•Packaging sector represents 2% of the gross national production developed countries.

•Packaging is defined as a socio-scientific discipline that operates in society to ensure thedelivery of goods to the ultimate consumer in the best condition intended for their use(Lockhart 1997)

•The word ‘package’ means the physical entity that contains the product.‘Packing’ can bedefined as the enclosing of an individual item(or items) in a package or container.

•Levels of packaging:-

A.) Primary package(direct contact with the food)

B.)Secondary package(contains number of primary packages, e.g. corrugated case or boxetc.)

•Functions of packaging:-

a.)Containment

b.)Protection

c.)Convenience

d.)Communication

•Packaging environments:- Packaging performs its functions in three environments

a.)Physical environment (includes shocks, drops, falls etc.)

b.)Ambient environment (surrounds the package)

c.) Human environment ( package interacts with the people)

2. Structure and Properties of Plastic Polymers

The word plastic has been derived from Greek Plastikos meaning easily shaped or deformed.

Properties of plastics are determined by :-

1.)Chemical and physical nature of the polymers

2.) Molecular structure and weight of polymers

3.)Degree of crystallinity

Different additives are added to obtain better products such as, plasticizers(e.g. DOP,DOA etc.),antiaging additives, surface property modifiers etc.

Classification of polymers on different basis:-

(A)Chemical composition (B) Molecular structure

Homopolymers Heteropolymers Linear polymers Branched/Cross-linked

(C) Polymerization process (D) Heating properties

Addition Condensation Thermoplastics Thermosetting plastics

Example of plastic polymers:- Polyolefins(LDPE,HDPE,LLDPE), Polypropylene, Polyethylene, Polystyrene, Polyvinyl Chloride, Polyesters, Polycarbonates, Polyamides,

3. Edible, Bio-based and Biodegradable Food Packaging Materials

Edible packaging consists of edible films, sheets, coatings and pouches which canbe consumed with the packaged product.

Functions:

A.)Selective barrier to retard the migration of moisture

B.)Gas transport

C.)Oil and fat migration and Solute transport

D.)Improve the mechanical handling properties

E.) Retain volatile flavour compounds Edible film

F.)Carry additives such as anti-oxidants and antimicrobials

Example: Polysaccharides, Starch, Cellulose, Hemicellulose, Chitosan, Gums, Lipids,Proteins etc.

Biobased packaging material:-These are made from renewable raw materials and canbe classified according to their origin and method of production such as, polymersdirectly extracted from biomass such as starch, cellulose, polymers produced byclassical chemical synthesis, or naturally or genetically modified organisms etc.

Biodegradable plastics:-It is a degradable plastic in which the degradation processresults in lower MW fragments produced by the action of naturally occurring micro-organisms such as bacteria, fungi and algae. Example:-Starch, polylactic acid,polyhydroxyalkanoates, polycaprolactone etc.

4. Properties of Thermoplastic Polymers

Optical properties

These are related to both the degree of crystallinity and actual polymer structure.

These include- clarity, haze, colour, transmittance, reflectance, gloss and refractive

index.

Tensile Properties

These include- tensile and yield strength, elongation and Young’s modulus.

Bursting strength, Impact strength, Tear strength, Stiffness, Crease or flex resistance,

Coefficients of friction, Blocking and Orientation and shrinkage are also included in

tensile properties.

Barrier properties

The barrier properties of plastics indicate their resistance to sorption and diffusion

of substances such as gases and flavour and aroma compounds.

The term sorption is generally used to describe the initial penetration and dispersal

of important molecules into the polymer matrix and includes both adsorption and

absorption as well as cluster formation.

5. Processing and Converting of Thermoplastic Polymers

(A) Extrusion:-

It is the most important plastics processing methods in use today.

It can be defined as continuously forcing a molten material through a shaping

device.

It includes monolayer extrusion and coextrusion

The screw is the heart of extruder

(B) Calendaring:-

It is a complementary process to film and sheet extrusion and involves the

formation of continuous sheets of evolved thickness by squeezing a heated plastic

material between two or more horizontal rollers.

