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After the war, large quantities of aluminum foil became

available for commercial use. Its applications boomed with

the postwar economy. The ﬁrst formed or semirigid con-

tainers appeared on the market in 1948. Large-scale

promotion and distribution of food service foil in 1949

quickly expanded the market. Aluminum foil’s compat-

ibility with foods and health products contributes greatly

to its utility as a packaging material.

Standard aluminum foil alloying elements are silicon,

iron, copper, manganese, magnesium, chromium, nickel,

zinc, and titanium (see Table 2). These elements constitute

only a small percent (in most cases, no more than 4%) of

aluminum-foil alloy composition.

PROPERTIES

Chemical Resistance

Resistance of aluminum foil to chemical attack depends on

the speciﬁc compound or agent. However, with most

compounds, foil has excellent to good compatibility.

Aluminum has high resistance to most fats, petroleum

greases, and organic solvents. Intermittent contact with

water generally has no visible effect on aluminum other-

wise exposed to clean air. Standing water in the presence

of certain salts and caustics can be corrosive.

Aluminum resists mildly acidic products better than it

does mildly alkaline compounds, such as soaps and deter-

gents. Use with stronger concentrations of mineral acids is

not recommended without proper protection because of

possible severe corrosion. Weak organic acids, such as

those found in foods, generally have little or no effect on

aluminum. A clear vinyl coating, however, is recom-

mended for use with tomato sauce and other acetic foods.

Temperature Resistance

Since aluminum foil is unaffected by heat and moisture,

it is easily sterilizable and is actually sterile when

heat-treated in production. Unlike many packaging ma-

terials, aluminum foil increases in strength and ductility

at lower temperatures. Its opacity protects products that

would otherwise deteriorate from exposure to light (see

Table 3).

Mechanical Properties

The addition of certain alloying elements strengthens

aluminum. The alloys produced from these compositions

can be further strengthened by mechanical and thermal

treatments of varying degree and combinations. For this

reason, the mechanical properties of aluminum foil are

signiﬁcant to an understanding of its versatility.

The lowest, or basic, strength of aluminum and each of

its alloys is determined when the metal is in the annealed,

or soft, condition. Annealing consists of heating the metal

and slowly cooling it for a predetermined period of time.

Reroll-stock from which foil gauges are produced is an-

nealed (a process of heating and cooling) prior to the foil-

rolling operations to make it softer and less brittle.

All alloys are strain-hardened and strengthened when

cold-worked, as in foil rolling. When the product is wanted

in the soft condition, it is given a ﬁnal anneal (1).

CONVERTING

Aluminum foil is converted into a multitude of shapes and

products (see Table 4). Processes involved may include

converting mill rolls of plain foil by rewinding into short

rolls, cutting into sheets, forming, laminating, coloring,

printing, coating, and the like (4) (see Slitting and rewind-

ing; Laminating; Printing; Coating equipment).

Packaging products account for about 75% of the

market for aluminum foil (5). Aluminum foil is also used

in households and institutions as a protective wrap, as

well as for decorative and construction purposes.

Among packaging end uses, aluminum foil is formed

into semirigid containers produced from unlaminated

metal for frozen and nonfrozen foods, as well as caps,

cap liners, and closures for beverages, milk, and other

liquid foods (see Closure liners; Closures). It is also formed

into composite containers with ﬁlms and plastics to pack-

age powdered drinks, citrus and other juices, and motor oil

and other auto supplies (see Cans, composite).

Aluminum foil combined with other materials such as

paper or plastic ﬁlm can be used to package a host of basic

nonfood products, including tobacco, soaps and detergents,

photographic ﬁlms, drugs, and cosmetics (6).

When water-vapor or gas-barrier qualities are critical

to the success of a packaging material, aluminum foil is

usually considered. Aluminum-foil containers are odor-

less, moisture-proof, and stable in hot and cold tempera-

tures. They were originally developed to supply bakers

with cost-cutting disposable pie plates and bake pans.

A major reason for the wide use of aluminum foil in

packaging is its versatility. It is adaptable to practically all

converting processes and can be used plain or in combina-

tion with other materials. Aluminum foil can be laminated

to papers, paperboards, and plastic ﬁlms. It can be cut by

Table 2. Principal Aluminum-Foil Alloys

Alloy and Temper

(Aluminum

Association

Number) Aluminum, %

Principal Other

Elements,

Non-Heat-Treatable

1100–H19 99.00 0.12 Cu

1145–H19 99.45

1235–H19 99.35

1350–H19 99.50

3003–H19 97.00 0.12 Cu, 1.2 Mn

5052–H19 96.00 2.5 Mg, 0.25 CR

5056–H19 93.6 0.12 Mn, 5.0 Mg,

0.12 Cr

5056–H39

Heat-Treatable

2024–T4 91.8 4.4 Cu, 0.6 Mn,

1.5 Mg

Nominal compositions.

528 FOIL, ALUMINUM

any method and can be wrapped and die-formed into

virtually any shape. Foil can be printed, embossed, etched,

or anodized.

Foil Lamination

In many laminations, light-gauge foil is the primary

barrier against water-vapor transfer. While creasing can

create pinholes or breaks in this barrier, problems can be

minimized by proper lamination (see Laminating

machinery).

