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AGRICULTURE
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UNIVERSITY OF ILLINOIS
LIBRARY AT URBANA-CHAMPAIGN
L161— O-I096
JUN
t
1
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AGRICULTURE LIBR
Digitized by the Internet Archive
in
2011 with funding from
University of
Illinois
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http://www.archive.org/details/reusingfoodpacka1320brew
Reusing
Food Packaging
Is It
.
.
.
Safe?
DHT 2
AG
8
Library
M. Susan Brewer
University of Illinois at Urbana-Champaign
College of Agriculture
Cooperative Extension Service
Circular
1320A
Helping You
Put Knowledge to
Cooperative
Extension
Service
University of
at
Work
Illinois
Urbana-Champaign
College of Agriculture
This publication was prepared by M. Susan Brewer, Extension Specialist, Foods and Nutrition, Division of
Foods and Nutrition, University of Illinois at Urbana-Champaign.
Edited by Francine
Weinbaum
Designed by Joan R. Zagorski
Urbana,
July 1992
Illinois
Issued in futherance of Cooperative Extension Work, Acts of May 6 and June 30, 1914, in cooperation with
the U.S. Department of Agriculture. DONALD L. UCHTMANN, Director, Cooperative Extension Service,
University of Illinois at Urbana-Champaign.
opportunities in programs and employment.
.5M— 7-92— 1320A— fw
The
Illinois
Cooperative Extension Service provides equal
Introduction
How does our food get on the
Many consumers
an essential
component in the complex distri-
aging because they are concerned
with protecting the environment.
bution system which moves agri-
Recent years have brought
table? Packaging
cultural products
is
from their point
of origin to their point of con-
sumption. Along with our culture,
our packaging of food has
become increasingly specialized
and complex. Sterile boxes of
fruit juice, plastic
that
food pouches
can tolerate pressure canning,
reuse food pack-
in-
creased environmental pollution
and decreasing natural resources
and landfill space. But improper
reuse of food packaging can threat-
en health. So
it
is
important to
follow certain guidelines (see
page
four).
For example
it
is
gen-
erally safe to reuse glass that has
and microwave-safe containers
are but a few examples of specialized food packaging which did
not exist twenty years ago. Food
been used
packaging has several functions
ing materials used for protecting
other than
tection.
its
primary one of pro-
Packaging protects food
from microbial and other environ-
for food,
but not to
re-
use plastic or paper. Understanding the uses, specialized functions,
and
limitations of packag-
consumer foods can help consumers
make
safe decisions regarding
the reuse of packaging materials.
mental contaminants, and from
damage during distribution. It
also offers the consumer nutrition and ingredient information,
cooking instructions, product
This circular discusses the following topics:
1.
commercial
sterilization tech-
niques that keep microbes out;
weight, brand identification, and
pricing.
2. glass, plastic,
and paperboard
packaging of food;
and includes
3. easy-to-follow guidelines for
reusing food-packaging materials;
4. a glossary of food-packaging
terms for the consumer
to take the
edgeable.
who wants
time to become knowl-
Keeping
Microbes Out
Establishing microbiological stability is of
primary importance
for
most food products. Early food
packaging had to be able to tolerate heat so that the
product could
be canned (terminally sterilized
in the container). Glass
and
tin
(which uses high temperatures
very short times), and
irradiation.
rials
used
for
gamma ray
The packaging mate-
for these
new
processes
must be sterilized before they are
used; methods used to sterilize
packaging include hydrogen per-
cans were the original processed-
oxide or steam treatments, expo-
food packages because they could
sure to ultraviolet light, or
tolerate sterilization temperatures.
ray irradiation.