Contd…

(C) Coating and Laminating:-

Coating and laminating are two of the most widely used processes for transformingflexible films and sheets into products having properties useful in food packaging.

Coating is the process of applying one or more layers of a fluid or melt to thesurface of a material, while laminating is the bonding of two or more webs.

(D) Blending:-

Polymer blending is a low-cost alternative route to multilayer extrusion.

(E) Vapor Deposition:-

It is a general term used to describe any of a variety of methods to deposit thin filmsby the condensation of a vaporized form of the material onto various surfaces.

(F) Orientation:-

It is a means of improving their strength and durability in order to broaden theirscope of application and make them serviceable in thinner gauges.

It involves the stretching the material in such a manner so as to line up themolecular chains in a predetermined direction.

(G) Cross-Linking:-

It interferes with molecular packing, reduces the level of crystallization and,consequently, results in a polymer with a low hardness and yield strength.

(H) Thermoforming:-

A sheet of thermoplastic material is heated to its softening temperature, usually bymeans of an infrared radiant panel heater.

6.Paper and paper-based packaging materials

Pulp:

It is the fibrous raw material for the production of paper, paperboard, corrugated

board and similar manufactured products.

About 97% of the world’s paper and board is made from wood pulp and 85% of the

wood pulp used is from spruces, firs and pines.

Wood pulp contains mainly cellulose, hemicellulose and lignin.

Paper:-

Paper derives its name from the reedy plant papyrus.

Most properties of paper depend on direction

Paper is divided into two broad categories: fine papers( typically used for writing

paper,bond,l edger, book) and coarse papers (used for packaging).

Different types of paper include- kraft paper, bleached paper, greaseproof paper,

glassine paper, waxed paper and vegetable parchment paper.

Paperboard:

Paper is generally termed board when its grammage exceeds 250gsm.

Folding cartons are made from sheets of paperboard which have been cut and

scored for bending into desired shapes.

7. Metal Packaging Materials

Four metals commonly used for the packaging of foods are- steel, aluminium. tin

and chromium

(A)Tinplate: It refers to low-carbon, mild steel sheet varying in thickness.

Manufacture of pig iron

Steelmaking

Tinplating

(B)Aluminium: It is the Earth’s most abundant metallic constituent. It is a lighter,

weaker but more ductile material that cannot be soldered. It is used for the

manufacture of containers, foils. Retort pouches, tubes and bottles.

(C) ECCS: Electrolytic chromium/chromium-oxide-coated low-carbon steel sheet

It is prepared by electrotinning. It consists of a duplex coating of metallic

chromium and chromium sesquioxide.

8. Glass Packaging Materials

Glass is “an amorphous , inorganic product of fusion that has been cooled to a rigid

condition without crystallising”.

The two main types of glass container used in food packaging include-

bottles(which have narrow necks) and jars (which have wide openings).

Principal ingredient- silica

Manufacture process:

Mixing and Melting

Forming process

Blow & Blow process

Annealing

Surface treatment

9.Printing and Labelling process of Packaging Materials

Basic principle of printing-Ink is deposited on an engraved plate and the inked

image is transferred to the substrate through contact.

Different methods of package printing :-

a.) Conventional methods of printing (relief, letterpress, flexography and flexo process)

b.) Gravure/intaglio (more commonly known as rotogravure printing)

c.) Lithography (offset lithography/ planographic printing)

d.) Screen printing ( stenciling process)

e.) Digital printing methods (printing from a digital source)

f.) Electrophotography ( oldest nonimpact printing technology).

Labeling is a means of performing the communication function of packaging,

informing the consumer about nutritional component, net weight, product use and so

on. It includes various labels such as- glued-on labels, self-adhesive labels, in-mold

labels, sleeve labels holographic labels etc.

