LAB – FOOD PACKAGING
FSTC 311
Activity #1- 15-20 minutes
Application: Beverage container
Product: Carbonated beverage (soft drink)
•
Three different classes of materials (metals,
inorganic glass, and polymers) may be used
to manufacture beverage containers.
•
Goal: Discuss materials properties and select
the best package (material) for a
carbonated beverage soda
Carbonated Beverage Containers –
Selection Criteria

1.
2.
3.
4.
5.
The material used for this application must
satisfy the following constraints:
Provide a barrier to the passage of
carbon dioxide, which is under pressure
Be nontoxic, unreactive with the
beverage, and, preferably, recyclable
Be relatively strong and capable of
surviving a drop from a height of
several feet
Be inexpensive, including the cost of
fabrication
Be capable of bring produced in
different colors and/or adorned with
decorative labels
Callister and Rethwisch (2009)
(a) Activity # 1

Fill out the table with the relative advantages and
disadvantages of each class of material for this
application.
(b) Activity # 1

Consider properties such as weight, strength,
reusability/recyclability, ability to keep the product
fresh, and any others that are important for the
application.
Material
Weight
Strength
Reusability/recycla
bility
Ability to keep
product fresh
Deformation
behavior
Resistance to high
and low
temperature
Corrosion problem
Cost
Metal
Glass
Polymer
Aluminum
Silica
Light
Adequate
No reusable. Highly
recyclable but must
be remelted and
reshaped
Heavy
Strong
Reusable (after
cleaning and
sterilizing).
Recyclable but must
be remelted and
reshaped.
YES - inert material
thus does not react
with content
PETE or PET
(Polyethylene
terepthtalate)
Light
Adequate
Not reusable.
Recyclable but must
be remelted and
reshaped.
YES - good
protective barrier
Ductile - will
withstand some
deformation before
breaking
OK
Brittle - will fracture
if surface is
scratched.
OK
YES although not as
good as metal or
glass.
Permeability
problems.
Ductile - will
withstand some
deformation before
breaking
OK
For low pH - not
suitable for wine or
fruit juices without a
protective coating.
NO
NO
High
Intermediate-High
Lower
Materials Science and Engineering. An Introduction by William D. Callister, Jr. Sixth Edition, John Wiley & Sons, Inc. New York.
The Coming of Materials Science by R. Cahn, 2001, Pergamon Press.
(c) Activity # 1

Provide a recommendation for a package of the
product.
PACKAGING AND THE
ENVIRONMENT
The problem with plastics
http://ensia.com/wp-content/uploads/2015/07/feature_sustainable_plastic_main760x378.jpg
“Even though people feel like they would like
to use less plastic rather than more, the fact
of the matter is that plastics are modern
materials that make cars lighter, purify water
and add tremendous benefit to health and
security applications.” — Marc Hillmyer,
director of the Center for Sustainable
Polymers at the University of Minnesota in
Minneapolis.
Activity # 2 – 15 minutes


Packaging is often criticized for creating waste.
List two different ways in which packaging reduces
waste.
Activity # 3 – 15 minutes


Your company wishes
to package their
butter in "paper
and/or paperboard
only".
What is the optimum
packaging system
you can recommend
to them?
Common uses for HDPE, PP, PVC, PS and PET,
along with a material property which is
important for that use.
Material
Uses
Material property
HDPE
Bottles, supermarket
bags
Stiffness, tensile
strength
PP
Thermoformed tubs
Good barrier
PVC
Shrink film for meat
Grease resistance
PS
Bags for fresh
produce
Clarity, permeability
PET
Beverage bottle
Strength, good
barrier properties
PC
Boil in bag
Temperature
resistance, clarity
Activity # 5 – 15 minutes
A nut packager complained regarding the off flavor
developed in one lot of his packages.
 This is what is known about the package:
a) the residual oxygen levels were checked and
found satisfactory;
b) the barrier properties of the packaging
material were found to be within specification;
c) the package was transparent.
What went wrong?
What could be done to reduce the problem appreciably?
Activity # 5 – Nuts packages
Activity # 5 - Answer

The peanuts contain oil (fat) and are sensitive to
oxidative reactions due to the exposure to light.
https://sp.yimg.com/ib/th?id=JN.SbC8ia5zZ61PwRFy1yYuxA&pid=15.1&P=0&w=300&h=300
Activity # 6 – 15 minutes



