Food Packaging

Course Road-Map & Context

• Position in course: "Food Packaging Dilemma – Shelf Life & Sustainability" (Week 7, Thu 17 July)
  • Preceded by preservation modules from Yong Wang and Ernest.
  • Upcoming: Week 8 “Food & Health” (Jayashree Arkod), Week 9 “Sensory Analysis & Nutrition”, surprise VIP speaker on food security & packaging.
• Lecturer stresses attendance, cross-modular links (food processing, neuroscience, consumer health).
• Exam/quiz hint: lecturer often asks for definitions & formulas.

Why Package? – Dual Perspective

• Two headline functions (quiz cue):
  • Contain the product for transport, portioning, storage.
  • Protect the product from rodents, insects, dirt, oxygen, moisture, light, microbes.
• Additional business/consumer drivers:
  • Marketing & brand communication (printability, shelf appeal).
  • Convenience (willingness to “pay an extra dollar” for easy use, resealability, single-serve).
  • Enable global/non-seasonal supply (e.g., strawberries in winter).
  • Non-uniform distribution/portion control.
• Fundamental dilemma = Protection vs. Environmental waste ➜ “Packaging Dilemma”.

Industry Scale & Milestones

• Australia: > 11\,000\,000\,000 AU$ annual food industry turnover (figure likely higher today).
• Worldwide: ~200\,000\,000\,000 food & beverage containers per year.
• Selected regulatory / sustainability milestones:
  • 1990 DE (Germany): all plastic packaging must be recyclable or combustible.
  • 1995 EU: target 95\% plastic recycling.
  • 1989 Ian Kiernan (AUS yachtsman) launches “Clean Up Australia Day”.
  • Early 2000s: Ellen MacArthur champions Circular Economy.
  • 2005: hottest year on record ➜ climate linkage.
  • 2013: global push that all packaging become recyclable.

Three R’s (Quiz Favourite)

• Reduce (minimise material usage, lightweighting).
• Reuse (returnable bottles, refill systems).
• Recycle (mechanical, chemical, energy recovery).
• Symbol: Möbius loop ♻ — presence ≠ guarantee; depends on consumer compliance & local infrastructure.

Food Groups & Their Specific Packaging Needs

Bakery Goods

• Brittle → require cushioning trays, inner plastic seals to stay crispy (moisture barrier).

Ready-To-Eat (RTE) Breakfast Cereals

• Hygroscopic → waxed or LDPE paper liners inside cardboard; focus on mild moisture & oxygen barrier.

Chocolate & Confectionery

• Solid & fat-rich → paper + aluminium foil to block fat bloom, light & odour.

Dairy

• Sub-types: liquid milk, butter, ice cream, cheese, powders, fermented.
• Hazards: rancidity, bacterial growth, light-induced flavour loss, moisture pickup (powders).
• Solutions: high-barrier laminates, UHT aseptic packs for infant formulas, light-opaque bottles.

Meat & Fish

• Risks: microbial spoilage, oxidation (colour loss), dehydration.
• Solutions: MAP (modified atmosphere), oxygen scavengers, absorbent pads, high-barrier trays.

Savoury Snacks (e.g., potato chips)

• Critical: structural integrity + oxidation of fats.
• Nitrogen flush + cushion space, metallised films.

Fresh Produce

• Continue to respire → semi-permeable films, micro-perforation, breathable clamshells.

Coffee, Dried, Frozen, Alcoholic, Airline Meals

• Coffee: one-way degassing valves, aluminium laminates.
• Frozen: materials must resist -40^\circ\text{C} without embrittlement.
• Alcohol: child-safe, tamper-evident closures, UV barrier for wine/beer.

Core Science: Migration & Barrier Concepts

• Terminology
  • Migration: net movement across package wall (in → out or out → in).
  • Leaching: contaminants leaving package into food (e.g., ink, BPA).
• Typical migrants
  • Water vapour, O2, CO2, ethylene (plant hormone), aroma volatiles, oils.
• Measurement via gravimetric method
  • Place filled pack on ultra-sensitive balance; plot weight Δ vs. time.
  • Regions: adsorption → steady diffusion → saturation.
• Key equation (memorise): \text{WVTR}=\frac{Q}{A\,t}=\frac{P_M\,\Delta P}{d} \quad\left[\frac{\text{g}}{\text{m}^2\,\text{day}}\right]
  • Q = mass of water transferred.
  • A = area; t = time.
  • P_M = permeability constant of film; d = thickness; \Delta P = vapour-pressure diff.
• Higher thickness \uparrow → lower WVTR; laminates can approach near-zero permeability.

Shelf-Life Determination

• Direct storage study (gold standard) – monitor quality until failure.
• Comparative / inferential – benchmark vs. competitor or historical data.
• Shelf Turnover Time – if product sells fast, shorter technical shelf life acceptable.
• Accelerated tests: elevate temperature, humidity or microbial load (“Arrhenius approach”).

Major Packaging Materials

Plastics

• Dominant: consumption > steel; low energy per unit, excellent barriers.
• Common resins: PET (1), HDPE (2), PVC (3), LDPE (4), PP (5), PS (6), “other” (7) – recycling codes inside Möbius loop.
• Manufacturing
  • Extrusion → Blow Molding (hollow bottles; air inflates parison).
  • Extrusion → Injection Molding (tubs, caps; plastic injected into cooled mold cavity).
  • Films & sheets: < 0.1 inch = film; > 0.1 inch = sheet. Used for liners, wrap-around bags.
• Additives & Concerns
  • Plasticisers, antioxidants, colourants → can migrate.
  • Bisphenol A (BPA): endocrine disruptor, binds estrogen receptor; now restricted.
  • PFAS (Per- & Polyfluoroalkyl Substances) “forever chemicals” – persistent, bio-accumulative.
• Environmental fate: fragmentation to micro- (<5 mm) & nano-plastics – detected from ocean trenches to Mt. Everest.

