPIP solution in two test tubes.

Fifth Test: Test for vitamin C Steps: 2. Add in same amount of condensed milk. Stir them well then. Also add another tube of distilled water.

Fifth Test: Test for vitamin C Steps: 3. Put the test tubes in a boiling water bath for 5 minutes. Then put them into a beaker of cool water.

Fifth Test: Test for vitamin C Result: The solution change from blue into light blue.

Condensed milk solution

Sixth Test: Test for proteins Steps: 1. Transfer a drop of condensed milk to the well of a spot plate. Also add distilled water to another well of the spot plate

Sixth Test: Test for proteins Steps: 2. Dip the test of an Albustix paper into the sample and observe any colour change.

Sixth Test: Test for proteins Result: The Albustix paper turns from yellow to light green.

After test for condensed milk

After test for distilled water (Original colour)

Conclusion Test

Original colour Yellow

Final colour Light green Light blue Orange

Meaning

DCPIP test

Blue

[]Vitamin C

Albustix paper

Yellow

Clinistix paper Benedict’s test Grease spot test Iodine test Brown

[]Glucose

[]Reducing sugar Transluc []Oil ent Brown []Starch Light blue Light green

[]proteins

Thanks for watching!! Goodbye…