Lecture 7 Flashcards
What is the purpose of food packaging?
To provide protection to the food from microbes, physical stress and oxidation
How to control the internal environment:
Control the
- temperature
- humidity
- amount of oxygen coming into the product
through the packaging material and modified atmosphere conditions
Role of packaging material
Where the properties of the packaging material and it’s functioning come from which give it
- protection
- consumer friendliness
- economic feasibility
Benefits of a strong package and how to make a package strong?
Strong package-Is a strong barrier to oxygen, microbes and physical stress
How to make it strong-use the appropriate polymer with the largest weight and crystallinity (HPPE)
Temperature where rigidity and flexibility begin to change
- Melting point:
- Glass transition point: temp at which the molecules in the material begin sliding
How come thermoplastic polymers will never reach the gas phase?
Because they are a number of them that are entangled with one another which provide a strong degree of entanglement and van der walls forces to keep them from separating so extensively.
Difference between high density polymers and low density polymers.
HDPE: are not so structurally branched
LDPE: are more structurally branched
Purpose of stretching melted film in multiple directions before it cools?
Provides strength, barrier properties and creates a more favorable appearance.
Heat sealing process:
-Two layers of material are fused together which contain polymers that are liquified through the use of heat and then fused together through the use of pressure and time and then cooled to form one shape. The application:
Extrusion blow processing:
polymer is melted and it enters a shaped container, it touches the walls of that shaped container and takes the shape of that container known as a blow mold cools and becomes that shape.
