Packaging, Storage and Transport of Processed Foods
Functions and materials
Packaging contains, protects, preserves, informs and sells. Selection depends on sensitivity to moisture, oxygen, light and mechanical shock, plus intended shelf life and distribution.
- Glass: inert, excellent barrier, transparent, but heavy and fragile.
- Metal cans: tinplate with internal lacquer; strong and retortable, but can corrode with acidic foods.
- Paper and board: cheap and printable, poor moisture and grease barrier unless coated or laminated.
- Plastics: PE gives a good moisture barrier but poor oxygen barrier; PP suits hot fill and retort; PET for carbonated drinks and oil; PS for dairy cups; PVC for cling film. Laminates combine layers to achieve the required OTR and WVTR.
- Aseptic cartons: paperboard, polyethylene and aluminium, giving ambient shelf life to UHT milk and juice.
Storage and transport
Cold-chain integrity is the main exam theme: pre-cooling, cold stores at 0–4 °C for perishables, −18 °C for frozen foods, controlled atmosphere for apples, and dry stores below 25 °C and 60% RH for flour and biscuits. Follow FIFO and FEFO, keep pallets off the floor and away from walls, and monitor temperature with data loggers. Reefers need air-circulation space; never block the evaporator.
Worked example
Potato chips need a moisture barrier and oxygen or nitrogen flush. A metallised PET/PE laminate gives low OTR (about 1 cc/m²/day) and low WVTR; a plain paper bag would let moisture in within days and make chips soggy. Reasoning: crispness is the critical quality attribute, so WVTR dominates the choice, while light barrier protects against rancidity.
Traps
Confusing OTR (oxygen) with WVTR (water vapour); using PVC for hot filling; forgetting light barrier for milk; overloading pallets beyond stack strength; treating best-before as a safety date; ignoring FSSAI food-contact and migration rules.