Food Processing, Preservation and Packaging Technology
What this domain tests
Preservation principles, standard time-temperature processes, dehydration arithmetic and packaging material regulation. Expect definitions plus one mass-balance or process-selection question.
Thermal processes
- Pasteurisation: LTLT 63 degrees C for 30 minutes; HTST 72 degrees C for 15 seconds; UHT 135–150 degrees C for 1–2 seconds followed by aseptic packaging.
- Canning: commercial sterilisation, 12D concept for low-acid foods; F0 value is lethality referenced to 121 degrees C.
- Blanching inactivates enzymes (peroxidase, catalase) before freezing or drying.
Non-thermal and other methods
- Freezing: blast freezer and individual quick freezing (IQF); slow freezing gives large ice crystals that rupture cells.
- Drying: sun, tray, drum, spray drying for milk and coffee, freeze drying for sensitive products.
- Irradiation: permitted commodity-wise at prescribed doses, labelled as "Irradiated"; also inhibits sprouting in onion and potato.
- Chemical preservatives: benzoic acid for acidic foods, sorbic acid for mould control, sulphur dioxide for colour retention; all with category limits.
Packaging
- FSS (Packaging) Regulations, 2018 govern food-contact materials: virgin or food-grade recycled polymer only, no newspaper for wrapping, no reclaimed plastic for edible oil.
- Modified atmosphere packaging lowers O2 and raises CO2/N2 for respiring produce and meat; vacuum packaging suppresses aerobes but not anaerobes.
- Aseptic packaging pairs sterilised product with sterilised laminate in a sterile zone.
Worked example
100 kg of spinach at 90 per cent moisture is dried to 5 per cent moisture. Dry solids = 10 kg, unchanged. Final mass = 10 / 0.95 = 10.53 kg. Water removed = 89.47 kg. Solids balance is always the short route.
Traps
- Calling UHT milk "sterile" without noting aseptic filling is what preserves it.
- Mixing up pasteurisation time-temperature pairs (63/30 vs 72/15).
- Assuming vacuum packaging prevents all spoilage; C. botulinum risk rises.
- Applying the 12D value to acid foods unnecessarily.