LAB – FOOD PACKAGING

FSTC 311

Application: Beverage containerProduct: 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

Activity #1- 15-20 minutes

The material used for this application must satisfy the following constraints:

1. Provide a barrier to the passage of carbon dioxide, which is under pressure

2. Be nontoxic, unreactive with the beverage, and, preferably, recyclable

3. Be relatively strong and capable of surviving a drop from a height of several feet

4. Be inexpensive, including the cost of fabrication

5. Be capable of bring produced in different colors and/or adorned with decorative labels

Carbonated Beverage Containers – Selection Criteria

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.

  Metal Glass Polymer

Material Aluminum Silica PETE or PET (Polyethylene terepthtalate)

Weight Light Heavy Light

Strength Adequate Strong Adequate

Reusability/recyclability

No reusable. Highly

recyclable but must be

remelted and reshaped

Reusable (after cleaning and sterilizing).

Recyclable but must be

remelted and reshaped.

Not reusable. Recyclable but

must be remelted and

reshaped.

Ability to keep product fresh

YES - good protective

barrier

YES - inert material thus does not react with content

YES although not as good as metal or glass.Permeability

problems.

Deformation behavior

Ductile - will withstand

some deformation

before breaking

Brittle - will fracture if surface is scratched.

Ductile - will withstand

some deformation

before breaking

Resistance to high and low temperature

OK OK OK

Corrosion problem

For low pH - not suitable for wine or fruit juices without a protective coating.

NO NO

Cost 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

http://ensia.com/wp-content/uploads/2015/07/feature_sustainable_plastic_main-760x378.jpg

The problem with plastics

“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?

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

Common uses for HDPE, PP, PVC, PS and PET, along with a material property which is important for that use.

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.

1. What caused the ballooning of the sausages?

2. How can this problem be solved?

http://blogs.houstonpress.com/eating/football.jpg

Activity # 6 - Properties of PVDC

1. Pure PVDC — stiff film which is unsuited to food packaging

2. Only PVDC/PVC copolymer is used in food packaging. Plasticizers: also required.

3. Very soft transparent film with some haze4. Has one of lowest permeabilities to water and

vapors of all5. Plastic films

1. Heat sealable2. Resistant to fats and oils3. Very expensive to produce4. Tendency to cling - cling wrap (advantage)5. Difficult to use in machines

Activity # 6 -Facts

1. PVDC is a good barrier for oxygen and other gases

2. 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?

It does not resolve the serious causes (improper processing)

Activity # 6 - Problem with this solution

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.

Physical Ambient Human

Protection

Utility/Convenience

Communication

Environments

FU

NC

TIO

NS

FUNCTIONS/ENVIRONMENT GRID FOR EVALUATING PACKAGE PERFORMANCE

Activity # 8

What change in microwavable package size should be made when adding salt to water?

D = 2-2.5 dp; cylindrical container

D = dp/1.5 for a frozen product

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

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.

D = 2-2.5 dp; cylindrical container

D = dp/1.5 for a frozen product

Activity # 8

What change in microwavable package size should be made when adding salt to water?

D = 2-2.5 dp; cylindrical container

D = dp/1.5 for a frozen product

Activity # 8 The higher the salt

content, the lower the penetration depth

~ 1.7 cm to 0.20 cm

Container (diameter) should be smallerD = 2-2.5 dp

Salts act as conductors in electromagnetic field – decrease e’ and increase e”

Activity # 8

Comment on the difficulty of rapidly thawing foods in a microwave oven.

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.

◦ 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