Food Packaging: Shelf-Life, Materials & Sustainability

These flashcards cover key points from the lecture on food packaging, including purposes, sustainability issues, materials (plastics, metal, glass, paper), migration theory, shelf-life, modified atmosphere packaging, regulatory and safety aspects, and environmental considerations.

What are the two primary functions of food packaging?

To protect the product and to contain the product for transport and storage.

Name the three Rs of sustainable packaging.

Reuse, Reduce, Recycle.

Why is food packaging described as a "dilemma"?

Because it extends shelf-life and reduces food waste, yet generates large amounts of environmental waste.

What single word describes the main performance requirement of any package toward gases, vapours or solutes?

Barrier.

Define migration in the context of food packaging.

The movement of substances across the package boundary, either from outside in or from inside out.

What term is used when packaging components move into the food product?

Leaching.

Write the unit for Water Vapour Transmission Rate (WVTR).

Grams of water per square metre of film per day (g · m⁻² · day⁻¹).

How does increasing film thickness affect WVTR?

It reduces WVTR because diffusion path length is longer.

Name two key gases controlled in Modified Atmosphere Packaging (MAP).

Oxygen (O₂) and Carbon Dioxide (CO₂) (nitrogen is also common).

What is the main purpose of MAP for fresh meat and fish?

To slow microbial growth and extend shelf-life without chemical preservatives.

Why are potato-chip bags filled with gas?

To create a cushion (MAP) that prevents breakage of brittle chips during transport.

Give one convenience-related reason consumers accept higher prices for packaged foods.

Packaging enables ready-to-eat, portioned, or easy-to-open products that save time.

Which packaging material is described as chemically inert but heavy and fragile?

Glass.

What is the Mobius loop symbol used for?

To indicate that a plastic item is recyclable and identify its resin code (1–7).

Which resin code corresponds to PET (polyethylene terephthalate)?

1

List two additives that may be blended into plastics and their purpose.

Plasticisers (increase flexibility) and antioxidants (prevent oxidation of the food or polymer).

Why has Bisphenol-A (BPA) been restricted in food packaging?

It can leach into food and act as an endocrine disruptor, mimicking hormones.

State one environmental hazard associated with plastic bags.

They can float in waterways, suffocate wildlife, and fragment into microplastics.

What is blow-moulding used to produce?

Hollow plastic containers such as bottles by inflating molten plastic inside a mould.

Explain how extrusion works in film production.

Plastic pellets are melted and forced through a die plate by a screw, forming continuous film or sheet.

Why are multilayer (laminated) films used?

To combine outer printability, middle strength, and inner food-contact barrier into one package.

What metal is most widely used for beverage cans because it is light and non-rusting?

Aluminium.

Why is tin plated onto steel cans?

To provide sacrificial corrosion protection and create an acid-resistant barrier.

State one advantage and one disadvantage of glass packaging.

Advantage: Chemically inert and fully recyclable. Disadvantage: Heavy and brittle.

What packaging innovation cut beer-bottle weight nearly in half between 1986 and 1994?

Light-weighting of glass through improved design and processing.

Why is paper considered the "printer’s dream" material?

It accepts high-quality, low-cost printing for branding and information.

What composite carton uses laminated paper, plastic and often aluminium to package liquids?

Tetra Pak (aseptic carton).

Define secondary packaging and give an example.

A layer that groups primary packages for distribution; e.g., a corrugated box holding 24 cans.

Name two methods for determining product shelf-life.

Direct observation/storage test and accelerated shelf-life testing (e.g., elevated temperature).

How can thermal processing and hermetic sealing extend shelf-life in metal cans?

By killing microorganisms before sealing and preventing re-entry of contaminants.

What is tamper-evident packaging?

A closure system that leaves visible damage if opened or interfered with (e.g., safety button lids).

Why must pharmaceutical and some food packages be child-resistant?

To prevent accidental ingestion of harmful substances by children.

Give one example of a closure type that allows repeated resealing.

Screw-cap, zip-lock, or press-on plastic lid.

Explain the term "shelf turnover time".

The average time it takes for a product to be purchased off the retail shelf.

Which intrinsic polymer property generally increases resistance to diffusion?

Higher crystallinity or higher molecular weight.

What is a common polymer used for stretch/shrink wraps on pallets?

Low-density polyethylene (LDPE).

Why can glass be recycled indefinitely without loss of quality?

Because it can be remelted and re-formed without degrading its chemical structure.

What biodegradable protein from milk was once used to make early plastics?

Casein.

State one reason ethylene gas levels are important in fresh-produce packaging.

Ethylene accelerates ripening; controlling its migration extends produce shelf-life.

Which global initiatives by sailors Ian Kiernan and Dame Ellen MacArthur relate to packaging waste?

Clean Up Australia Day (Kiernan) and the Circular Economy Foundation (MacArthur).