11 Flashcards
Packaging in general
Ancillary sector allied with food industry. Consumes 50% of packaging material. Major contributor to cost because often costs more than product. Filling/forming/closing require special machinery.
Classification of packaging
Primary: direct contact with food (plastic bags, cans)
Secondary: rigidity, printing or grouping products into larger unit (cardboard box, corrugated box)
Tertiary: Same role with respect to secondary packaging (pallet to hold a set number of boxes)
OR
Rigid (cans, jars, best protection but lot of space), semi rigid (squeeze bottle/tetra brick, combination of both flexible into semi-rigid, form-fill seal), flexible (retort pouch, plastic bags, reduces warehousing costs)
Other forms of packaging
Plastic bottles, form trays are made by blow-molding on site
Hermetic package
Hermetic package is impermeable to gases and vapors. Cans and bottles meet these requirements as does tetra brick. Many flexible packages are semi-permeable to gases and susceptible to pinholes. Exceptions is the retort pouch
Tin cans
Tin can was originally made of steel with a thin coating of tin to prevent rusting. Tin (expensive) has been replaced by other metallic coatings or corrosion-resistant steels alloys are used. Epoxy resins used as internal coatings for acidic and other corrosive food products that protects integrity of can and prevents contamination of contents by dissolved metals. Epoxy resins are commonly made of Bisphenol A (BPA). 1000cans/min, seal with 5metal folds and epoxy. 3-pieces or 2-pieces(steel but more common in aluminum cans. Strength is important because has to survive retort pressure changes hence ribbing on cans.
Aluminum
Light, resistant to atmospheric corrosion, malleable. Lower structural strength than steel. Needs internal pressure to maintain strength (beers, softdrinks). Convenience-pull tab. Aluminum foil is used in other packaging material as laminate to provide gas/vapor barrier (retort pouch). Economical to recycle
Glass
Chemically inert and transparent, but heavy and fragile. Can be strengten by adding coating to glass. Made from sand, soda ash, limestone heated to 1500C and blow mold. Susceptible to mechanical and thermal shock (in retort) but microwaveable.
Paper
Coated and waxed to prevent loss of strength due to moisture ingression. Has to meet food-grade microbial standards
Plastic and films
Predominate. 20 thermoplastic polymers are used. Can be produced as heteropolymers or homopolymers. Polymers can also be co-extruded to form laminates to combine properties. Can have specific moisture and gas permeability with selective permeability (water, o2, h2o)
To choose a film:thickness, clarity, temperature, resistance to sunlight, gas/vapor permeability. Types of films: regenerated cellulose (cellophane), polyamide(nylon), polyester resin (mylar), polyethylene (saran wrap, originally from pvc)
Retort pouch and trays
=flexible can, tetra laminate:
1.polypropylene food compatibility and sealing.
2.aluminum foil for hermetic barrier
3.nylon for resistance to abrasion-tough
4.polyester for heat resistance and printability
Military applications but slow filling rate and high cost of package. Retort thermo-formed trays are convenient for convenience food presentation (peel foil and microwave)
Edible coatings and films
Casings for wieners, sausages are made of collagen, animal intestines, cellulose or plastic. Confectioner’s glaze is made of sugar coatings. Starch coating for raisins reduce moisture release. Starch polymers for premixed food ingredients and the package dissolves.
Special feature packaging
Mylar (polyester) or nylon for heat resistant and moisture retaining product for boil in the bag
Aerosol
Nitrous oxide (n2o)
Pet bottles
Polyethylene terephthalate clarity, low weight and no breakage
MAP
Modified atmosphere packaging Impermeable to gases.
