CHAPTER 21

PRINCIPLES of FOOD PACKAGING

FUNCTIONS of FOOD PACKAGING

Preservation

Protection from physical damage, chemical attacks, and contamination from biological

vectors including microorganisms, insects, and rodents

Must aid consumers in using products

Serves to unitize or group product together in useful numbers or amounts

Must be able to communicate and educate

Must be efficiently filled, closed, and processed at high speeds in order to reduce costs

REQUIREMENTS for EFFECTIVE FOOD PACKAGING

1. Nontoxic

2. Protect against contamination from microorganisms

3. Act as a barrier to moisture loss or gain and oxygen ingress

4. Protect against ingress of odors or environmental toxicants

5. Filter out harmful UV light

6. Provide resistance to physical damage

7. Transparent

8. Tamper-resistant or tamper-evident

9. Easy to open

10. Have dispensing and resealing features

11. Easy to dispose

12. Meet size, shape, and weight requirements

13. Have appearance, printability features

14. Low cost

15. Compatible with the food

16. Have special features such as unitizing groups of product together

TYPES of CONTAINERS

1. Primary Container

Comes in direct contact with the food

Nontoxic and compatible with the food and cause no color, flavor, or other

foreign chemical reactions

2. Secondary Container

An outer box, case, or wrapper that holds or unitizes several cans, jars, or pouches

together but does not contact the food directly

Make possible to distribute in glass jars without the corrugated secondary carton

to protect against breakage

Must protect the primary containers from damage during shipment and storage

Must prevent dirt and contaminants from soiling the primary containers

Must unitize groups of primary containers

3. Tertiary Containers

Group several secondary cartons together into pallet loads or shipping units

Aid in the automated handling of larger amounts of products

FORM-FILL-SEAL PACKAGING

Containers may be formed in-line by assembly from roll stock or flat blanks just ahead of

the filling operation in the food-handling line.

Today most flexible containers, whether made from paper, foil, or plastic resulting in

great savings in handling labor, container transportation costs, and warehouse storage

space

Milk Carton System – cartons were assembled from coated fiber flats, filled, and sealed

HERMETIC CLOSURE

Hermetic – a container that is sealed completely against the ingress of gases and vapors;

impervious to bacteria, yeasts, molds, and dirt from dust and other sources

Non-hermetic – prevents entry of microorganisms; allow some gases or vapors to enters

Hermitically sealed containers not only protect the product from moisture gain or loss

and oxygen pickup from the atmosphere but are essential for vacuum and pressure

packaging

Most common are rigid metal cans and glass bottles

FOOD-PACKAGING MATERIALS and FORMS

Metal, glass, paper and paperboard, plastics, and mirror amounts of wood and cotton

fiber

Variety of Forms: rigid metal cans, flexible aluminum foils, glass jars and bottles, rigid

and semi-rigid plastic cans and bottles, flexible plastics made from many different films

used for bags, pouches, and wraps, paper, paperboard, and wood products in boxes,

pouches, and bags, and laminates or multilayers in which paper, plastic and foil are

combined to achieve properties unattainable with any single component

Encompasses the equipment and machinery for producing or modifying certain

packaging materials, for forming them into final containers, for weighing and dispensing

of food materials, for vacuumizing or gas flushing the containers, and for sealing the final

packages

METAL

Two basic alloyed metals used: steel and aluminum

Steel – used primarily to make rigid cans; can withstand the pressure stresses of retorting,

vacuum canning

Beading – horizontal ribbing to increase rigidity

Aluminum – used to make cans as well as thin aluminum foils and coatings; resistant to

atmospheric corrosion, and can be shaped or formed easily; works well in very thin

beverage cans that contain internal pressure

Tin Can – steel used for cans are coated with a thin layer of thin to inhibit corrosion

METAL CANS

Its hermetic property is a remarkable engineering achievement when one considers that

cans are manufactured and later sealed at speeds exceeding 1000 units per minute and

defective cans are fewer than one in many tens of thousands.