Because food flavors are apt
are "hot-filled" at 170°F, so the
to
gamma
A variety of foods
change during heating, a variety
chemically sterilized packaging
of sterilization techniques have
been designed to kill or remove
microbes from food products us-
must be able
ing
little
no heat processing.
or
These techniques include the use
of hydrogen peroxide treatments,
to tolerate
tempera-
tures slightly above 170°F. Pack-
aging materials that tolerate these
processes will not always tolerate
temperatures over 180°F without
substantial breakdown.
aseptic packaging (packaging in a
sterile
environment), ultra-high
temperature (UHT) sterilization
Glass
Versus
Plastic
and
Paperboard
Most packaging materials are designed for one use. With the ex-
board are designed to be recycled
ceptions of glass containers re-
not
quiring user deposit and limited-
into
new packaging forms that do
come into contact with food.
that
consumers
These recycled forms can be used
in outer layers of a food package
or as containers for foods encased
will take the product
home, then
in other materials.
use polycarbonate
facturers
assume
bottles,
manu-
discard or recycle the packaging.
Packaging
ingly.
When manufacturers
designed accord-
is
Packages are designed to
tolerate the type of food
system
design a
packaging system, they consider
the type of food (high-acid versus
(acid, base, alcohol, or fat) that
low-acid), the susceptibility of the
will be contained within them.
food to light and oxygen (milk,
No
fruit juice),
safety
is
systems or
implied
for
for other
food
reuse of that pack-
age in ways not suggested for the
the
cal protection
the
amount
amount
needed
of physi-
(eggs),
and
of product visibility
They
original food product. In general,
desired (fresh meats).
glass is the only packaging mate-
consider the amount of heat to be
rial
designed
for
reuse that uses
the packaging over again in
original form. Plastic
its
and paper-
also
sterilization, the con-
ally layers of different polymers.
and the type of "home
Each layer makes a contribution
used during
tainer size,
processing" to which the product
to total
package performance.
will be subjected (for example,
microwaveable
pizza).
Other con-
siderations include the cost
availability of the
and
packaging mate-
the food product, a problem that
can be aggravated by heat and by
the presence of a food into which
the plasticizing chemical will dis-
Flexible plastics
small amounts
may contain
(1 to 2
percent) of
solve (for example,
oil,
acid, or
alcohol). Migration of the
other substances that perform
pound
com-
increases with length of
and temperature,
specialized functions. These "ad-
contact time
finished product (plastic versus
ditives" include catalysts to aid in
and
glass soda bottles), recyclability
the polymer formation reaction,
est
antioxidants to prevent oxidation
between film and foods with high
of the packaging material, stabiliz-
fat
rial,
the cost of transporting the
(plastic versus paper),
sumer
and con-
attitudes about packaging.
levels of migration are high-
when there
content
at
is
direct contact
the surface.
ers to prevent degradation of the
Most
packaging material
plastics are considered
"high-barrier" packaging materials.
They exclude moisture and
when
it is
heated or exposed to ultraviolet
radiation,
and
plasticizers. Plasti-
most gases (including oxygen),
and they can be either optically
clear or opaque. Because of their
unique characteristics, plastics
are becoming the most important
cizers increase the flexibility of
packaging material for food prod-
rigid substance. Plasticizers
plastics.
They
intersperse around
the polymer molecules and pre-
made
of plastics.
may
and many have
relatively
low melting points themselves.
There has been some concern
about the migration of plasticizers
produced from base
polymers called "resins." Most
Plastics are
actual packaging applications in-
volve several types of resins.
Structural polymers such as poly-
ethylene (PE) and polypropylene
(PP) provide mechanical properties (strength, rigidity,
resistance) at
low
abrasion
cost. Barrier
polymers such as polyvinylidene
chloride (PVDC) and ethylene vi-
nyl alcohol
(EVOH) provide
pro-
tection against transfer of gases,
and odors. Tie resins (adhesive resins) bond the structural
and barrier resins together. Heatflavors,
seal resins provide
package
clo-
sures in flexible packages. In fact,
many
"plastic" packages are actu-
If
substances are
shown
to
migrate from the packaging into
the food, they are treated as "incidental food additives" and toxico-
plastic,
is
tact.
logical studies are
the
aging
packaging materials for food con-
other so tightly that they form a
ucts.
than 90 percent of flexible pack-
tion assesses the initial safety of
vent them from bonding to each
lower the melting point of the
The packaging industry is
largest user of plastics; more
The Food and Drug Administra-
out of the packaging material into
conducted in
order to establish safety standards.
