Week 1: Introduction to Food packaging - Coggle Diagram
Week 1: Introduction to Food packaging
Functions of Food Packaging :check:
Protection ~ Primary function to protect against external factors such as water, gas, odours, m/o & dust
Communication ~ act as a “silent salesman”, fulfil mandatory requirement (allergens declaration, NIP) or provide usage instruction . Barcode & RFID tags in warehouse & supply chain
Containment ~ Prevent leakage of contents to avoid product loss & pollution
Convenience ~ pre-prepared foods that can be cook/re-heat easily, re-sealability, easy to hold/pour/open features, building into secondary/tertiary packages
Different Levels of Food Packaging :check:
Tertiary (eg Pallets)
Secondary: Packs the primary packaging
Quaternary (eg Shipping containers)
Primary: direct contact with food products
Common Packaging Material Used in Food Industry
4 Food Packaging Materials
Plastic: Made from Macromolecular organic polymers from low molecular weight (Mw) molecules
Properties, including barrier properties, depend on the chemical nature
(EG molecular structure, Mw, degree of crystallinity & chemical composition)
Polyamides (aka Nylon which is a brand name)
highly permeable to water vapour
due to amide group (polar)
Low permeability to gas if film is dry.
Excellent thermo-formabilty, flex-crack resistance and mechanical strength up to 200℃
Widely used in vacuum packaging of processed meats and cheese
with other material e.g. LPDE for
heat sealability and moisture barrier.
Plasticized (add plasticisers, something elastic), thin, PC film: with high water vapour permeability
used for stretch wrapping of expanded polystyrene trays for fresh produce/meat
Unplasticized, rigid PVC sheet::
better in oil resistance and barrier property than HDPE
but softened by solvents.
used as inserts for chocolate boxes.
PVdC: Homopolymer (one type), stiff film that is not suitable for packaging
(therefore, + 20% of vinvyl chloride ) Copolymers: a soft, tough and relatively impermeable film.
good odour, gas, water vapour barrier property.
(Ethylene vinyl alcohol) EVOH
superior barriers to gas, odour, solvent, fragrance esp. when dry.
However, gas barrier property can be affected by moisture (OH groups dissociates in water).
As barrier layer: used in plastic containers to replace glass and metal containers.
Usually linked to polyolefins (with excellent moisture barrier)
Crystal grade: gives metallic sound with high refractive index but
poor barrier to gas & water vapour
Used in fresh produce
Extruded & Expanded PS: foam sheet widely used in disposable packages or dinnerware.
Polyethylene terephthalate (PET)
Great tensile strength and chemical resistance
Stable over huge temperature range (-60 to 220 ℃).
As bottles: stretch blow moulded or biaxial orientated for
maximum tensile strength and gas barrier
(suitable for carbonated drinks)
To be economical, reduce the weight with desired strength
Polycarbonate (PC): excellent high temperature resistance, high impact strength and clarity.
Can be used in ovenable trays for frozen foods to enhance low temperature impact strength.
Blow and injected moulded: used in reusable bottles due to its clarity and strength and resistance to staining by tea/coffee/tomato sauces etc. However, it has BPA that raises consumer concern
Polyolefins: type of polymer produced from a simple olefin (aka alkene) as a monomer
LDPE: Many short side chains that prevent close packing (like amylopectin)
Tough, flexible, slightly translucent material.
Easy to seal
Good barrier to water vapour but
poor gas barrier properties
HDPE : More linear structure but stiffer and harder. (like amylose)
Provides good oil/grease resistance.
Appear as white, translucent film or rigid bottles
Poor gas barrier properties
with lower density, higher softening point (Under high temp, they start to melt) and
better barrier properties
Compatible with most foods.
strong, rigid and chemically inert with excellent barrier against solids, liquids and gases
does not deteriorate appreciably with age
Excellent product visibility from clear glass
Can add colorant to give amber or green glass :
extremely versatile to size & shape
Jars: wide opening to enable hand/spoon to dip in
Bottles: narrow necks to control flow of fluid
Limitation: heavy and fragile during transportation
Paper: Produced from pulp which is obtained plant
Paper greater than 224 gsm or g/m2 is known as paperboard. Corrugated board is made from a combination of two sheets of paper (liners) glued to a corrugated inner medium called fluting
Poor barrier against gases and water vapour but can be laminated or coated with plastic polymers to improve the barrier properties
E.g. paraffin wax coated paper cup
E.g. PET coated paperboard in dual oven-able trays
4 common metals are used in food packaging namely : steel, aluminium, tin and chromium
Aluminium: Usually used In form of purified alloys containing small and carefully controlled magnesium and manganese.
Aluminium for metal cans and foil ranged 4-150 𝜇m.
If foil thickness is thicker than 15 𝜇m it is impermeable to gases and water vapour.
NOT PACKED WITH brine solution that can cause corrosion
lighter and more ductile but weaker than tinplate & ECCS
Tin gives good strength and fabrication qualities with corrosion resistant surface
Electrolytically Chromium Coated Steel (ECCS): Chromium are electrolytically applied/coated to steel base respectively
Chromium coating generally thinner than tin coating & needs lacquering (protective coating)
Lghter but less resistant to corrosion compared to tinplate
Uses Protective coating (internal & external)
Protects the metal from foods
Acts as barrier against external corrosion esp. seam region
Serves as basis for decoration
Usually use Epoxy resins, including those with Bis-phenol A (BPA) that consumers are concern about.
PET coating serving
(involves) Vacuum metallization: Produce metallized films by thermal evaporation of metals (e.g. aluminium) in vacuum and physical vapour deposition (PVD)
3 types :check:
Semi-rigid: neither rigid nor flexible in nature. Some part of packaging can change its shape readily
EG Stand up pouch
Rigid: Shape is not readily changed
Flexible: any package or any part of a package whose shape can be readily changed.