Practical Skills, Laboratory and Workplace Safety
12. Practical Skills, Laboratory and Workplace Safety
This domain tests safe and accurate work in the food processing lab and plant. Expect questions on glassware, moisture/ash determination, titration, microbial plating, PPE and emergency procedures.
Core rules
- PPE: lab coat, gloves, safety goggles and closed shoes; tie back hair; no eating or drinking in the lab.
- Read the label and SDS before using a chemical; add acid to water, never water to acid; use a fume hood for volatile reagents.
- Weigh accurately after taring; cool crucibles in a desiccator before weighing; record all readings.
- Moisture: weigh sample, dry to constant weight, cool in desiccator, reweigh. Ash: incinerate at controlled high temperature.
- Microbiology: sterilise media and glassware in an autoclave; work near a flame or in a laminar flow; do not open plates unnecessarily.
- Plant safety: machine guards, lockout-tagout, dry floors, fire extinguisher, first-aid box and clear exits.
Worked example
A 5.000 g sample is dried and reweighed at 4.500 g. Moisture = (5.000 − 4.500) ÷ 5.000 × 100 = 10.0%. Reasoning: the loss in mass is moisture; divide by the original sample mass, not the final mass.
Traps
Do not weigh hot crucibles; they gain mass as they cool and absorb moisture. Do not mouth-pipette. Autoclave tape is not proof of sterility by itself. Never use water on an electrical fire.