Laminations of foil and waxed paper have been popular

as overwraps and liners for cereal packages for more than

40 years. Snack foods that once presented a problem

because of their high oil content are now wrapped by

specially formulated foil-paper and foil-ﬁlm laminates.

Aluminum foil laminates have been designed to meet

exacting requirements of drugs used in transdermal med-

ication systems that deliver medication through the skin

at a constant rate over a speciﬁc period of time.

Peelable foil-laminated pouches protect transdermal

drugs. Space-shuttle astronauts wore a U.S.-quarter-sized

transdermal patch behind the ear to help prevent motion

sickness.

Printing

Either side of foil may be printed directly, or the foil may

be laminated to a reverse-printed clear ﬁlm to provide

attractive designs with accents. Use of transparent inks

through which the foil can be seen produces pleasing

metallic colors with no loss in brightness or sparkle.

The same presses and the same types of processes used

for printing paper and plastic ﬁlms are used for printing

on foil and foil-paper laminations. Processes include roto-

gravure, ﬂexography, letterpress, lithography, and silk

screen (1) (see Printing; Decorating). Inks for all of these

processes are readily available in formulations expressly

made for printing on aluminum (see Inks).

To provide anchorage for the inks, prime or wash

coatings are nearly always used on foil to be printed.

The coatings also provide a barrier that prevents offset-

ting of undesirable materials from the paper to the foil

surface.

Embossing

In-line or out-of-line printing and embossing units allow

designs of limitless combinations of color and form. Any

embossing pattern in foil produces two basic visual effects,

namely, three-dimensional patterns or illustrations and

continual reﬂective contrasts.

Foil embossing often is performed in continuous roll

form by passing the web or sheet through a roll stand

equipped with one engraved steel roll and a soft matrix

roll of paper. The pressure for embossing may be obtained

by maintaining the paper roll with the axis in a ﬁxed

position and using only the weight of the steel roll to

Table 3. Functional Properties of Aluminum Foil

Form Thickness Continuous rolls and sheets

0.00017–0.0059 in. (4.3–150 mm)

Hygienic Sterile when heat-treated in

production; smooth metallic surface

sheds most contaminants and

moisture of sterilization

Maximum width 68 in. (1.7 m) for pack-rolled lighter gauges;

72 in. (1.8 m) for gauges

Sterilizable Metal unaffected by heat and moisture

of sterilization (except for staining in

some cases)0.001 in. (25.4 mm) and heavier, single-web

rolled

Impermeability (WVTR)

0.001 in. (25.4 mm) and thicker is

impermeable; 0.00035 in. (8.9 mm) has a

WVTR of r0.02 g/100 in.

(0.065 m

);

24 h at 1001F (37.81C)/100th—WVTR

drops to practically zero when 0.00035-

in. (8.9-mm) foil is laminated to

appropriate ﬁlm

Nontoxic Inert to or forms no harmful compounds

with most food, drug, cosmetic,

chemical, or other industrial products

Tasteless, odorless Imparts no detectable taste or odor to

products

Corrosion resistance Aluminum’s natural oxide shielding, which

is maintained in the presence of air,

renders it substantially corrosion

resistant

Opacity permanence Solid metal, transmits no light; highly

corrosion-resistant in most

environments

Compatibility with

food, drugs, and

cosmetics

Nontoxic; corrosion-resistant to many

compounds in solution

Sealability Excellent dead fold and adhesion to a

wide variety of compounds

Formability Dead fold Insigniﬁcantly

magnetic

Provides excellent electrical,

nonmagnetic shielding

Nonabsorptivity Proof against water and wide variety of

liquids

Nonsparking The leading metallic material for

applications with volatile, ﬂammable

compounds

Greaseproof Nonabsorbent

WVTR = water-vapor transmission rate.

FOIL, ALUMINUM 529

depress the negative pattern into the paper roll (see

Figure 1).

FLEXIBLE FOIL PACKAGES

Flexible foil-containing packages are extremely popular

for food packaging because they provide superior ﬂavor

retention and longer shelf life than packages formed from

other ﬂexible materials. Flexible foil packaging is imper-

vious to light, air, water, and most other gases and liquids.

The packages protect contents from harmful oxygen, sun-

light, and bacteria (see Figure 2) (see Multilayer ﬂexible

packaging).

One of the most important ﬂexible-packaging applica-

tions of aluminum foil is the form/ﬁll/seal pouch (1).

Pouches are formed continously from roll-fed laminated

material and are ﬁlled and sealed immediately as formed

(see Form/ﬁll/seal, horizontal; Form/ﬁll/seal, vertical;

Pouches). The pouch is one of the oldest automated-

package forms. The retort pouch, developed in the early

1950s, represented a signiﬁcant advance in food packa-

ging. It is a ﬂexible package made from a laminate of three

materials: an outer layer of polyester for strength; a

middle layer of aluminum foil as a moisture, light, and

gas barrier; and an inner layer of polypropylene as the

heat seal and food-contact material (7) (see Retortable

ﬂexible and semirigid packages).

