Milk, Meat, Fish, and Poultry Processing
Scope of the domain
This domain tests the handling and processing of milk, meat, fish and poultry, including pasteurisation, homogenisation, dairy products, rigor mortis, chilling, curing and spoilage control.
Core rules and concepts
- Milk contains water, lactose, fat, protein, minerals and vitamins. Pasteurisation commonly uses 63°C for 30 minutes or 72°C for 15 seconds, followed by rapid cooling.
- Homogenisation reduces fat globule size and prevents cream separation; it does not sterilise milk.
- Cream separation relies on density difference in a centrifuge.
- Meat undergoes rigor mortis after slaughter; chilling and conditioning improve tenderness. Curing uses salt, nitrite and sometimes smoke.
- Fish spoils faster than meat because of high moisture, neutral pH, enzymes and psychrotrophic bacteria. Rapid chilling and freezing are essential.
- Poultry processing requires scalding, defeathering, evisceration, chilling and hygienic packing.
Worked example
Milk is heated at 63°C for 30 minutes, then cooled to 4°C. Name the process and state its limitation. Reasoning: this is low-temperature long-time (LTLT) pasteurisation. It kills vegetative pathogens such as Salmonella and E. coli and inactivates alkaline phosphatase, but it does not kill heat-resistant spores. The product is not sterile and must be refrigerated. If left warm, surviving spores and post-process contaminants can grow.
Traps that cost marks
- Saying homogenisation sterilises milk; it only stabilises the emulsion.
- Treating pasteurised milk as shelf-stable without refrigeration.
- Forgetting that fish spoils faster than meat under the same conditions.
- Ignoring nitrite safety in curing; excessive nitrite is a health hazard.