chemical tests for nutrients. the test for starch
TRANSCRIPT
Chemical Tests for Chemical Tests for
NutrientsNutrients
The Test for The Test for STARCHSTARCH
The Test for The Test for STARCHSTARCH
Reminder: Starch is a complex Reminder: Starch is a complex carbohydrate, which is our major carbohydrate, which is our major source of food energy.source of food energy.
The Test for The Test for STARCHSTARCH
Place a few drops of the unknown Place a few drops of the unknown in a well on a spot platein a well on a spot plate
The Test for The Test for STARCHSTARCH
Place a few drops of the unknown Place a few drops of the unknown in a well on a spot platein a well on a spot plate
Add about 2 drops of Iodine Add about 2 drops of Iodine SolutionSolution
The Test for The Test for STARCHSTARCH
Place a few drops of the unknown Place a few drops of the unknown in a well on a spot platein a well on a spot plate
Add about 2 drops of Iodine Add about 2 drops of Iodine SolutionSolution
Wait up to 30 secondsWait up to 30 secondsfor a colour changefor a colour change
The Test for The Test for STARCHSTARCH
The colours The colours black, dark purple, or black, dark purple, or dark blue indicate starch is presentdark blue indicate starch is present
The Test for The Test for STARCHSTARCH
The colours The colours brown, yellow, or not brown, yellow, or not changed, mean that there is no changed, mean that there is no starchstarch
Test for Test for Reducing SugarsReducing Sugars
Test for Test for Reducing SugarsReducing Sugars
Note: Glucose is a reducing sugar, Note: Glucose is a reducing sugar, so we use this as a so we use this as a test for test for glucoseglucose..
Test for Test for Reducing SugarsReducing Sugars
This test requires heating in a This test requires heating in a water bath, at 40water bath, at 40ooC to 50C to 50ooC for 5 C for 5 minutes.minutes.
Test for Test for Reducing SugarsReducing Sugars
This test requires heating in a This test requires heating in a water bath, at 40water bath, at 40ooC to 50C to 50ooC for 5 C for 5 minutes.minutes.
The reagent used is called The reagent used is called Benedict’s Solution.Benedict’s Solution.
Test for Test for Reducing SugarsReducing Sugars
Place about 5 mL of the unknown Place about 5 mL of the unknown solution in a test tube.solution in a test tube.
Test for Test for Reducing SugarsReducing Sugars
Place about 5 mL of the unknown Place about 5 mL of the unknown solution in a test tube.solution in a test tube.
Add about 10 drops of Benedict’s Add about 10 drops of Benedict’s Solution.Solution.
Test for Test for Reducing SugarsReducing Sugars
Place about 5 mL of the unknown Place about 5 mL of the unknown solution in a test tube.solution in a test tube.
Add about 10 drops of Benedict’s Add about 10 drops of Benedict’s Solution.Solution.
Place the test tube in a water bath, Place the test tube in a water bath, at a temperature between 40at a temperature between 40ooC C and 50and 50ooC for 5 minutesC for 5 minutes
Test for Test for Reducing SugarsReducing Sugars
If the solution turns orange after If the solution turns orange after heating, the result is positive, and heating, the result is positive, and glucose is present.glucose is present.
Test for Test for Reducing SugarsReducing Sugars
Other shades of orange or yellow Other shades of orange or yellow can also mean that reducing can also mean that reducing sugars are present.sugars are present.
Test for Test for Reducing SugarsReducing Sugars
If the solution stays blue after If the solution stays blue after heating, the result is negative, and heating, the result is negative, and glucose is absent.glucose is absent.
Test for Test for Reducing SugarsReducing Sugars
A green or brownish colour can A green or brownish colour can result if traces of glucose are result if traces of glucose are present.present.
Test for Test for Reducing SugarsReducing Sugars
A green or brownish colour can A green or brownish colour can result if traces of glucose are result if traces of glucose are present.present.
(‘traces’ means very small amounts)(‘traces’ means very small amounts)
Test for Test for ProteinProtein
This is a molecule of albumin, the protein in egg white
Test for Test for ProteinProtein
The test for protein does not The test for protein does not require heating, and so, could be require heating, and so, could be performed either in a test tube, or performed either in a test tube, or on a spot plate.on a spot plate.
Test for Test for ProteinProtein
The test for protein does not require The test for protein does not require heating, and so, could be performed heating, and so, could be performed either in a test tube, or on a spot plate.either in a test tube, or on a spot plate.
In this presentation, we shall use test tubes. In this presentation, we shall use test tubes. You may use spot plates in the lab.You may use spot plates in the lab.
Test for Test for ProteinProtein
Place about 5mL of the unknown Place about 5mL of the unknown solution in a test tube.solution in a test tube.
Test for Test for ProteinProtein
Place about 5mL of the unknown Place about 5mL of the unknown solution in a test tube.solution in a test tube.
Add about 10 drops of Biuret Add about 10 drops of Biuret Reagent.Reagent.
Test for Test for ProteinProtein
Place about 5mL of the unknown Place about 5mL of the unknown solution in a test tube.solution in a test tube.
Add about 10 drops of Biuret Add about 10 drops of Biuret Reagent.Reagent.
Mix and look for a colour change.Mix and look for a colour change.
Test for Test for ProteinProtein
If the solution becomes purple, If the solution becomes purple, violet, or lavender, it means that violet, or lavender, it means that protein was present.protein was present.
different positive results
Test for Test for ProteinProtein
If the solution stays pale blue, it If the solution stays pale blue, it means that there was no protein in means that there was no protein in the sample.the sample.
Negative result
Test for Test for FatFat
Test for Test for FatFat
Often called the grease spot test….Often called the grease spot test….
Bag of samosasBag of churros
Greasy French Fries
Test for Test for FatFat
Often called the grease spot test….Often called the grease spot test….
Fat of any type will make paper translucent (light shows through), without drying up.
Test for Test for FatFat
Often called the grease spot test….Often called the grease spot test….
Simple, yet effective!
Let’s recap:Let’s recap:
Let’s Recap:Let’s Recap:
Starch Test:Starch Test:
Let’s Recap:Let’s Recap:
Starch Test: Starch Test: – iodine turns from brown to blackiodine turns from brown to black
Let’s Recap:Let’s Recap:
Starch Test: Starch Test: – iodine turns from brown to blackiodine turns from brown to black
Glucose Test:Glucose Test:
Let’s Recap:Let’s Recap:
Starch Test: Starch Test: – iodine turns from brown to blackiodine turns from brown to black
Glucose Test:Glucose Test:– benedict’s turns from blue to orange benedict’s turns from blue to orange
with gentle heating (50with gentle heating (50ooC)C)
Let’s Recap:Let’s Recap:
Starch Test: Starch Test: – iodine turns from brown to blackiodine turns from brown to black
Glucose Test:Glucose Test:– benedict’s turns from blue to orange benedict’s turns from blue to orange
with gentle heating (50with gentle heating (50ooC)C) Protein Test:Protein Test:
Let’s Recap:Let’s Recap:
Starch Test: Starch Test: – iodine turns from brown to blackiodine turns from brown to black
Glucose Test:Glucose Test:– benedict’s turns from blue to orange benedict’s turns from blue to orange
with gentle heating (50with gentle heating (50ooC)C) Protein Test:Protein Test:
– biuret turns from blue to violetbiuret turns from blue to violet
Let’s RecapLet’s Recap
And Finally Fat...And Finally Fat...
The Grease Spot...
Now you are all expert nutrient Now you are all expert nutrient testers.testers.
Next, The Lab!Next, The Lab!