The Q-Pouch is a new foil-lined paperboard pouch that

can be turned into a drinking cup. A user of the package

simply rips the top edge along perforations and squeezes

the sides of the packet. Scored paperboard opens into a

hexagon-shaped cup.

Aluminum foil is also used to some extent for bag-in-

box liquid packaging (see Bag-in-box, liquid).

FOIL LIDDING

Another popular packaging application is the ﬂexible

closure or ﬂexible lid. The ﬂexible closure got its start

with single-service dairy creamers, yogurt, and cheese

dips. It is also widely used in the healthcare industry,

especially in hospitals, where the trend is toward dispo-

sable packaging (see Healthcare packaging). Liquid med-

ications are also packaged in single-dosage containers,

which are convenient and provide easy evidence of tam-

pering (8) (see Pharmaceutical packaging; Tamper-evi-

dent packaging).

Flexible lids were introduced in 1966 when a U.S.

Health Service regulation required that the pouring lip

of dairy containers be covered during shipment and

storage. Besides covering the pouring lip of the container,

Table 4. Classiﬁcations for Converted and Nonconverted

Aluminum-Foil End Uses

Packaging End Uses

Semirigid foil containers (including formed foil lids) produced

from unlaminated metal for

Bakery goods

Frozen

Nonfrozen

Frozen foods, other than bakery

Caps, cap-liners, and packaging closures for

Beverages and milk

Foods

Composite cans and canisters (including labels and liners for

composite cans) for powdered drinks; auto supplies; food

snacks; citrus and other juices; refrigerated dough; other

refrigerated and frozen products

Flexible-packaging end uses (including labels, cartons,

overwraps, wrappers, capsules, bags, pouches, seal hoods and

overlays for semirigid foil containers)

Food products

Dairy products—cheese, butter, milk, milk powder, ice cream,

dried and dehydrated food products—fruit, vegetables, potato

products, soup mixes, yeast

Baked goods—bread, cookies, crackers

Cereals and baking mixes—cereals, rice, cake mixes, frosting

mixes, macaroni products

Powdered goods—coffee, tea, gelatins, dessert mixes, drink

powders, cocoa, dry concentrates, sugar, salt

Meat, poultry, and seafoods (fresh, frozen, irradiated, dried,

retorted)

Frozen prepared foods

Confections—candy, mints, chewing gum, chocolate bars

(converted foil only)

Dry snack foods—potato chips, popcorn, including coated popcorn

Beverages—soft drinks, beer, distilled liquors, wines

Food products, NEC

(including pet foods)

Nonfood products

Tobacco—cigars, cigarettes

Soaps and detergents

Photographic ﬁlm and supplies

Drugs, pharmaceuticals, cosmetics, toiletries, kindred

products

Nonfood products, NEC

Military speciﬁcation packaging

Selected Nonconverted Foil Products

Packaging end uses (unmounted, unconverted foil stock sold to

end-users for candy and gum wraps)

U.S. Department of Commerce.

Not elsewhere classiﬁed.

On direct government orders only.

Reported by foil producers (rollers) only.

Figure 1. Foil embossing unit. An engraved steel roll, usually

the top roll, carries the design, and a matching paper roll becomes

the matrix. This matrix roll is constructed of layers of paper

(wool-rag) rings compressed solidly into one continuous mass and

mounted on an appropriate core.

530 FOIL, ALUMINUM

a heat-sealed foil lid offered a more reliable seal, longer

shelf life, and greater protection than other lidding

materials.

The use of inductive heat-sealing equipment instead of

conductive heat sealing is broadening the applications for

foil lidding. Inductive sealing does not heat the lid by

direct contact. Heat is brought into the lidding stock by a

magnetic ﬁeld through which the container and lid pass.

The magnetic ﬁeld heats the foil in the lid, and an effective

hermetic seal forms between the lid and the container.

Flexible foil lidding can be used on glass, plastic, or

composite cans. This key development enables the alumi-

num foil industry to provide tamper-evident packaging

(see Tamper-evident packages).

REGULATED PACKAGES

Aluminum foil is an integral part of many tamper-evident

packages. Although the term came into prominence only

in the 1980s, this kind of packaging has been on the

market before then. As now deﬁned by the Proprietary

Association, a tamper-evident package is ‘‘one which, if

breached or missing, can reasonably be expected to pro-

vide visible evidence to consumers that the package has

been tampered with or opened’’ (9).

Of 11 methods listed by the Proprietary Association

that conformed to the regulation when it was ﬁrst pro-

nounced, six featured aluminum foil as part of the tamper-

evident system.

For a system to be tamper-evident, its package cannot

be removed and replaced without leaving evidence. It is

extremely difﬁcult to mend or repair a foil-membrane seal

after it is broken or to return an aluminum rollon cap to its

original state once it has been removed.

One of the ﬁrst major laws that required protective

packaging was the Poison Prevention Packaging Act of

1970, which essentially said that drugs and dangerous

substances must be packed in child-resistant packages.

This type of package includes blister packs of plastic–foil–

paper combinations; tape seals of paper or foil which

adhere to the cap or shoulder of a bottle; and pouches

that can be tighly sealed.

