Dairy Processing and Milk Products
What this domain tests
Dairy Processing and Milk Products tests heat treatment, product standards, quality tests and small-scale processing. Maharashtra's syllabus includes khoa, paneer, dahi, ghee and shrikhand, so expect product-specific temperatures and yields.
Core rules
- Pasteurization: LTLT 63 °C for 30 minutes; HTST 72 °C for 15 seconds; UHT 135–150 °C for 1–2 seconds, then aseptic packing. Chill to 4 °C to slow spoilage.
- Standards: full cream 6% fat and 9% SNF; toned 3% fat and 8.5% SNF; double toned 1.5% fat and 9% SNF; cow milk minimum 3.5% fat and 8.5% SNF; buffalo milk 6% fat and 9% SNF.
- Tests: phosphatase test detects incomplete pasteurization; MBRT measures bacterial load; CMT is a farm mastitis test; iodine detects starch.
- Products: dahi with mesophilic culture at 37–42 °C; paneer by acid coagulation; ghee by clarification; khoa by continuous stirring and evaporation.
Worked example
Standardize 100 kg of 5.0% fat milk to 4.5% fat using skim milk of 0.05% fat. Skim milk needed = [100 × (5.0 − 4.5)] / (4.5 − 0.05) = 50 / 4.45 = 11.2 kg. Add 11.2 kg skim milk to 100 kg whole milk; the new fat percentage is (100 × 5.0) / 111.2 ≈ 4.5%. This is the principle behind toned and double-toned milk.
Traps that cost marks
Confusing HTST and LTLT; writing UHT as 100 °C; forgetting SNF; claiming pasteurized milk is sterile; using the phosphatase test as a bacterial count; failing to chill milk before processing.