Biology Oreo

Detection of food substances by food tests (02)Chan Tracey Wing Tung (12)Lee Hei Tung (15)Luk Ka Wing (22)Yeung Ka Tak F.3A

Objective • To test for the presence of glucose, reducing sugar, starch, fats, proteins and vitamin C by different food tests

Background information Food substance

Food test

Glucose

Using Clinistix paper

Reducing sugars

Benedict’s test

Starch

Iodine test

Fats

Grease spot test

Proteins

Using Albustix paper

Vitamin C

Using DCPIP solution

Test for food substance in solid food substance ( Oreo ) 1.Cut the food sample into small pieces. 2.Put the small pieces into a mortar and grind with a small quantity of cool distilled water using the pestle.

A.Test for glucose using Clinistix paper 1.Transfer a drop of glucose solution to the well of a spot plate.

2. Dip the test end of a Clinistix paper into the sample and observe any colour change. Use distilled water as a control .

Water

Oreo solution

Oreo

Water

Result Test end of Clinistix paper Sample

Original colour

Final colour

Glucose solution

Pink

Purple

Distilled

Pink

Pink

B. Test for reducing sugars using Bendict’s test 1.Mix equal volumes (e.g.1cm³)of glucose solution and Benedict’s solution in s test tube.

Bendict solution

2.Put the test tube into a boiling water bath. Boil the mixture for 5 mins and observe any in the mixture. After 3.Stand the test tube in a test tube rack for 15 mins and observe any change in the mixture again. Use distilled water as a control.

Water Bath:

Oreo solution Bendict

solution+ Oreo solution

Results Sample

Glucose solution Distilled

Mixture of Benedict’s solution and sample Original colour Final change Light blue Brick red precipitate Light blue

Light blue

C. Test for starch using iodine test 1.Transfer a drop of starch solution to the well of a spot plate. 2.Add a drop of iodine solution to the sample and observe any colour change. Use distilled water as a control. Oreo solution+ iodine Water + iodine

Results Iodine solution Sample

Original colour

Final colour

Starch solution

Brown

Blue-black

Distilled water

Brown

Brown

D. Test for fats using grease spot test 1.Transfer a drop of cooking oil to a filter paper and let it dry in the air for 5 mins 2.Hold up the filter paper to the light and observe any translucent spot

3.Immerse the filter Oreo solution paper into a original solvent (e.g. ether, acetone). 4.Examine the filter paper against light again. Note any change in the filter paper. Use egg white solution and distilled water as controls.

Water

Results Sample

Cooking oil Egg white solution Distilled water

Presence of translucent spot after drying? Before After immersing immersing into organic into organic solvent solvent Yes No Yes

Yes

No

Not applicable

E.Test for proteins using Albustix paper 1.Transfer a drop of egg white solution to the well of a spot plate. Oreo water solution Water Oreo solution

2.Dip the test end of an Albustix paper into the sample and observe any colour change. Use distilled water as a control.

Water

Oreo solution

Result Sample

Test and of Albustix paper Original colour

Final colour

Egg white solution

Yellow

Blue-green

Distilled water

Yellow

Yellow

F.Test for vitamin C using DCPIP solution 1.Put 1 cm3 of DCPIP solution in a test tube. 2.Add in vitamin C solution drop by drop. Stop when there is any persistent colour change.

Add in Oreo solution DCPIP solution

3.Boil a test tube of 5cm3 of vitamin C Control solution in a boiling water bath for 5 mins. (Add Water) Allow the test to cool in a breaker of cold water. 4.Use the boiled vitamin C solution and distilled water as controls.

Oreo

solution+ DCPIP solution

Results Sample

DCPIP solution Original colour

Final colour

Vitamin C solution Boiled vitamin C solution

Blue

colourless

Blue

Blue

Distilled water

Blue

Blue

Apparatus & Materials used

Apparatus & Materials used • • • • • • • • • • •

Test tube Test tube holder Filter paper Filter funnel Beaker Mortar Grind Spot plate Dropper Measuring cylinder Water boiling bath

• • • • • • •

Oreo biscuits Distilled Water Clinistix paper Bendict’s solution Iodine solution Albustix paper DCPIP solution

Conclusion • • • • • • •

In our tests, Oreo has the reaction on: Glucose (Clinistix paper) +ve Reducing sugar (Benedict’s test) +ve Starch (Iodine test) +ve Fat (Grease spot test) -ve Protein (Albustix paper) +ve Vitamim C(DCPIP solution) +ve

Experimental Errors & Improvement • Oreo should have positive result on fats. However, in our test, we have negative result since there is little amount of fat in Oreo. • We need to be more careful in cleaning all the apparatus before we use them again. Eg.There is also colour change in our control (water).