ASEPTIC PACKAGING

Most aseptic packages are laminations of paperboard,

plastic, and aluminum foil. In aseptic packaging, the

product is sterilized with high heat and then cooled. The

package is sterilized separately, and then the sterile

product and packaging are combined in a sterile chamber

(see Aseptic packaging).

Foil provides superior adhesion for the containers that,

in the main, hold highly acidic products. In almost all

methods of aseptic container manufacturing, aluminum

foil is used as a barrier to light and oxygen.

ALUMINUM AND MICROWAVE OVENS

In 1984, Underwriters Laboratories undertook a study on

the use of aluminum foil trays to reheat food in microwave

ovens. Using various models of microwave ovens and

standard types of aluminum trays containing frozen foods,

the study concluded that (10):

The power density of microwave radiation emissions

did not exceed maximum allowable limits.

There was no signiﬁcant change in heat going into

various liquids and frozen foods in aluminum con-

tainers as compared to other containers.

The temperatures in the foods and liquids being tested

were generally comparable in the various

containers.

The foil trays containing different amounts of water

and empty trays produced no ﬁre emissions of ﬂam-

ing or molten metal.

The test trays used for heating frozen foods in accor-

dance with speciﬁc instructions did not increase the

risk of radiation, ﬁre, or shock hazard.

Susceptors are a unique and successful innovation in food

packaging for microwave heating of a variety of foods such

as pizza and popcorn (11). They are microwave-absorbent

materials used in the microwave oven to generate surface

heating on the food to induce browning and crispness. A

susceptor is typically constructed of a metallized PET ﬁlm

Figure 2. Features and constructions of pouches.

FOIL, ALUMINUM 531

(about 12 mm thick) laminated to a thin paperboard. The

paperboard provides dimensional stability, while the very

thin metal layer discontinuous layer of aluminum (usually

30–60 A

) is responsible for generating localized resistance

heating when exposed to microwaves.

SEMIRIGID PACKAGING

Other classiﬁcations of aluminum packaging include

semirigid and rigid containers. Semirigid containers in-

clude those that are die-formed, folding cartons, and

collapsible tubes. Die-formed containers are one-way dis-

posable devices such as pie plates, loaf pans, and dinner

trays. Folding cartons come in many sizes and shapes and

hold such products as dry cereals, eggs, and milk or other

liquids (see Cartons, folding; Cartons, gable top). Collap-

sible tubes were ﬁrst made of lead and used by artists

more than 100 years ago. In modern times, a proprietary

aluminum foil/ﬁlm version of the collapsible tube holds

toothpaste and products of similar consistency, including

hair coloring and depilatories (1) (see Tubes, collapsible).

Aluminum foil provides the barrier to permeation of the

oils used in most products and compounds that go into the

tubes.

Aluminum tubes have the advantage of providing light

weight, high strength, ﬂexibility, and good corrosion re-

sistance. Aluminum tubes also have low permeability and

offer quality appearance. Traditionally, aluminum collap-

sible tubes were impact-extruded, but a new process forms

the laminated rollstock into continuous tubing by use of

heat and pressure. The tubing is cut into individual

sleeves and is automatically headed by injection molding.

As opposed to ﬂexible containers that conform to the

shape of the product, semirigid containers have a shape of

their own. They can be deformed from their original shape

either while they are emptied (as in the collapsible tooth-

paste tube), or before they are ﬁlled (as with the folding

carton).

Die-formed aluminum containers are among the most

versatile of all packages. They easily withstand all normal

extremes of handling and temperature variation. A pro-

duct in an aluminum container can be frozen, distributed,

stocked, purchased, prepared, and served without soiling

a single dish.

Bare foil is used for most formed aluminum-foil pro-

ducts, but protective coatings are used on the containers

for some foods and other products. Although the frozen-

food tray is the most common, the aluminum-formed

container is available in scores of shapes and sizes from

the half-ounce portion cup to full-size steam-table contain-

ers for institutional feeding. Closures for these containers

vary from laminated hooding to the hermetically sealed

closure according to the amount of protection needed for

the product.

Folding cartons offer protective and display character-

istics unique in packaging and have some of the advan-

tages of both the ﬂexible and the rigid container. Before

use, when it is folded ﬂat, the folding carton offers the

storage economy of the ﬂexible bag. When it is ﬁlled, it

offers much of the protection of the setup box.

RIGID CONTAINERS

Composite cans and drums feature aluminum foil com-

bined with ﬁber. They are widely used for refrigerated

dough products, snack foods, pet foods, and powdered

drink mixes.

In some processes, a composite can is made up of

paper–polyethylene–aluminum foil–polyethylene lami-

nated stock with a foil-membrane closure. Cans are pro-

duced from preprinted gravure rolls of bottom aluminum

stock (see Cans, composite).

BIBLIOGRAPHY

Foil Division of the Aluminum Association, Inc., ‘‘Foil, Aluminum’’

in The Wiley Encyclopedia of Packaging Technology, 1st edi-

tion, John Wiley & Sons, New York, 1986, pp. 346–351; 2nd

edition, 1997, pp. 458-463.

Cited Publications

1. Aluminum Foil Manual, the Aluminum Association, Wa-

shington, DC, 2004.