The
safe reuse of packag-
ing materials has been studied
much
less,
but some generaliza-
tions can be
made.
Guidelines
for
Reusing
Food-Packaging
Materials
1.
Packages from products other
4.
Do
not reuse porous packag-
than food should never be used
ing materials such as paper,
as food containers. They have
paperboard, and expanded foams
not been tested for safety with
(for
may
food systems, and they
con-
amounts of nonfood
residues. (For example, do not
example, styrofoam cups and
foam meat
trays).
They have
air
spaces that will harbor food par-
tain small
ticles
and microorganisms.
use plastic laundry detergent
buckets for storing dry cereal.)
5.
Do
not reuse microwave pack-
ages that contain "heat suscep2. Glass
can be reused
foods and for
is
all
originally
what food
There
is
should not be used
The
material
is
more
grate into the food
likely to mi-
if it is
used
again.
for
howrecommendadiscussed below (number 3).
The
may
home
pressure processing in the
canner.
hold the
be damaged by the original use.
an ex-
ception to this rule: single-use
glass jars
that
crisping.
susceptor to the package
packaged in the
glass container.
browning or
The adhesives
processes. This
true regardless of
was
tors" for
for all
lid or cover,
6.
It is
better not to store foods
ever, is subject to
with strong odors or flavors in
tions
used food packages; the packag-
re-
ing material might absorb the
Reuse packaging materials
only with the following:
chemicals that produce the odor
3.
• foods similar in
in sugar,
fat,
acidity
or flavor
and
or alcohol content
to the food originally
in the material.
Do
packaged
not use a
salad dressing containing
a substantial
amount
of vinegar.
• foods that will be exposed
same types of processes.
to
the
Do not melt butter in the microwave oven using a plastic margarine container. In general, do
not subject food packages to
heat unless the instructions on
the original package give heat
ing information.
Many
food
products are "hot-filled" into
containers at low temperatures.
These packages will not
ate heating.
release
them
into a
ditionally,
rials
some packaging mate-
allow certain chemicals to
pass through them, transferring
plastic shortening container to
make
and
subsequently stored product. Ad-
toler-
odors or flavors to other foods
stored in the
same
area.
7.
When materials
are safe for use
microwave oven, they are
usually labeled for such use.
If you do not know whether the
in the
material
is
safe for use in the
microwave, don't use
it.
Soft
plastics are especially likely to
flake, blister,
deform, and melt.
This allows plastic polymer or
you
9. If
bag
are using a flexible film
11. Use only "food-grade paper"
bread wrapper for food
in direct contact with food prod-
like a
storage,
always use
it
with the
materials can contain residues
if
they
with
come
into direct contact
the film over the food with toothpicks.
There should be no direct
contact between the film and the
food.
Do
not seal the contact edge
between the film and the container. If you do, you may be
burned by the steam that builds
up during heating. This steam
can escape rapidly
move
the film.
when you re-
which would be unacceptable
for contact
with food are manu-
minimize residues,
If
you
store a
container for food storage.
Many
up small amounts of
the substances stored in them and
release them later. Motor oil
plastics pick
stored in plastic milk jugs will
later
you
be present in lemonade
store
in
foods. Paper products destined
which
and the fin-
factured by processes
it.
nonfood item in
a food container, do not reuse the
Suppose you are using a flexible plastic wrap to cover a container of food you are heating in
the microwave. Be sure to "tent"
and the raw
may contain materials that are not
meant for human consumption.
These inks may migrate into food
10.
8.
Paper processing uses a va-
riety of chemicals,
additives to penetrate into the
food.
ucts.
printed side out. Printing inks
lemonade
container.
in the
if
same
ished product
is
routinely tested.
6
A Glossary
of
Food-Packaging
Terms
Food-grade plastics often have
AN
information embossed into the
Acrylonitrile
bottom of the container. The type
of plastic material
may be
to
by an acronym such
or
EVOH.
as
referred
HDPE
the term refers to acrylonitrile
that is
polymerized with styrene
AN films,
or methyl aery late.
coatings,
and semirigid containers
are cleared for use only for single-
ABS
use food-contact surfaces. They
Poly(acrylonitrile-butadiene-styrene) copolymer. Heat distorts
it
Maximum continuous
service temperature is 165°F. ABS
at 200°F.
is
monomer. Usually,
have not been tested
120°F.
for
use above
AN films are used prima-
rily in the
pharmaceutical indus-
try.
resistant to acids, bases, fats,
and
oils.