Coding includes a “closed” code on the packaged product such as bar code which is

defined as a series of parallel bars and spaces arranged according to the encodation

rules of a particular specification in order to represent the data.

10. Food Packaging Closures and Sealing Systems

Closures mainly consist of cap, lid or cork to seal the jar or bottles.

Functions:

1.)Provide hermetic seal

2.) Provide easy opening

3.) Provide evidence of inviolability.

Closures are made from either metal or plastic

For closures either heat or cold sealing is done.

Heat sealing involves welding thermoplastic polymer surfaces together in order to produceseals or joints of sufficient strength to withstand stresses.

Cold sealing is done for the packing of heat-sensitive foods such as chocolate, chocolate-coated biscuits, ice-creams etc.

Peelable seal technology provides retention of package integrity and also allows consumers toaccess the contents without tearing or destroying the package.

Plastic closures Easy open ends(EOE) Metal closure

11. Deteriorative Reactions in Foods

Deteriorative reactions in food

Enzymic reactions Chemical reactions Physical changes Biological changes

Sensory quality Caking

Nutritional quality

Microbiological Macrobiological

Factors controlling the rates of deteriorative reactions in foods

Intrinsic factors Extrinsic factors

Water activity Temperature

Oxidation-reduction potential Gas atmosphere

Light

12. Shelf Life of Foods

The finite length of time from production to unacceptability is referred to as shelf life.

Shelf-life determination is required:

a.) To determine the shelf-life

b.)To study the effect of specific factors

c.) To determine the shelf life of prototype.

Shelf-life can be determined from two sides:- product side or consumer side.

Determination from product side includes sensory evaluation or combination with

instrumental or chemical analysis.

Shelf-life is controlled by three factors:

a.) Product characteristics (perishability, bulk density, concentration effects)

b.)Package properties (water vapour transfer, gas and odour transfer, light transmission,

package dimensions, package/product interactions)

c.)Distribution and storage environment (climatic and physical)

13. Aseptic packaging of foods

Aseptic packaging is the filling of sterile containers with a commercially sterile

product under aseptic conditions and then sealing the containers so that reinfection

is prevented.

The first aseptic packaging of food was carried out in Denmark by Nielsen.

Criteria for aseptic packaging system:-

1.) Able to be connected to the processing system

2.) Able to be effectively sterilized before use

3.) Able to carry out the filling, sealing and critical transfer operations in a sterile

environment.

4.) Able to be cleaned properly after use.

Sterilization processes used are- HTST and UHT.

Aseptic packaging systems may include carton systems, can systems, bottle systems,

cup systems, sachet and pouch systems.

14. Packaging of Microwavable Foods

Microwaves use electromagnetic waves at frequencies between 300MHz and 300

GHz.

Microwaves are generated by magnetron which consists of a vacuum tube with a

central electron-emitting electrode.

In microwave oven, foods are placed in an electromagnetic field at ambient

temperature and heat is generated by the food’s own ingredients.

Packaging materials can react in three ways to microwaves:-

a.) they can reflect the radiation

b.) absorb the radiation RAT characteristics

c.) transmit the radiation

Various packaging materials used to package microwaved foods:-

1.) Transparent materials

2.) Absorbent materials

3.)Shielding and field modification

15.Active and Intelligent Packaging

Smart packaging are defined as “doing more than just offer protection”.

Active packaging is defined as packaging in which subsidiary constituents have

been deliberately included in or on either the packaging material or the packaging

headspace to enhance the performance of the package system.

Intelligent packaging is defined as packaging that contains an external or internal

indicator to provide information about the history of the package and quality of the

food.

Smart Packaging Active Packaging Intelligent Packaging

Active packaging materials include: Intelligent packaging materials include:

A.)Oxygen absorbing materials a.)Quality/freshness indicators

B.) Ethylene adsorbers b.) Time-Temperature indicators

C.) Antioxidant Packaging c.) Gas concentration indicators

D.) Antimicrobial Packaging d.)Biosensors