2. The Story and Uses of Aluminum, the Aluminum Association,

Washington, DC, 1984.

3. G. Robertson, Food Packaging, Principles and Practise, 2nd

ed., Taylor and Francis, Boca Raton, FL, 2006.

4. Aluminum Foil Converted, U.S. Department of Commerce,

Washington, DC, 1981.

5. Aluminum Industry/Foil, the Aluminum Association, Wa-

shington, DC, www.aluminum.org., 2008.

6. M. J. Kirwan, Paper and Paperboard Packaging Technology,

Blackwell Publishers, London, 2005.

7. Food Technology, Institute of Food Technologists, June 1978.

8. Packaging Newsletter, the Aluminum Association, Fall 1983.

9. News release, the Proprietary Association, Washington, DC,

October 14, 1982.

10. Underwriters Laboratories, letter of July 23, 1984.

11. J. Osepchuk, ‘‘Microwave Technology’’ in Kirk–Othmer En-

cyclopedia of Chemical Technology, 5th edition, Vol. 16, John

Wiley & Sons, Hoboken, NJ, 2006.

FOOD PACKAGE DEVELOPMENT

KIT L. YAM

Department of Food Science,

Rutgers University,

New Brunswick, New Jersey

The food packaging development process requires many

considerations and activities. Below are some steps that

may be used as a reference to develop a food package.

Step 1: Determine Product/Package Requirements. The

ﬁrst step usually involves optimizing the product formula-

tion; determining the stability of the product particularly

to light, O

, and H

O; evaluating the processing methods,

existing equipment, plant capability; working with

532 FOOD PACKAGE DEVELOPMENT

marketing to determine the desired shelf life, distribution

chain, cost constraints, launch timing, product position-

ing, package size. During this step, the marketing group

typically leads the discussion based upon consumer data,

while the technical group provides input on feasibility.

Step 2: Select Package Materials and Equipment. This

step usually involves working with suppliers of packaging

materials and machinery to identify options; determining

cost and availability; comparing stock versus custom

package; working closely with product development to

better understand ingredients and possible issues relating

to packaging; complying with regulations. Since timing is

critical to package design, it is important to identify

potential issues that may delay the timeline.

Step 3: Evaluate Prototype Packages. This step usually

involves conducting shelf-life testing to determine quality

retention at ambient and elevated temperatures, conduct-

ing distribution testing to determine robustness and

integrity of package, conducting product/package interac-

tion testing; evaluating feasibility of scale-up at ﬁnal

production facility. Scale-up package at production facility

is important prior to initial run to identify potential

process issues.

Step 4: Test Packaging System in Market. This step

usually involves producing ﬁnal food packages; conﬁrming

that all major requirements are met; retrieving pack-

ages from market for evaluation and conﬁrmation,

monitoring consumer feedback during test market or

national rollout; reﬁning package/process design if neces-

sary. Final package is tested as part of a concept fulﬁll-

ment test to conﬁrm consumer acceptance of product and

package.

FOOD PACKAGING FOR SPACE MISSIONS

M. H. PERCHONOK

Department of Food Science,

Rutgers University,

New Brunswick, New Jersey

T. OZIOMEK

Department of Food Science,

Rutgers University,

New Brunswick, New Jersey

S. J . FRENCH

Department of Food Science,

Rutgers University,

New Brunswick, New Jersey

INTRODUCTION

The approach to National Aeronautics and Space Admin-

istration (NASA) food provisioning has changed over the

last 45 years and will continue to change to accommodate

the different mission proﬁles and vehicle designs. The goal

of NASA’s food scientists is to provide the crew with a safe,

nutritious, and acceptable food system while efﬁciently

balancing appropriate vehicle resources such as mass,

volume, and crewtime. Because future NASA exploration

missions will range in duration from 2 weeks to 6 months

to an eventual 2.5-year mission to Mars, certain require-

ments for food packaging have been established. Similar

to food industry needs, the packaging materials will need

to act as a barrier that can interface with the crew/

consumer, facilitate use of existing or new processing

methods, prevent light transmission, and meet puncture

requirements. However, unique to NASA is the require-

ment not to release toxins into the closed environment of

the vehicle (off-gassing) and to insure seal strength to

withstand changes in g-forces and atmospheric pressure.

In particular, oxygen and water vapor transmission will

need to be adequately prevented to maintain sensory and

nutritional quality for the duration of the missions. These

missions can be as long as 3 years. Mission speciﬁc

proposed oxygen transmission and water vapor transmis-

sion values have been calculated using maximum allow-

able ingress or egress values for current products, various

mission lengths, and the areas of two current pouch

conﬁgurations.

This article will provide a historical and current

perspective to NASA’s packaged food system. In addition,

as NASA returns to the moon and goes on to Mars, the

food packaging requirements will change, and potential

food packaging recommended attributes are provided.