It
does not
vents and yellows
sunlight.
for
if
resist sol-
exposed
to
ABS has been cleared
food use with
all
foods except
those containing alcohol and
those subjected to thermal processing.
It
can be used with foods
and stored at room
temperature, and stored refrigerthat are filled
ated or frozen.
Acetyl tributyl
citrate,
a deriva-
ATBC is used
in flexible packaging films
and
has been cleared for use as a plasfood contact surfaces of
resinous and polymeric coatings
and paperboard for
use with fatty foods. It has been
sanctioned by the FDA and falls
in paper
into the "relatively harmless" toxicity
category as a consumable
chemical. Estimated daily
human
intake from current uses of plastic
film
is
around 0.0008 milligrams
per kilogram of body weight.
ATBC is considered safe at this
level.
manufactured
there
is
like cellophane,
is
but
an additional reaction
that includes acetic anhydride.
It
deformed by heat, acids,
and
bases,
some solvents but is
resistant to fats and oils. It builds
up static. Maximum continuous
is
easily
CA is
175°F.
tive of citric acid.
and
Cellulose acetate. This material
service temperature for
ATBC
ticizer for
CA
Cellophane
Regenerated cellulose-based
ible
is
flex-
packaging material. Cellulose
dissolved in sodium hydroxide,
then extruded into an acid-salt
bath to produce filaments of regenerated cellulose.
It
can be
coated with Saran for use with
oily or greasy products. Cello-
phane was introduced
in the
1920s as a bread wrap.
It is
semi-
moisture-proof and heat-sealable.
The
heat-sealing range
300°F. Cellophane
is
is
200
to
flammable.
HDPE
EVA
2.
Ethylene-vinyl acetate copolymer.
percent to 15 percent vinyl
High-density polyethylene (see
EVA is a
alcohol can be used with aque-
PE).
ous acid and nonacid foods
tinuous service temperature of
rial
flexible
packaging mate-
formed from low-density poly-
ethylene (PE) and vinyl acetate.
more
is
flexible
permeable
EVAs
to
It
than PE but more
are unstable at high temper-
EVA is
tures.
low tempera-
cleared for use with
foods and for treatment with
fatty
irradiation as a sterilant (up to 8.0
megarads
total),
heat-sterilized.
so
so
It is
oil;
dairy oil
in water emulsions; beverages;
and
fats
oils;
solids with free surface
oil;
and
foods that are refrigerated or
treatment.
very stretchy,
to
at 140°F.
It is
It
will build
and
used
for
up
milk
fats
static.
and
oils.
HDPE is
jugs, cleaning sup-
ply bottles, and trash bags.
High-oxygen-barrier
An ethylene content of 20
40 percent,
to
60
cent vinyl alcohol
for
160°F but distorts
resistant to moisture, gases, acids,
no thermal
frozen-stored with
3.
HDPE has a maximum con-
bases, solvents,
moist bakery products and dry
need not be
it
can be used as a shrink wrap.
it
with free surface
low-moisture
water and gases.
atures but stable at
An ethylene content of 55
food use with
80 per
approved
to
is
all
foods ex-
polymers
Polymers used
to prevent
almost
all
oxygen
als
include vinyl alcohol, vinyli-
transfer.
