Milk production, collection and quality testing
What this domain tests
This domain covers clean milk production, milking and collection hygiene, chilling, and platform/rapid quality tests used before acceptance. Questions often ask why a test is done and how a result is interpreted, not just the test name.
Core rules
- Use healthy animals, clean udder and teats, foremilk stripping, and sanitized stainless-steel or food-grade equipment.
- Cool raw milk rapidly, commonly to about 4°C, and keep it cold through collection and transport.
- Reject milk with off-odour, flakes, clots, or positive alcohol/clot-on-boiling tests.
- Screening tests include organoleptic, alcohol, clot-on-boiling, MBRT/resazurin, and adulteration tests.
- MBRT is a bacterial-load indicator: faster decolorization means more active bacteria and poorer keeping quality.
- Preservatives are for laboratory samples, not for milk intended for sale.
Worked example
Two tanker samples are tested by MBRT. Sample A is still blue at 8 hours; sample B is colourless at 30 minutes. A is acceptable for further processing, while B indicates heavy microbial activity and should be rejected or investigated. The reasoning is inverse: the dye is reduced faster when bacteria are multiplying rapidly, so a short reduction time is a warning sign.
Traps
The alcohol test detects instability of milk proteins, not a precise acidity value. MBRT is a screening test, not a legal composition test. Do not assume pasteurized milk can be handled like raw milk; post-pasteurization contamination is a separate risk. Never add formalin or another preservative to saleable milk.