HISTORY OF PACKAGING FOR NASA FOOD SYSTEMS

Mercury (1961–1963). Food packaging for space ﬂight

has been in use since Mercury 6 where John Glenn

consumed 119.5 g of pureed applesauce from an aluminum

tube. Mercury ﬂights used collapsible aluminum tubes

having Sunex 11-S lining that made use of a poly-

styrene extension tube called a ‘‘pontube’’ for consumption

(Figure 1). As ﬂights progressed, bite-size (ready-to-eat

single serving shelf stable items) and up to four rehydra-

table foods made their way into the available menu

Figure 1. Aluminum collapsible tube with ‘‘pontube’’ used for

project Mercury.

FOOD PACKAGING FOR SPACE MISSIONS 533

selection. Plexiglass dispensers were used for some bite-

size items, whereas a three-ply laminate of clear plastic

was used for other bite-size items and rehydratables (1).

However, the progression to include more types of food

items led to packaging related issues that resulted in

decreased caloric intake. During Mercury 9, astronaut

Cooper only consumed 696 kcal of the 2369 kcal available

to him at launch because of problems with the food

container and water dispenser during ﬂight (2).

Gemini (1965–1966). The Gemini food was packed in a

four-ply plastic laminate comprised of an inner and outer

layer of polyethylene and ﬂuorohalocarbon with polyester

layers between. Overwrap material for these ﬂights was a

polyoleﬁn-aluminum foil-polyester laminate (3).

For Apollo missions, the primary packaging material

used for the rehydratable and bite-size foods was a four-

ply laminate of polyethylene-Mylar (biaxially oriented

polyethylene terephthalate) -Aclar

(polychlorotriﬂuor-

oethylene)-polyethylene. Rehydratable food packages

used a one-way spring valve at one end for water insertion

and a folded polyethylene tube for zero-g consumption at

the other end. These rehydratable packages also con-

tained a separate compartment for a germicidal tablet

(1 gram of 8-hydroxyquinoline sulfate) for stabilization of

uneaten food residue. Figure 2 shows two examples of

rehydratable items used for Apollo missions.

Meal units, which were arranged by crewmember

nutrient requirements, mission timelines, and spacecraft

stowage-volume conﬁgurations, were overwrapped in a

four-ply aluminum foil/plastic laminate and evacuated to

a pressure of 29 inc. vacuum after a triple ﬂush with

nitrogen. Overwrapped meals were labeled by mission

day, meal, crewman (by color-coded Velcro

patch), and

serial number. Meals were attached to each other using a

nylon lanyard to ensure ease of sequential retrieval in

ﬂight (4).

Apollo (1968–1972). The Apollo missions increased in

duration resulting in a need to improve the food system.

During the Apollo missions, several improvements to the

food packaging were evaluated including an effort to use

nonﬂammable materials. Smith et al. (4) describe basic

design changes that were implemented, and results from

those changes are as follows:

. The meal overwrap material (four-ply aluminum

foil/plastic laminate) was replaced with polytriﬂuor-

ocloroethylene copolymer (Kel-F-82), which is a non-

ﬂammable material. This new material was the

primary cause for an increase in food system weight

of approximately 0.25 lb/person/day or 14% of the

baseline weight. Material thickness was found to

vary from 4 to 8 mils, with corresponding variation

in ﬂex strength. Relatively minor manipulations and

abrasion of the meal overwraps frequently resulted

in the formation of pinholes and loss of vacuum.

However, the Kel-F-82 manufacturer improved the

quality of the material through a process change

resulting in improved product strength and more

uniform thickness. The improved reliability of this

material resulted in a highly reliable food-package

material that was used with increasing frequency as

a primary food package for each succeeding Apollo

mission.

. The Bea-cloth lanyard used to attach sequential

meals was coated with Teﬂon

. Flaking of the

Teﬂon

coating presented a potential hazard of

inhalation of the resultant aerosol, even in one-g

conditions. As a result, Beta-cloth lanyards without

Teﬂon

coating were used.

During the second day of the Apollo 7 mission, the

crew reported a messy failure of a side seam of a

package of chocolate pudding (rehydratable). Ground

based operations were modiﬁed to ensure that heat

seals were at least 0.25 in. wide.

. Several water valves leaked food or water around the

outside the valve. A section of Teﬂon

shrink tubing

was used to form a leakproof friction ﬁt of the water

valve to the package.

. For rehydratable foods, a frequent point of package

failure was caused by the attachment of a germicidal-

tablet pouch to the outside of the ﬁnished package

by a heat-seal process. The germicidal tablet was

used to prevent microbial growth and subsequent

odor development. The germicidal pouch was relo-

cated as a portion of the basic-package blank cutout.

The time and effort required for fabrication were

reduced.

. Inefﬁciencies were present for packaging material

usage and processing. The length of the package for

semisolid foods was reduced resulting in a weight

reduction of 2 g for each package and of approxi-

mately 1 lb for a mission set of food. This also

resulted in a reduction of exposed combustible sur-

face area by 7 in

. for each package and 1470 in

. for a

mission set of food. The length of the rehydratable-

beverage package was increased. This change en-

abled provisioning of 8-oz servings instead of 6-oz

servings increasing the amount of beverage per unit

weight and volume of packaging material. Auto-

mated package fabrication was instituted resulting

in a package production increase from approximately

12 to 100 packages per hour.

. Pressure stresses at the package shoulder when food

was squeezed from the package were higher than

Figure 2. Rehydratable items packaged in four-ply laminate for

Apollo missions.

