Biology Oreo
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Transcript of 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 testGlucose Using Clinistix paperReducing sugars Benedict’s test
Starch Iodine test
Fats Grease spot test
Proteins Using Albustix paperVitamin 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 paper1.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 .
Oreo solution
Water
Water
Oreo solution
Result
SampleTest end of Clinistix paper
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.
2.Put the test tube into a boiling water bath. Boil the mixture for 5 mins and observe any in the mixture.
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.
Bendict solution
Oreo solution
After Water Bath:
Bendict solution+Oreo solution
Results
Sample Mixture of Benedict’s solution and sample
Original colour
Final change
Glucose solution
Light blue Brick red precipitate
Distilled 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
SampleIodine solution
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 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.
Oreo solutionWater
Results
Sample
Presence of translucent spot after drying?
Before immersing
into organic solvent
After immersing
into organic solvent
Cooking oil Yes No
Egg white solution
Yes Yes
Distilled water
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 solution
Water
Oreo solution
water
2.Dip the test end of an Albustix paper into the sample and observe any colour change. Use distilled water as a control.
Oreo solution
Water
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.
DCPIP solution
Add in Oreo solution
3.Boil a test tube of 5cm3 of vitamin C solution in a boiling water bath for 5 mins. Allow the test to cool in a breaker of cold water.
4.Use the boiled vitamin C solution and distilled water as controls.
Control
(Add Water)
Oreo
solution+DCPIP solution
Results
Sample DCPIP solution
Original colour
Final colour
Vitamin C solution
Blue colourless
Boiled vitamin C solution
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).