Packaging MaterialsPackaging Materials

An overviewAn overview

Main Packaging Main Packaging MaterialsMaterials

MetalsMetals Paper and BoardPaper and Board GlassGlass PolymersPolymers

This session will concentrate on the first threeThis session will concentrate on the first three

MetalsMetals

Metals are elements which generally share a Metals are elements which generally share a range of properties to a greater or lesser range of properties to a greater or lesser degree includingdegree including StrengthStrength MalleabilityMalleability DuctilityDuctility Metallic “sheen”Metallic “sheen” Conduct electricityConduct electricity

Metals (2)Metals (2)

The metals most widely used with foods areThe metals most widely used with foods are SteelSteel

Usually found in the form of tinplateUsually found in the form of tinplate AluminiumAluminium

SteelSteel

Steel is an alloy of iron & carbon plus small quantities of Steel is an alloy of iron & carbon plus small quantities of other metalsother metals

Its advantages are its Its advantages are its strength,strength, malleability and ductilitymalleability and ductility

Carbon steel is relatively easily corroded, so for food it is Carbon steel is relatively easily corroded, so for food it is usually coated with tin (tinplate)usually coated with tin (tinplate)

The major use of tinplate is for canning - a process which The major use of tinplate is for canning - a process which has been in use for about 200 years.has been in use for about 200 years.

AluminiumAluminium

Aluminium is a soft white metal which is less Aluminium is a soft white metal which is less dense, but more corrosion resistant than steel.dense, but more corrosion resistant than steel.

For food applications aluminium is usually For food applications aluminium is usually alloyed with up to about 4% other elements to alloyed with up to about 4% other elements to give it more strength.give it more strength.

Aluminium is used for three major food Aluminium is used for three major food applicationsapplications BeverageBeverage canscans Foil containersFoil containers Aerosol cansAerosol cans

Can manufactureCan manufacture

Cans are produced in two major formsCans are produced in two major forms Three piece with rolled and soldered side seams and Three piece with rolled and soldered side seams and

two separate end enclosurestwo separate end enclosures Two piece in which sides and one end are formed from Two piece in which sides and one end are formed from

flat sheet and are seamless. There is only one end flat sheet and are seamless. There is only one end enclosure.enclosure.

The ends are sealed by a double seal which is purely The ends are sealed by a double seal which is purely mechanicalmechanical

The interior of cans is usually coated with a suitable The interior of cans is usually coated with a suitable “enamel” to protect against tainting the food.“enamel” to protect against tainting the food.

GlassGlass

Glass results from the fusing together of oxides of Glass results from the fusing together of oxides of silicon, sodium and calcium to form a hard, brittle, silicon, sodium and calcium to form a hard, brittle, clear material.clear material.

It is neither truly solid, nor truly liquid, but is It is neither truly solid, nor truly liquid, but is referred to as a “vitreous” material.referred to as a “vitreous” material.

Small quantities of oxides of other elements can Small quantities of oxides of other elements can be added to the glass mix to vary the properties of be added to the glass mix to vary the properties of the glassthe glass

Properties of glassProperties of glass

Glass is a hard brittle material which is easily Glass is a hard brittle material which is easily shattered by a sharp blow.shattered by a sharp blow.

Sudden heating and cooling (thermal shock) can Sudden heating and cooling (thermal shock) can cause glass to crack, though grades of glass with cause glass to crack, though grades of glass with improved heat resistance are available (e.g. improved heat resistance are available (e.g. borosilicate glass)borosilicate glass)

It is widely compatible with foodsIt is widely compatible with foods It can be cleaned and re-used and also recycled.It can be cleaned and re-used and also recycled.

Paper and boardPaper and board

Paper is produced by separating then re-bonding vegetable Paper is produced by separating then re-bonding vegetable fibres (mainly cellulose)fibres (mainly cellulose)

Vegetable materials (mainly wood pulp) are treated Vegetable materials (mainly wood pulp) are treated chemically to form a pulpchemically to form a pulp

A dilute solution of the pulp is filtered through a wire A dilute solution of the pulp is filtered through a wire mesh to produce the basic papermesh to produce the basic paper

This is then hot pressed and dried to produce paper.This is then hot pressed and dried to produce paper. Various finishes are then applied to produce the desired Various finishes are then applied to produce the desired

grades of papergrades of paper

Grades of paperGrades of paper

Kraft paper; a strong paper often used for paper sacksKraft paper; a strong paper often used for paper sacks Vegetable parchment; a paper specially treated with acid to Vegetable parchment; a paper specially treated with acid to

give it a closer, smoother texturegive it a closer, smoother texture Sulphite paper; a lighter, weaker paper than kraft paper - Sulphite paper; a lighter, weaker paper than kraft paper -

often used as paper bags and sweet wrappersoften used as paper bags and sweet wrappers Greasproof paper; produced from sulphite pulp where the Greasproof paper; produced from sulphite pulp where the

fibres are more thoroughly beaten to give a closer texture. fibres are more thoroughly beaten to give a closer texture. It is resistant to oil and greaseIt is resistant to oil and grease

Tissue; is a soft resilient paper used for protection.Tissue; is a soft resilient paper used for protection.

Properties of paperProperties of paper

Of moderate mechanical strengthOf moderate mechanical strength Loses its strength when wetLoses its strength when wet Can easily be folded and laminated to produce Can easily be folded and laminated to produce

stronger structuresstronger structures Can be coated, e.g. with wax to produce water Can be coated, e.g. with wax to produce water

resistance for liquid containersresistance for liquid containers Low cost, light weight, flexible and recyclableLow cost, light weight, flexible and recyclable

Aseptic packagingAseptic packaging

Aseptic packaging is a process where the food is Aseptic packaging is a process where the food is sterilised then filled into sterile containers under sterilised then filled into sterile containers under conditions which will prevent recontamination.conditions which will prevent recontamination.

It differs from in-pack sterilisation in that the It differs from in-pack sterilisation in that the containers and food are sterilised separatelycontainers and food are sterilised separately

This enables HTST processes to be used as the This enables HTST processes to be used as the centre of the packaging does not have to be heated centre of the packaging does not have to be heated to sterilisation temperature.to sterilisation temperature.

Aseptic processing (2)Aseptic processing (2)

The shorter processing times possible mean the food is less The shorter processing times possible mean the food is less processed leading to less destruction of vitamins and loss processed leading to less destruction of vitamins and loss of flavours.of flavours.

Because the packaging does not have to be heated, a wider Because the packaging does not have to be heated, a wider range of packaging is availablerange of packaging is available

However, care must be taken to ensure sterility during the However, care must be taken to ensure sterility during the packaging operationpackaging operation

Aseptic processing permits longer shelf life at normal Aseptic processing permits longer shelf life at normal temperatures with higher quality productstemperatures with higher quality products

The EndThe End