534 FOOD PACKAGING FOR SPACE MISSIONS

necessary. The angle of the package shoulder was

lowered from 45 1 to 301.

. The texture and ﬂavor quality of rehydratable foods

was lower as a result of the diameter of the mouth-

piece for rehydratable foods. The diameter for the

mouthpiece was increased form 0.75 in. to 1.25 in.

Skylab (1973–1974). The 1973 Skylab food system was

the most palatable and varied food system to be used in

space to date. All the planned food for the Skylab program

was launched with the ﬁrst mission, making it over

2 years old when the last crew consumed it. Therefore,

most of the food was packaged in aluminum cans to

maintain the 2-year shelf life. Frozen food, which required

heating, and some the thermostabilized items were pack-

aged in aluminum cans with a membrane under the lid to

prevent spilling while heating and to facilitate opening in

microgravity. All aluminum cans were sealed in canisters

designed to withstand the pressure changes from 14.7 to

5.0 psia between the ground and the spacecraft (Figure 3).

The primary package for beverages was a clear plastic

pouch with a reconstitution valve attached. Expandable

polymeric beverage containers were used (Figure 4).

CURRENT FOOD PACKAGING

The current state-of-the-art food packaging materials

employed for International Space Stations (ISS) (2000–

present) and Shuttle (1981–present) missions include

Smurﬁt Stone’s LCFLEX 70466 (LCF), Rollprint’s

RPP36-1080 (RPP), and Bayer’s Combitherm XX115

(COM115) and XX230 (COM230). Figure 5 illustrates

three of these materials.

LCF is a multilayer ﬁlm that is ideal for current

missions because it is lightweight, ﬂexible, and durable.

LCF includes an aluminum layer that allows the foods to

be processed after packaging without sacriﬁcing its high

moisture and oxygen barrier properties. It is currently

used for packaging of thermostabilized (retorted) and

irradiated items. However, LCF cannot be thermoformed,

is opaque, and the aluminum layer presents a solid waste

issue for long duration missions.

COM115 and COM230 are clear polymers currently

used for packaging bitesize (COM115 only) and freeze-

dried items. COM230 is currently thermoformed into a

tray to hold freeze dried items, and COM115 is used as a

lid. Thermoforming COM230 results in areas with de-

creased thickness and thus reduced barrier capability.

Freeze-dried and bite-size items packaged with COM

materials are vacuum packed to 29 or 21 in. vacuum.

The COM only provides a 1-year shelf life, which is only

adequate for shuttle missions. Therefore, for ISS, menu

items packaged using COM materials are overwrapped

using RPP to provide additional barrier capability (Figure

6). Use of this additional packaging layer creates addi-

tional upmass and trash aboard the ISS, and crewmem-

bers have commented on the inconvenience of having to

open two separate packages for each food item.

NASA DESIGN REFERENCE MISSIONS (DRM)

NASA’s Exploration Systems Architecture Study (ESAS)

identiﬁed seven design reference missions (5). They in-

clude three DRMs for ISS-related missions, three for lunar

missions, and one for an 18-month surface mission to

Mars. The timelines relative to food packaging require-

ments associated with these DRMs vary from

7 days plus travel for Lunar Sortie missions, to 6 months

plus travel for ISS and Lunar Outpost missions, to

18 months plus travel for Mars Exploration missions.

These mission timelines can affect provisioning ap-

proach and inﬂuence the packaging material’s primary

requirement driver. For Mars Exploration missions, the

primary driver is shelf life longevity. For Lunar Sortie

missions, the primary driver may shift from shelf life

longevity to an ability to safely handle cabin depressur-

ization. However, for any mission, efﬁciency will always

play a role in material selection.

VEHICLE DESIGNS

Temperature, relative humidity, and pressure ﬂuctuations

in the vehicle as well as exposure to radiation will

Figure 4. Expandable beverage container used for Skylab

missions.

Figure 3. Easy open can used for Skylab missions.

FOOD PACKAGING FOR SPACE MISSIONS 535

inﬂuence the effectiveness of any packaging material in

preserving food quality. A vehicle’s design can mitigate or

increase the affect of these conditions. A vehicle design can

also affect the required interface characteristics of the

package. For example, a vehicle may possess a hydration

interface, which will affect the design of packaging inter-

face (currently a septum for freeze-dried and beverage

items).

SHELF LIFE

Packaging materials are currently used to prevent ingress

and egress of mass. Of primary concern to NASA is the

ingress of oxygen and water vapor. Packaging materials

can decrease the oxygen available for chemical reactions

by slowing the transmission of oxygen to the food product.

If oxygen is not minimized, the resulting compounds from

Figure 5. Composition, order and thickness of layers within LCF (top), COM115 (Layer thicknesses are proprietary, therefore are not

provided), and RPP (bottom) packaging materials. COM230 is composed of the same materials as COM115, but the thickness of individual

layers is not relative to overall thickness.

Figure 6. Freeze-dried item in primary COM packaging (left) and with RPP overwrap (right).

