Topic 5 of 6 · Form 6
Food processing and preservation technology
Destroy or inhibit micro-organisms and enzymes, and prevent recontamination.
Notes for this topic 1 file, in order
Create a free account to download PDFs.
Principles
Destroy or inhibit micro-organisms and enzymes, and prevent recontamination.
Heat processing
- Blanching (inactivates enzymes before freezing or drying).
- Pasteurisation (milk: HTST about 72 °C for 15 seconds) – kills pathogens; product refrigerated.
- Sterilisation and canning (about 121 °C) – commercial sterility; the botulinum cook.
- UHT (about 135–140 °C for a few seconds) – long-life milk.
Low-temperature preservation
Chilling (0–5 °C) and freezing (−18 °C); quick freezing forms small ice crystals and preserves texture.
Drying and water activity
Sun drying (vegetables, fruit, kapenta), solar dryers, spray drying (milk powder), freeze drying; concentration with sugar or salt.
Other methods
Fermentation and pickling (acids lower pH), smoking, chemical preservatives, irradiation, modified atmosphere packaging, vacuum packing.
Cereal and dairy processing
Milling maize (roller meal vs refined super-refined meal – nutrient losses in refining), baking, and processing milk into yoghurt, cheese and amasi.
Packaging
Functions: protect, preserve, inform, market. Materials: glass, metal, paper, plastics; environmental concerns and recycling.
Check yourself
- Why are vegetables blanched before freezing?
- Why is roller meal more nutritious than refined maize meal?
- How does quick freezing preserve texture?
Show answers
- To inactivate enzymes that would cause loss of colour, flavour and nutrients during storage.
- It retains more of the germ and bran, keeping more fibre, B vitamins and minerals.
- It forms small ice crystals that cause less damage to cell walls.
Questions about this topic (0)
No questions about this topic yet.
Sign in or create a free account to join in.