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Questions and Answers
What is the purpose of adding 2-3 drops of iodoform reagent to each tube?
What is the purpose of adding 2-3 drops of iodoform reagent to each tube?
What is the result of a positive iodoform test?
What is the result of a positive iodoform test?
Which reagent is used to detect the presence of proteins?
Which reagent is used to detect the presence of proteins?
What is the result of a positive Vibure test?
What is the result of a positive Vibure test?
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Which reagents are used to detect the presence of reducing sugars?
Which reagents are used to detect the presence of reducing sugars?
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What is the result of a positive Fehling and PeLienk test?
What is the result of a positive Fehling and PeLienk test?
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Which reagent is used to detect the presence of lipids?
Which reagent is used to detect the presence of lipids?
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What is the result of a positive Sudan 3 test?
What is the result of a positive Sudan 3 test?
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Study Notes
Biomolecules Identification
- Identifying biomolecules in 10 food samples using different reagents:
- Iodoform test for starch
- Vibri reagent for proteins
- Fehling and PeLienk reagents for reducing sugars
- Sudan 3 and vegetal dye for lipids
Starch Identification
- Iodoform test:
- Add 2-3 drops of iodoform reagent to each tube
- Shake the tubes well
- Observe color change:
- Positive result: blue-black color (starch present)
- Results:
- Tube 6 (potato): positive result
- Tube 7 (sausage): positive result
- Tube 8 (starch): positive result
- Tube 9 (milk powder): positive result
Protein Identification
- Vibure reagent:
- Add 5 drops of Vibure reagent to each tube
- Shake the tubes well
- Observe color change:
- Positive result: purple color (proteins present)
- Results:
- Tube 4 (egg white): strong positive result
- Tube 2 and Tube 7: weaker positive results
- Milk and milk powder: may contain proteins, but white color masks the purple color
Reducing Sugars Identification
- Fehling and PeLienk reagents:
- Add 5 drops of Fehling's reagent to each tube
- Add 5 drops of PeLienk reagent to each tube
- Observe color change:
- Positive result: red brick color (reducing sugars present)
- Results:
- Tube 3 (glucose): strong positive result
Lipid Identification
- Sudan 3 and vegetal dye:
- Add 1 mL of vegetal dye to each tube
- Add 3 drops of Sudan 3 to each tube
- Observe color separation:
- Positive result: Sudan 3 mixes with lipids, while vegetal dye stays at the bottom
- Results:
- Tube 10 (oil): Sudan 3 mixes with lipids, while vegetal dye stays at the bottom
Biomolecules Identification
- 4 types of biomolecules identified in 10 food samples using different reagents
- Reagents used: iodoform, Vibure, Fehling, PeLienk, Sudan 3, and vegetal dye
Starch Identification
- Iodoform test detects starch
- Procedure: add 2-3 drops of iodoform reagent, shake, and observe color change
- Positive result: blue-black color indicates starch presence
- Results: starch present in Tubes 6 (potato), 7 (sausage), 8 (starch), and 9 (milk powder)
Protein Identification
- Vibure reagent detects proteins
- Procedure: add 5 drops of Vibure reagent, shake, and observe color change
- Positive result: purple color indicates protein presence
- Results: strong positive result in Tube 4 (egg white), weaker positive results in Tubes 2 and 7
Reducing Sugars Identification
- Fehling and PeLienk reagents detect reducing sugars
- Procedure: add 5 drops of Fehling's reagent and 5 drops of PeLienk reagent, observe color change
- Positive result: red brick color indicates reducing sugar presence
- Results: strong positive result in Tube 3 (glucose)
Lipid Identification
- Sudan 3 and vegetal dye detect lipids
- Procedure: add 1 mL of vegetal dye and 3 drops of Sudan 3, observe color separation
- Positive result: Sudan 3 mixes with lipids, while vegetal dye stays at the bottom
- Results: positive result in Tube 10 (oil)
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Description
Identify biomolecules in 10 food samples using various reagents such as iodoform, Vibri, Fehling, and others. Learn how to detect starch, proteins, reducing sugars, and lipids in different food samples.