536 FOOD PACKAGING FOR SPACE MISSIONS

autoxidation and lipid oxidation will impart a variety of

sensory notes that will likely be objectionable to the

consumer. This will generally result in lower acceptance

of the food product and hence inﬂuence shelf life.

To prevent unacceptable oxygen quality degradation

effects over a speciﬁed mission timeline, the required

oxygen transmission rate of a particular packaging mate-

rial must be deﬁned. In some instances, certain assump-

tions must be made or at minimum, a range of values

should be provided. For example, the assumptions for

mission timelines may add 180 days for prepositioning of

food provisions. Or, the area of the packaging material

may change as packaging conformation changes.

Water vapor transmission through the packaging ma-

terial is also of concern to NASA as it affects the hydration

characteristics of dried food items, which can lead to

unacceptable texture characteristics. Packaging materials

can pose a safety concern if transmission rates are sufﬁ-

ciently high enough to raise water activity (A

) above 0.65

(mold growth) or 0.86 (Staphylococcus aureus) (6) within

food items not undergoing a sterilization process.

NASA PACKAGING RECOMMENDED ATTRIBUTES

Several common attributes for food packaging materials

cross over between missions as well as ground-based

operations. Because water and oxygen transmission re-

commended rates are related to required shelf life of the

food, these attributes are listed under the speciﬁc missions.

Light Transmission. In many cases, the food packages

are stowed in an opaque container. Hence, light induced

reactions are minimized within the food product.

Offgas Properties. Because the vehicle is a closed en-

vironment, NASA has a unique off-gassing requirement

for all materials ﬂown. The packaging material should not

produce volatiles that would prove harmful to crewmem-

bers. Off-gas levels for compounds will not exceed levels

set forth by the Toxicology Laboratory at NASA’s Johnson

Space Center.

Processing. No refrigerators or freezers for the food are

available onboard the NASA vehicles. Hence, the food

must be shelf stable. Packaging materials should accom-

modate the processing method used for microbial and

enzymatic stabilization. For example, a material may

need to be able to withstand the heat extremes present

in retort/thermostabilized processing without loss of in-

tegrity. Or, a material may need to allow microwaves to

pass.

Puncture Strength. Puncture strength is important for

the NASA food packaging materials. Damage to many food

packages on board the vehicle can result in a compromised

food system, which can compromise the crew health. To

measure the puncture strength of each material, a TA-

XTPlus (Texture Technologies, Scarsdale, NY) texture

analyzer is used. A TA-108 tortilla test rig is used to ﬁx

the samples for testing. TA-52 (2-mm cylinder) and TA-55

(5-mm cylinder) probes are used to penetrate the samples.

A test speed of 2.0 mm/s is used to a distance of 25 mm.

In general, punctures from food contents can be identi-

ﬁed during ground-based operations by loss of packaging

integrity. An in-to-out puncture strength of 2.5 kg is

required. An out-to-in puncture strength of 1.5 kg is

required.

Radiation. Packaging materials can potentially reduce

or mitigate the effects of radiation on food items. As

radiation effects on food require additional research and

the amounts and types of radiation will be mission speciﬁc

these requirements are still to be determined.

Seal Strength. Packaging materials should withstand

speciﬁed environmental and stowage conditions without

degrading or losing barrier integrity. Periods of reduced

or zero pressure will place additional strain on package

seals. Periods of increased pressure can also occur. To

withstand these conditions, a seal strength of 3 kgf/in. is

required.

To measure the tensile strength of seals a TA-XTPlus

(Texture Technologies, Scarsdale, NY) texture analyzer is

used. A TA-96 tensile test ﬁxture is used to ﬁx the samples

for testing. A test speed of 1.5 mm/s is used to a distance of

75 mm. Seal tensile strength is measured using a 1.25 in.

length by 1 in width attached on each side of the seal to the

clamp.

Material Transmission Rate Calculations. Current space

food products were grouped into two main categories:

freeze dried/natural form food items and thermostabilized

food items. The average mass was determined for each

category, and the worst case scenario for O

ingress and

O ingress/egress was used for calculating the required

material transmission rates. The transmission rates re-

quired to maintain the proper shelf life were determined

for various mission lengths.

The following formula was used to determine the

maximum allowable oxygen ingress for a speciﬁc product

using information obtained from Table 1 below.

ProductmassðgÞMaxO

ðppmÞK

ð1Þ

K = 22 400 cc = 1 mole ideal gas at 1 atm and 201C

C = 32 g = Molar mass of O

Oxygen transmission rates (OTR) were calculated

using information from Table 1 and equations (1) and

(2). For example, the required oxygen transmission rate

for freeze-dried and natural form food items on lunar

sortie missions was calculated using the following infor-

mation: a VO

value of 0.0875 cc determined using a

maximum O

ingress value of 5 ppm (Table 1), a food

mass value of 25 g, which is the average mass of our

current products, a T value of 195 days, and an A of

0.0232 m

, which is the area of the current bite size pouch.

Values for determining rates on thermostabilized items

were modiﬁed to use a VO

value of 0.112 cc determined

using a maximum O

ingress value of 1 ppm (Table 1), a

food mass value of 160 g, which is the average mass of our

FOOD PACKAGING FOR SPACE MISSIONS 537