These materi-
EVOH
cept those containing alcohol
Ethylene vinyl alcohol, a copoly-
and those which
mer
water-sterilized, hot-filled, or
are not melt-processable, so they
pasteurized above 150°F.
are
with another organic polymeric
This material can be used on
such as PVDC, EVOH, or AN.
phase (polystyrene or nylon).
refrigerated or frozen ready-
EVOH can be formed into films,
prepared foods to be reheated
It
and ethylene.
may be modified by blending it
of vinyl acetate
sheets,
and
rigid containers.
in the container at the time of
It
and gases (such
dioxide).
as
has been tested and has been
shown not
EVOH has excellent
it
to release substances
exceeding 0.15 milligrams per
can be used with a wide variety of
square inch of food-contact
foods. There are three types of
surface at 212°F.
into
copolymer forms
HP polyester
High-performance PET. This material
carbon
chemical barrier properties, so
made
use, provided the specific film
provides an excellent barrier to
flavors
are boiling-
dene chloride, and acrylonitrile.
Pure polymers of these substances
has a melt point of 275°F
and can be melt-blown and hotfilled. The final container is yellow but has excellent barrier
properties. For instance,
it
retains
carbon dioxide in soda.
EVOH:
1.
An ethylene content of 55
FSL
percent to 30 percent vinyl
Food-simulating liquids. These
alcohol can be used with acid
are substances
aqueous and nonacid aqueous
foods with no free surface oil;
simulate the possible reactions
dairy oil in water emulsions;
oil-free beverages;
bakery prod-
and dry solids with no free
surface oil; and foods that are
ucts
hot-filled or pasteurized at
150°F or
less,
and room-temper-
which
are
used
to
between food and materials with
which they come into contact.
The chemical characteristics of
FSLs are specific, so a particular
food
may be
simulated with sev-
eral food-simulating liquids in-
cluding distilled water, 3 percent
ature-, refrigerator-, or frozen-
acetic acids (acid foods), 8 percent
stored.
or 50 percent ethanol (alcohol-
containing foods), and n-heptane
(fat-
or oil-containing foods).
Hydrogen peroxide
An oxidizing agent used
for cold
packaging such as
sterilization of
films and bottles before filling
them with hot or sterilized food.
Residual hydrogen peroxide
limited by the
FDA to
is
0.1 parts
per million (ppm) after packaging
(FDA 21CFR
178.1005). Hydro-
gen peroxide is permitted as a
sterilant for PET, olefins, and
EVA.
LDPE
PE
Low-density polyethylene (see
PE).
Maximum continuous
vice temperature
is
distorts at 104°F.
LDPE
to
140°F;
Polyethylene. Polyethylene
ser-
it
heat-
is resistant
moisture vapor, acids, bases,
and
fats
and
oils.
It
sistance to solvent
static.
LDPE
is
has poor
re-
and builds up
used primarily
packaging films and
PET
for
for bread-
wrapping bags.
Polyethylene terephthalate, a
is
cleared for food contact surfaces
polyester resin used for high-im-
an "olefin polymer." The structure of this polymer is relatively
pact resistant containers.
loose, so
barrier for both flavors
as
rier
than
it is
a less effective bar-
PVDC
or
PVC.
It
was
carbons
introduced in the food industry in
PET is
PE can be produced by
two processes: low pressure pro-
some
the 1950s.
duces high-density PE, while high
pressure produces low-density
OPP
PE. Low-density
Oriented polypropylene.
OPP
has
and oxygen barrier
characteristics and protects against
good
light
moisture.
It is
clear but will ac-
OPP can be
cept printing ink.
manufactured
flexible.
It
to
be semirigid to
can be overlaid with
metalized polyester
or colored).
trolled
It is
(silver, gold,
used
for con-
atmosphere snack foods in
melt-blown,
clear.
It is
a
PE
is
strong
good moisture
and
barrier
but a poor oxygen barrier, and
will heat-seal to
up
static
self.
250
Its
itself.
and tends
it
PE builds
to cling to
heat-sealing range
to 350°F. In general
is
PE
it-
from
is
It is
poor resistance
It
to bases
fats
but has
and
solvents.
will not tolerate continuous boil-
ing in water.
Maximum continuous
service temperature
and heat
used
for
tion in
foods containing free
These containers are more expen-
oil that are
if
the material
is less
than 0.02-inch thick, or hot-filled
if
the ma-
between 0.004- and
0.02-
baby bottles. Recent
100 times) of polycarbonate
bottles for school
to
a total of 6.0 megarads. Certain
polymers have restricted uses,
legisla-
plastic
milk programs and
to 275°F.
products such as juice-based
distortion occurs at 180°F; maxi-
mum continuous service temperature
is
is
used
used
es-
and
beverages and tomato sauce. Heat
212°F. High-melting
PET
for rigid trays of the
type
for
items.
