Food Chemistry Tests
Testing for Starch and Lipids in Common Foods
Test common food items for the presence of starch (using iodine solution) and lipids (using Sudan IV stain). Drag food samples to the test tubes and observe the color changes.
Food Chemistry Tests
Iodine Solution
Sudan IV
Starch Test
Lipid Test
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Observation:
Drag food items to the test tubes, then perform starch and lipid tests. Observe the color changes.
The Science Behind Food Tests
Starch Test (Iodine Solution):
- Positive result: Blue-black color change
- Iodine forms a complex with starch molecules
- Works best on starchy foods like bread, potatoes, rice
- No color change with non-starchy foods (remains brown/yellow)
Lipid Test (Sudan IV Stain):
- Positive result: Red-stained layer separates
- Sudan IV is a fat-soluble dye that stains lipids red
- Works on fatty foods like cheese, butter, oils
- No staining with non-fatty foods (dye remains in solution)
Expected Results:
| Food Item | Starch Test | Lipid Test | Explanation |
|---|---|---|---|
| Bread | Positive (blue-black) | Negative | Made from starch-rich flour |
| Cheese | Negative | Positive (red layer) | High in milk fats |
| Potato | Positive (blue-black) | Negative | Starch is storage carbohydrate |
| Butter | Negative | Positive (red layer) | Almost pure fat |
| Rice | Positive (blue-black) | Negative | High starch content |
| Oil | Negative | Positive (red layer) | 100% fat |
Real-World Applications:
- Food quality testing
- Nutritional analysis
- Food labeling verification
- Scientific research on food composition
- Detecting adulteration in food products
