Meat, Poultry, Fish and Egg Processing
Meat, Poultry, Fish and Egg Processing
This domain tests post-mortem changes, curing, smoking, freezing, spoilage indicators and egg quality.
Core rules
- Rigor mortis: after slaughter, ATP falls and muscles stiffen; pH declines. Conditioning follows. Freezing before rigor can cause cold shortening and tough meat.
- Preservation: chilling, freezing, curing (salt, nitrite), smoking, drying and canning. Nitrite contributes colour and flavour and inhibits C. botulinum; use within legal limits.
- Fish: spoilage produces trimethylamine (TMA) and total volatile basic nitrogen (TVB-N); histamine can form in scombroid fish.
- Eggs: grade by shell, air cell, albumen height (Haugh unit) and yolk index. Pasteurized liquid egg is heat-treated in a way that preserves function.
- Hygiene: cross-contamination from surfaces, hands and utensils is a major risk; separate raw and cooked areas.
Worked example
A 20 kg batch of meat is cured with 2% salt. Salt = 0.02 × 20 = 0.4 kg. If the brine also contains 0.5% sodium nitrite, that is 0.1 kg in the brine, but the legal limit applies to residual nitrite in the finished product, not the amount added. Weigh all ingredients and test the final product.
Traps
Nitrite is not merely a colouring agent; freezing does not kill all microbes; freshness cannot be judged by colour alone; egg shell cracks allow penetration.