It
TV dinners
or entree
can be heated in a micro-
pecially with respect to tempera-
wave
ture.
350°F for 30 minutes. There has
or in a conventional
oven
at
been a moderate amount of concern that additives from these
may
ticularly
a
half-gallon milk containers for retail
use.
up
At boiling temperatures,
but they can be used for hot-
trays
New York allows refill (up to
bottles, boil-
deform badly. Modified PETs
distor-
tion occur at 275°F. This material is
soda
have melt points of 253
for irradiation sterilization
and
liners,
been tested and approved for use
with aqueous acid and nonacid
inch thick. PE has been cleared
stable to acids
box
bottles will shrink 30 percent
terial is
very clear and break-resistant.
PET is used
boiling.
and
It is
fats.
not for cooking. Copolymers have
food are chips in "bubble packs"
It is
mold.
and
cleared for use for packaging but
or pasteurized at 150°F
PC is a rigid plastic.
oils
and microwave food trays. The melting
point of unmodified PET is below
vent development of rancid
Polycarbonate.
and
in-the-bag pouches,
filled
PC
not transparent.
resistant to acids, bases,
solvents,
cereal
sive,
airline peanuts.
and hydro-
mouthwash, pourable
dressings, edible oils, and peanut
butter. Monolayer films will hold
a crease, and are heat-sealable and
transparent. The film is used for
over 212°F
Examples of these snack
It is
difficult to
heat-sterilized at temperatures
vor.
provides a good
it
for soda,
which air has been flushed out
and replaced with nitrogen to prefla-
(fat).
When
migrate into foods, par-
if
the trays are reused in
microwave oven.
Plasticizers
PP
acid or nonacid foods and bever-
Substances used to increase the
Polypropylene. Polypropylene
ages containing no
was introduced
foams are used
flexibility of
polymeric
(plastic)
They prevent formation of
some of the bonds between polymer molecules and make the
films.
Common plasti-
films less rigid.
cizers include dioctyl adipate
(DOA), which
used with PVC;
butylated hydroxyanisol (BHA),
is
which is used with polystyrene
and styrene; low-density polyeth-
in the 1950s.
It is
PS
beverage
very transparent but cracks and
cups, egg cartons, meat trays, and
low temperatures (15°F).
It was used successfully in the
mid-1960s as a copolymer with
PE but was eventually replaced
by plain PE for bags. It is more
rigid, stronger, and lighter than
preparation cups for instant foods
breaks
PE.
at
It is
resistant to water vapor,
ylene (LDPE); high-density poly-
and solvents,
some
polypropylenes
and
are re-
ethylene (HDPE); and high-mo-
sistant to
hindered phenols,
or oils.
fat
for hot
grease, acids, bases,
high temperature. Heat
such as noodles and soups.
PVC
Polyvinyl chloride.
manufac-
It is
tured by polymerizing vinyl chlo-
monomer. Plasticizers must
be added to give it flexibility.
The structure of this polymer is
relatively tight, but some air will
ride
PVC has
distortion occurs at 113°F; maxi-
pass through
used with ethylenevinyl acetate (EVA). Other ap-
mum continuous service tempera-
distortion temperature of 165°F
proved plasticizers are
irradiation sterilization
lecular- weight
which
are
listed in
The Food Chemical News Guide
(pp. 328.1-328.4).
Polyamide
ture
is
100°F.
PP
is
cleared for
up
to 1
megarad total. Polypropylene is
used for yogurt containers, margarine tubs, and bottles for some
pourable foods such as syrup.
(Nylon-6, Nylon-12)
A flexible packaging material
made from amino
ized vegetable
acids or dimer-
oils.
Polyamides
good oxygen and water barriers, but they have low melting
points. Polyamides are approved
for use as food contact coating on
materials not to exceed room temperatures, as a component of paperare
board, as sealing gaskets for food
containers,
and
as film coatings.
