Raw material science: meat, poultry, seafood, dairy, produce and dry goods
Scope
This domain tests the science behind receiving, storing and preparing meat, poultry, seafood, dairy, produce and dry goods in a Western production kitchen. Questions link intrinsic properties-pH, water activity, fat composition, respiration rate-to handling, shelf-life and processing decisions.
Core rules
- Post-mortem muscle undergoes glycolysis, pH fall, rigor mortis and resolution. Beef typically needs 7–14 days at 0–2 °C to tenderise; fish rigor resolves within 1–3 days.
- Collagen converts to gelatin with moist heat at roughly 70–90 °C; elastin resists. This explains why shin needs braising and fillet does not.
- Myoglobin states: oxymyoglobin (bright red), deoxymyoglobin (purple), metmyoglobin (brown). Brown colour is not proof of spoilage.
- Scombroid fish can form histamine; cooking does not destroy it. Parasite control for wild fish requires freezing at -20 °C for at least 24 h or -35 °C for 15 h.
- Dairy: pasteurisation reduces pathogens but does not sterilise; fat content changes whipping and melting.
- Produce: respiration and ethylene drive deterioration. Separate ethylene producers (apples, bananas) from sensitive items (leafy greens, cucumbers).
- Dry goods: water activity below 0.6 suppresses most microbial growth; oxidation and pests remain risks.
Worked example
Two beef loins arrive: loin A pH 5.5, loin B pH 6.2. Loin B is darker, firmer and has higher water-holding capacity but shorter shelf-life and greater spoilage risk. Use B for immediate roasting or further processing, not long wet-ageing. Loin A is suitable for ageing and raw sale.
Traps
- Believing frozen fish removes all parasite risk without a validated time-temperature schedule.
- Treating brown metmyoglobin as a definite spoilage marker.
- Storing ethylene producers with ethylene-sensitive produce.
- Using pH alone to judge freshness; temperature history and sensory checks are also required.