Quality Assurance, Testing and Waste Management
Quality assurance builds confidence that food meets specifications, while quality control performs the tests. The exam tests sampling, calibration, proximate analysis, rapid tests, record keeping, effluent parameters and waste management.
Core rules
- QA is process-focused and preventive; QC is product-focused and inspection-based.
- A representative sample must be collected, labelled and handled without contamination. Composite samples are used where appropriate.
- Instruments such as pH meters, balances and thermometers must be calibrated against traceable standards.
- Common tests include moisture, ash, fat, protein, pH, acidity, total soluble solids and microbial counts.
- BOD measures oxygen consumed by microorganisms; COD measures oxygen demand of chemical oxidation. COD is usually higher and faster to measure.
- Waste management follows the hierarchy: prevent, reduce, reuse, recycle, recover and dispose.
Worked example
A 5 mL effluent sample is diluted to 300 mL. The dissolved oxygen drop is 4 mg/L. BOD = 4 × (300 ÷ 5) = 240 mg/L. The reasoning multiplies the measured oxygen drop by the dilution factor.
Traps
- Treating QA and QC as identical.
- Using an uncalibrated pH meter.
- Confusing BOD with COD.
- Collecting a non-representative sample.
- Sending untreated high-strength effluent to land or drains.