Food Plant Equipment and Laboratory Practice
Food Plant Equipment and Laboratory Practice
This domain tests correct use of equipment, calibration, sampling and safety in food plants and labs.
Core rules
- Sterilization: autoclave uses saturated steam under pressure (typically 121 °C, 15 min); hot-air oven uses dry heat (160–170 °C, 2 h) for glassware, not liquids.
- Analysis: moisture by oven, ash by muffle furnace, fat by Soxhlet, protein by Kjeldahl, pH by calibrated meter, TSS by refractometer.
- Calibration: balance, thermometer, pH meter and refractometer must be checked against standards; record results.
- Sampling: use clean, sterile containers; take representative samples; label with date, batch and time; maintain cold chain.
- Safety: PPE, fume hood for solvents, no mouth pipetting, electrical safety and proper chemical waste disposal.
Worked example
A 1.000 g food sample gives 0.032 g nitrogen by Kjeldahl. %N = 0.032 ÷ 1.000 × 100 = 3.2%. Using the 6.25 factor for protein: %protein = 3.2 × 6.25 = 20.0%. A blank titration is subtracted first; using the wrong factor gives a biased result.
Traps
Autoclave and hot-air oven are not interchangeable; a pH meter needs buffer calibration; unlabelled samples are invalid; do not pipette by mouth.