CAN CONSTRUCTION

Two basic types of metal cans based on method of construction; Three-piece and Two-

piece

Three-Piece Cans – comprised of a cylindrical body and two end pieces

Two-Piece Cans – made from one single body and end unit and one can end piece which

is applied after the can is filled with product; do not have side seams

CAN CORROSION

Steel cans are protected from corrosion by rust pitting by a thin electronically deposited

coating of thin

Tin has been replaced by chromium or base steel by giving special rust-inhibiting

treatment called “passivation” – tin-free – lower cost

CAN SIZING

Cans are given standard size designations based on their diameter and height in whole

inches plus sixteenths of an inch.

Example: A 303 by 404 can has a diameter of 3 3/16 in. and a height of 4 4/16 in.

GLASS

A chemically inert and an absolute barrier to permeation of O2 or water vapor

Limitations: susceptibility to breakage, which may be from internal pressure, impact, or

thermal shock, its weight which increases shipping costs, and the large amounts of energy

required for forming into containers

Primarily formed from oxides of metals, with the most common being silicon dioxide

which is common sand

Controlled mixture of sand, soda ash, limestone, and other materials made molten by

heating to about 1500 degC

GLASS CONTAINERS

Hermetic, provided the lids are tight; lids have inside layers of a soft plastic material

which form a tight seal against the glass rim.

Vacuum packed, and the tightness of the cover is augmented by the differential of

atmospheric pressure pushing down on the cover

PAPER, PAPERBOARD, and FIBERBOARD

Paper – thin, flexible, and used for bags and wraps

Paperboard – thicker, more rigid, and used to construct single-layer cartons

Fiberboard – made by combining layers of strong papers and is used to construct

secondary shipping cartons

Corrugated Paperboard – used to construct shipping cartons because of the wavy inner

layer of paperboard used in its construction

Kraft Paper – the strongest of papers and in its unbleached form is commonly used for

grocery bags; commonly used as butcher wrap; Kraft – German word for strong

Greaseproof or Glassine Papers – paper pulp that undergo acid treatment to modify the

cellulose and give rise to water- and oil- resistant parchments of considerable wet

strength

PLASTICS

Plastics – a broad group of materials that have common property of being composed of

very large long-chain molecules

Can be formed in an almost infinite number of shapes

Copolymers – plastics that combine different monomers into the same polymer molecules

to form materials with combined properties

Homopolymer – if the plastic resin is made of just one type of monomer

LAMINATES

Commercial laminates containing up to as many as eight different layers are commonly

custom-designed for a particular product.

May be formed by bonding with a wet adhesive, dry bonding of layers with a

thermoplastic properties, and special extrusion techniques

Coextrusion – simultaneously forces two or more molten plastics through adjacent flat

dies in a manner that ensures laminar flow and produces a multiplayer film on cooling

RETORTABLE POUCHES and TRAYS

Flexible materials combined to withstand even the adverse conditions of retorting

encountered with low-acid foods

Advantages: shorter retort times, which can produce high quality products and save

energy, lighter weight, increased compactness, easier opening, and easier disposability

Retortable Pouches – constructed of a three-ply laminate consisting of (1) on an outer

layer of polyester film for high-temperature resistance, strength, and printability, (2) a

middle layer of aluminum foil for barrier properties, and (3) an inner layer of

polypropylene film that provides heat-seal integrity

Retortable Trays – constructed from multilayers of polymers, one of which is ethylene-

vinyl alcohol to provide an oxygen barrier; often sealed with a polymer-foil laminated

film

EDIBLE FILMS

Spray drying various flavoring materials emulsified with gelatin, gum Arabic, or other

edible materials to form a thin protective coating – microencapsulation

Used to coat fresh fruits and vegetables to reduce moisture loss and to provide increased

resistance to growth of surface molds

WOOD and CLOTH MATERIALS

Woven cloth and cotton bags are used to a limited extent, mostly for bulk shipment of

grains and flours.

Wire-wound wood strips have been used to make crates for fresh fruits and vegetables.

Solid wooden crates are used for transporting iced fish.

