Biology
Form II
BIO-F2-06
✓ Verified TIE Syllabus
Investigation of Food Nutrients
Qualitative biochemical food testing techniques: standard laboratory procedures, positive and negative controls, observation recording, and deduction of starch, reducing sugars, non-reducing sugars, lipids, and proteins.
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🎯 Syllabus Competencies & Learning Objectives
Key Competencies
- Main: 2.0 Conduct biological investigations
- Specific: 2.1 Demonstrate mastery of basic skills for conducting biological investigations
Specific Learning Objectives
- Perform the iodine test for starch.
- Perform Benedict test for reducing sugars (glucose, maltose).
- Perform the test for non-reducing sugars (sucrose) using acid hydrolysis and neutralization.
- Perform the Biuret test for proteins.
- Perform ethanol emulsion and grease spot tests for lipids.
- Record experimental observations in standard NECTA tabular format.
📖 Comprehensive Study Notes Summary
### Standard NECTA Food Testing Protocols
| Food Substance | Test Procedure | Observation | Deduction |
| :--- | :--- | :--- | :--- |
| **Starch** | Add 2-3 drops of Iodine solution | Solution turns blue-black | Starch present |
| **Reducing Sugar** | Add equal volume of Benedict's solution, heat in boiling water bath | Color changes: Green -> Yellow -> Orange -> Brick-red ppt | Reducing sugar present |
| **Non-reducing Sugar** | Add dilute HCl, boil for 2 min. Cool, neutralize with NaOH/NaHCO3. Add Benedict and boil | Brick-red precipitate formed | Non-reducing sugar present |
| **Protein** | Add equal volume of 10% NaOH, then 2-3 drops of 1% CuSO4 (Biuret) | Solution turns purple / violet | Protein present |
| **Lipids** | Add ethanol, shake vigorously, decant into water | White cloudy emulsion forms | Lipids present |
| Food Substance | Test Procedure | Observation | Deduction |
| :--- | :--- | :--- | :--- |
| **Starch** | Add 2-3 drops of Iodine solution | Solution turns blue-black | Starch present |
| **Reducing Sugar** | Add equal volume of Benedict's solution, heat in boiling water bath | Color changes: Green -> Yellow -> Orange -> Brick-red ppt | Reducing sugar present |
| **Non-reducing Sugar** | Add dilute HCl, boil for 2 min. Cool, neutralize with NaOH/NaHCO3. Add Benedict and boil | Brick-red precipitate formed | Non-reducing sugar present |
| **Protein** | Add equal volume of 10% NaOH, then 2-3 drops of 1% CuSO4 (Biuret) | Solution turns purple / violet | Protein present |
| **Lipids** | Add ethanol, shake vigorously, decant into water | White cloudy emulsion forms | Lipids present |