Certain polyamides are approved
for higher
tions.
temperature applica-
Nylon-66 has a very high
melting point but
heat-seal.
at
400°F;
is difficult to
Heat distortion occurs
maximum
service temperature
continuous
is
175°F.
and a
it.
maximum continuous
cause
its
shrink and melt points
are so low,
PVC can be used to
shrink wrap foods which tolerate
very
little
heat.
It is
PS
fats,
Polystyrene, a rigid or flexible
for
packaging material. PS
red meats because
It
heat distorts at 170°F.
It is
resis-
tant to water,
oxygen (but not
bon
and
weak
dioxide),
car-
acids, bases,
damaged by solvents and alcohol. PS
films are approved for irradiation
sterilization up to a total of 1
megarad. PS can be formed into a
foam that is less brittle than solid
PS film. PS can be foamed using
fats
and
oils,
but
it is
n-pentane, isopentane, or toluene
as the
"blowing agent"; the use of
chlorfluorocarbons (CFCs) has
been discontinued in the manufacture of items used by the food
service industry. PS foam is approved for food use with aqueous
ser-
vice temperature of 150°F. Be-
water, acid, bases,
is brittle.
a heat-
and
oils.
resistant to
some
solvents,
PVC is approved
use as the film to wrap fresh
enough
air to
it
allows
pass through the
package to make the meat pig-
ments "bloom" bright
red.
PVC is
Prior Sanctioned for use in general
food contact applications.
The
heat-sealing range
200
to 350°F.
megarad.
from
PVC is approved for
irradiation sterilization
1
is
up
to
10
PVDC
Susceptor
Polyvinylidene chloride, a co-
A thin metalized film joined to a
For more information contact the
polymer of vinylidene chloride
and vinyl chloride or methyl ac-
container (often paperboard) with
Society of the Plastics Industry,
an adhesive.
1275
PVDC was
rylate.
to protect
Plastics Industry).
PVDC
to
pizza or to help generate enough
heat to cause popcorn to pop.
Susceptors attain temperatures of
450
is
to 500°F
in surfaces of materials that con-
and
direct contact
food package
come
and aqueous
fatty
a
The
heat distortion temperature of the
polymer
is
113°F,
at
160°F.
is
PVDC films
soften
250°F, so they can be used with
food that
sarily
is
boiling, but not neces-
with high-sugar or high-fat
may get much hotter
than 212°F. PVDC and PVC can
foods that
be copolymerized
material, causing
them
to migrate
generation susceptors used
susceptors are currently being de-
veloped; they will use nickel, cobalt, iron,
and
stainless steel to
improve the susceptor's heating
capacities.
and the maxi-
mum continuous service temperature
plasticizers in the packaging
or paperboard. Second-generation
tightly together that very little gas
or water can get through.
volatilizing the adhesives
aluminum-coated polyester film
foods.
The copolymerization results in
film with molecules bound so
and have the poten-
into the food product. First-
in
with dry foods, and
paperboard coating in contact
with
to
microwaveable foods such as
tial for
gaskets, coverings that
is
cause browning or crisping of
cleared for use as a base polymer
tact food, including
purpose
"heat up" in the microwave oven
invented in
equipment from
outdoor elements. After World
War II, it was approved for food
packaging, and it was Prior Sanctioned in 1956 (Society of the
1941
Its
to
produce a
VCM
Vinyl chloride monomer.
PVC
can have residues of vinyl chloride
monomer (VCM)
in the fin-
ished plastic film. These levels
have been reduced
to insignifi-
cant amounts since the late 1970s.
family of flexible "Sarans."
The Codex Committee on Food
Additives and Contaminants has
Sarans are clear and have excel-
proposed guideline levels of
lent barrier properties. Their
lppm
heat-sealing range
400°F.
is
from 280 to
PVDC is resistant to
gen, water, acids, bases,
vents.
oxy-
and
sol-
for
and 0.01
food.
VCM in PVC packages
ppm
for the
monomer in
K Street N.W., Suite 400,
Washington, D.C. 20005;
(202)371-5200.