PACKAGE TESTING

Measure quantitatively the protective properties of packaging materials and entire

containers; divided into chemical and mechanical parameters

Chemical Tests – used to identify plastics, determine if portions migrate to foods, and

measure resistance to greases

Mechanical Tests – barrier properties, strength, heat-seal ability, and clarity

Water vapor transmission rates (WVTR) can be measured by sealing sheets and films

across the opening of a vessel that contains a weighed quantity of a desiccant material.

Gas transmission rates can be measured by an instrument which uses the test film to

separate an inert gas from the test gas.

Resistance of packaging films to acids, alkalies, and other solvents can be measured

quantitatively by incubating the films in the solvent under controlled conditions and then

determining either the degree of leaching of the film into the solvent or changes in the

physical properties of the recovered films.

PACKAGES with SPECIAL FEATURES

Package that have some type of added convenience feature. Ex. “boil-in-bag” package

Permeable to grease, nontoxic, compatible with the food, transparent, capable of being

evacuated and heat-sealed under vacuum, attractive, tamper-evident, easy to open and

dispose of, light in weight, requires little storage space, and is low in cost

Its materials and seals withstand freezing temperatures and the expansion of foods frozen

within it.

The plastic shrink package protects food against contamination and yet lets the costumer

see the meat.

MICROWAVE OVEN PACKAGING

Must be transparent to microwaves and able to withstand the temperatures encountered in

heating foods in the microwave oven

Most common used materials are made of plastics.

Disadvantage: heating surface does not get hot itself

Susceptors – cause foods to brown in a microwave oven; improves the quality of popcorn

popped in a microwave oven

HIGH BARRIER PLASTIC BOTTLES

Do not break when dropped, and can be incinerated without the production of toxic,

corrosive, or noxious compounds beyond those found in burning household or municipal

trash

Reduces cost throughout the production and shipping channels

Allow for easier dispensing of viscous products such as ketchup

ASEPTIC PACKAGING in COMPOSITE CARTONS

Aseptic Packaging – aseptically filling the sterilized composite paper cartons with sterile

liquid products

Allows food to be packaged in relatively inexpensive flexible containers which do not

require refrigeration

The packaging material is made from laminated roll stock consisting of polyethylene,

paper, aluminum foil, and a coating of ionomer resin.

MILITARY FOOD PACKAGING

Packages that simplify preparation and consumption of the food

Can undergo a rapid exothermic reaction

Too expensive

PACKAGING and COMMUNICATION

Determines a product’s sale or rejection

Package’s color and symbolism must be considered

FOOD LABELLING

It is important to ensure that the consumers are given complete and useful information of

the products they purchased.

3 types of Information n the food package:

1. Mandatory information required by the different laws governing food packaging and

labeling

2. Optional or voluntary information

3. Information by the manufacturer that helps the consumer understand the use of products

such as instructions for preparation and recipes

Information that must appear on the labels:

1. Food name

2. Net quality of contents

3. Ingredients – list of ingredients in descending order by weight

4. Company Name

5. Product dates

Pull dates – last date the product should be on sale

Best if used by – shelf life for the optimal quality

Pack date – date food was packaged

Expiration Date – last date on which the product should be eaten

6. Nutrition Information – nutrition facts, nutrient content claims and health facts

7. Other information such as grades of food products, bar code or product code, religious

symbols which indicates the product meets certain religious qualifications, warning

labels specifically such as ingredient labeling which can be allergic to some consumers

SAFETY of FOOD PACKAGING

MIGRATION from PLASTICS

Plastics are not completely inert to foods.

Plastics must have approval from regulatory agencies for the intended use.

CONTAMINATION

Preventing contamination of food and its recontamination depends primarily on

packaging.

ENVIRONMENTAL CONSIDERATIONS

Landfilling – the most common way of disposing of solid waste

Source Reduction – the use of less material when packaging foods

Metal and glass containers are heavy and require considerable energy to transport and

melt.

Recycling of glass is not always feasible because of its lower economic value.