How to Test Milk for Adulteration (Urea, Detergent, Starch)
Detect Urea, detergent, and starch adulteration in milk To learn more about food safety tests and home adulteration detection, read our guides on Honey and Sugar.
Inspection Guide
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Milk Purity and Adulteration Detection
Milk is frequently adulterated with water, urea, detergent, and starch to increase volume and thickness.
1. The Shake Test (Detergent Check):
Shake a small amount of milk in a glass bottle or container. Pure milk forms small bubbles that disappear quickly. Detergent-adulterated milk forms thick, dense foam that persists for a long time.
2. The Slip Test (Water Dilution):
Put a drop of milk on a polished slanted surface (like a steel plate). Pure milk flows slowly, leaving a distinct white trail behind. Water-diluted milk flows instantly without leaving any trail.
3. The Iodine Test (Starch Detection):
Add a drop of iodine to a small sample of milk. If the milk turns blue-black, it indicates the presence of starch or flour used as a thickener.
4. The Texture Test (Urea/Soap):
Rub a few drops of milk between your fingers. If it feels unusually slippery or soapy, it likely contains detergent or urea.
Quick Safety Tips
- Dense foam after shaking indicates detergent
- Pure milk leaves a white trail on slanted surfaces
- Iodine test for starch/flour detection
- Buy from trusted dairies and check for organic certification
Primary Chemical Concerns
Health Risks & Impacts
Multilingual Local Names
Common Storage Pests
Spoilage Bacteria
high riskMicroorganisms like Lactobacillus that cause milk to sour or curdle.
Detection
- Sour or "off" smell
- Separation of solids (curdling)
Prevention
- Keep refrigerated below 4°C
- Ensure the container is sanitized
Corrective Action: What to do?
Discard immediately if sour or curdled.
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