Metals

• Steel/Tinplate
  • Tin layer = sacrificial corrosion barrier & acid protection.
  • Requires prior thermal sterilisation (no survival of microbes in sealed can).
• Aluminium
  • Produced from bauxite electrolytically (energy-intensive; site often chosen by cheap electricity).
  • Virtually non-corrosive, light-weight, infinite recyclability – yet relies on consumer collection.
• Closures: ring-pull, pop-top, stay-on tabs for convenience (consumer pays premium).

Glass

• Chemically inert (except to HF). Historical mass production since \sim350 CE.
• Pros: barrier perfection, quality perception, high-temperature tolerance, endless recyclability.
• Cons: weight, fragility, higher transport emissions; strong PET competition except niche (restaurants want glass).
• Lightweighting: Australian stubby reduced from 260 g (1986) → 170 g (1995).

Paper & Paperboard

• Invented in China (1st century CE). Earliest use for wrapping, sacks \sim17th century.
• Pros: low cost, high print quality, compostable.
• Cons: poor moisture/grease resistance ➜ laminated solutions e.g., Tetra Pak (paper + polymer + Al foil).
• Structural designs: gusseted bags, corrugated (fluted) board, cartons—important for secondary (& tertiary) packaging.

Printing, Design & Marketing

• Product life-cycle ≈ <1 year for “new” design → agility crucial.
• Damage to graphics during palletising can deter consumers.
• Paper easiest to decorate; metals/glass require specialised inks/coatings.

Safety: Tamper Evident / Tamper Proof / Child-Safe

• Historic incidents: Tylenol cyanide poisoning (USA), glass shards in baby food, K pies with cyanide → drove regulation.
• Tamper-evident: irreversible visual damage when opened (heat shrink bands, induction seals).
• Tamper-proof: prevents opening by force (pharma blister packs, break-rings).
• Child-resistant closures: push-down-and-twist, lock-lids.

Closures & Access Systems

• Functions (5-point list): contain, enable first access, allow repeated access, provide evidence of opening, be economical.
• Screw caps, snap-fits, zipper profiles, peelable heat seals.
• Barcode / QR code integration for traceability (computer-readable ID).

Modified Atmosphere Packaging (MAP)

• Goal: inhibit microbial catabolism & oxidative reactions without chemical preservatives.
• Typical gas mixes: CO2 (antimicrobial), N2 (filler, replaces O2), low O2 (<1\%) for fresh meat.
• Components: high-barrier tray + lidding film + absorbent pad (captures purge, may contain antimicrobial agents).
• Shelf-life extension: e.g., fresh steak from ~1 week → ≥3 weeks at 4^\circ\text{C}.
• Snack example: potato-chip bags inflated with N_2 to both cushion & retard oxidation.

Manufacturing Equipment Snapshot

• Extruder parts: hopper (feed), heated barrel, screw, die plate.
• Downstream: cooling rolls, laminators, slitting, pouch form-fill-seal lines.
• Machines must avoid static build-up, crystal breakage in sensitive films.

End-of-Life & Degradation Timelines

• “Plastic and Time”: persists for centuries; UV, heat, abrasion → micro/nano-plastics.
• Intrinsic factors: molecular weight, crystallinity, hydrophobicity, additives.
• Extrinsic: UV exposure, temperature, mechanical stress (e.g., ocean waves).

Ethical & Practical Implications

• Consumers share responsibility: recycling only works if segregation bins used (yellow/red in AU; bottle returns in EU).
• Life-Cycle Assessment (LCA): transport weight of glass vs. PET can shift sustainability ranking.
• Health: migration leads to endocrine disruption (BPA) or PFAS accumulation – driving bans & material innovation.
• Global equity: developing regions lose more food to spoilage (lack of packaging) vs. developed regions lose more to package waste.

Potential Quiz / Exam Prompts (as hinted by lecturer)

• State the two primary functions of food packaging.
• List and explain the 3 R’s.
• Provide the definition and formula for WVTR.
• Compare pros/cons of glass vs. PET for bottled water.
• Outline MAP principle and give two examples (meat, potato chips).
• Identify recycling code for HDPE and give one typical application.
• Explain why BPA is considered an endocrine disruptor.
• Describe blow molding vs. injection molding.
• Name one tamper-evident and one child-safe feature.

Quick Reference Figures & Equations

• Global container usage: 2\times10^{11} units yr$^{-1}$.
• Australian food sector: > 1.1\times10^{10} AU$ per yr.
• WVTR: \text{g}\;\text{H}_2\text{O}\,/\,(\text{m}^2\cdot \text{day}).
• Film classification: film
• Lightweight beer bottle: 260\;\text{g} \rightarrow 170\;\text{g} (1986–1995).

Key Take-Aways

• No “ideal” package: always a trade-off between barrier, cost, weight, recyclability, consumer expectations.
• Understanding migration & barrier science is central to shelf-life design.
• Plastics dominate volume; metals & glass dominate barrier perfection; paper dominates communication & secondary packs.
• Sustainability solutions must pair industry design with consumer behaviour (3 R’s + circular economy).