A packer of sausages
complained that the
packaging material lacked
PVDC (polyvinylidene
chloride) coating as
specified.
His sausage packages were
ballooning in the store.
This latter fact was indeed
verified.
http://blogs.houstonpress.com/eating/football.jpg
Activity # 6

However, tests on
packaging material
involved confirmed the
presence of PVDC.
http://blogs.houstonpress.com/eating/football.jpg
1.
2.
What caused the
ballooning of the
sausages?
How can this
problem be
solved?
Activity # 6 - Properties of PVDC
1.
2.
3.
4.
5.
Pure PVDC — stiff film which is unsuited to food
packaging
Only PVDC/PVC copolymer is used in food packaging.
Plasticizers: also required.
Very soft transparent film with some haze
Has one of lowest permeabilities to water and vapors of
all
Plastic films
1. Heat sealable
2. Resistant to fats and oils
3. Very expensive to produce
4. Tendency to cling - cling wrap (advantage)
5. Difficult to use in machines
Activity # 6 -Facts
1.
2.
PVDC is a good barrier
for oxygen and other
gases
A typical package for
some meat products is
a laminate of
polyester/polyethylene
with PVDC coating or
use of an inorganic
adhesive.
Activity # 6
What caused the ballooning of
the sausages?


The ballooning was
due to bacterial
activity within the
meat product,
generating gas.
The gas was trapped
within the barrier
package.
How can this problem be
solved?
Eliminate the PVDC
barrier thus permitting the
gas to escape through the
package wall.
The gas generation may
still continue, but may be
no longer observable.
What is the problem with this solution?
Activity # 6 - Problem with this solution
It does not resolve the serious causes
(improper processing)
Activity # 7 – 15-20 minutes


Evaluate the package of one food product and
provide a reasoning for the choice of packaging
(e.g., shape, material, color, functionality, etc.).
Use the packaging matrix to support your answers.
Environments
Protection
Utility/Convenience
Ambient
Human
FUNCTIONS
Physical
Communication
FUNCTIONS/ENVIRONMENT GRID FOR EVALUATING PACKAGE PERFORMANCE
Activity # 8

D = 2-2.5 dp; cylindrical container
D = dp/1.5 for a frozen product
What change in microwavable package size should be made
when adding salt to water?
Dielectric constants

e’ = permittivity or dielectric constant
 Ability
of a material to store microwave energy
 Water (e’ = 77.4) and high moisture content foods =
higher e’
 Foods: 40 < e’ < 70
 Water versus ice:
 Ice
has very low ability to store energy (e’ = 3.2 )
 This means that ice is transparent


Most of the incident energy is reflected back
Ice does not absorb microwaves nearly as well as water (<<<
e”)- this means it actually heats up less.
Dielectric constants

D = 2-2.5 dp; cylindrical container
D = dp/1.5 for a frozen product
e” = dielectric loss factor
 Ability
of a material to dissipate microwave energy
into heat
 High e” (~ 20-30) = lossy material (eg, ham, salted
products)
 e” = 0 = nonabsorbing medium
 Higher e”, the lower the penetration depth

Both depend on moisture content, temperature, and
composition of foods, and frequency of the oven.
Activity # 8

D = 2-2.5 dp; cylindrical container
D = dp/1.5 for a frozen product
What change in microwavable package size should be made
when adding salt to water?
Activity # 8



The higher the salt
content, the lower the
penetration depth
~ 1.7 cm to 0.20 cm
Container (diameter)
should be smaller
D = 2-2.5 dp
Salts act as conductors in electromagnetic field – decrease e’ and increase e”
Activity # 8

D = 2-2.5 dp; cylindrical container
D = dp/1.5 for a frozen product
Comment on the difficulty of rapidly thawing foods in a
microwave oven.
Comment on the difficulty of rapidly
thawing foods in a microwave oven.
◦
◦
◦
Microwave energy will go through the frozen food
without absorbing much energy (that’s why the low e”).
Hence, there is need to use the defrost cycle first to
allow for enough time to uniformly heat the food.
Liquid water will absorb much of the energy as heat
and that is why the reduced depth of penetration.
Activity # 8

Does the “map” illustrate the problem with microwavable
bread items?
Activity # 8


e’, e” of bread are very
low due to the low
moisture content
Higher penetration depth
Activity # 8

What would be the impact (if any) of adding a coat of
butter to the bread?
e” = 0 = nonabsorbing medium
THURSDAY, OCT0BER 29
Package design