Transfer of molecules from the product to the external environment through the package or from the external environment through the package, to the product
Permeability
Movement of molecules contained by the product into, but NOT through the package
Sorption
Movement of molecules originally contained by the package, into the product
Migration
Coffee/Tea tasting like the Styrene cup is a results of _________.
Migration
Orange juice scalping limonene into Polyethylene is a result of ________.
Sorption
Give an example of when Migration caused a problem:
When coffee or tea begins to taste like plastic due to migration from the styrene cup to the product
Why do you need to determine the best barrier for your food product? Why not just use the highest barrier available? Why pay for more barriers than you need?
You need to determine the best barrier for your food product because it is important for shelf life extension and maintaining fresh quality. You shouldn't just use the highest barrier all the time because its more expensive and may not be needed. You don't want too much of a barrier because you may be harming the product by keeping some factors out.
Permeation occurs in ___ steps.
3
3 Phases of permeability:
1) Sorption2) Diffusion 3) Desorption
What happens in Phase 1 of permeability:
Sorption, where the gas/vapor (permeant) is absorbed into the polymers surface
What happens in Phase 2 of permeability:
Diffusion, where the permeant diffuses through the polymer (it permeates from the environment, through the package)
What happens in Phase 3 of permeability:
Desorption, the permeant desorbs/out gasses from the opposite side of the polymer. It makes it to the product. Doesn't happen too much with good barriers
In permeability, the distance from X = 0 to X = L represents what?
The distance between package walls
TRUE OR FALSE: Pearmeat is free to move in all directions
TRUE
TRUE OR FALSE: In the permeability diagram, if the concentration was equal, the line would be tilted
FALSE, it would be straight
What 2 things drive Net Flux:
Pressure difference and concentration difference
How fast molecules are moving deals with ______, while how many deals with _______.
Diffusion, solubility
TRUE OR FALSE: Net flux wants to reach equilibrium
TRUE
Permeation rate can drastically be affected by the "driving forces" as well as what 2 things?
Temp and RH
Permeation can lead to which consequence?
Dehydration
What % of all food products demand barriers to gas, flavors and odors?
80%
P =D * S is the equation for:
Permeability Coefficient
Measure of how rapidly penetrant molecules are moving through the barrier, in the direction of lower concentration or partial pressure
Diffusion Coefficient, D
The amount of transferring molecules retained or dissolved in the film at equilibrium conditions
Solubility Coefficient, S
Concept of moving from area of higher concentration to lower concentration or vice versa
Thermodynamic Equilibrium
TRUE OR FALSE: It is easy in packaging to look at the thermodynamic equilibrium in both gas and liquid phase
FALSE
For thermodynamic equilibrium in the gas phase, you should use what?
Partial pressure
For thermodynamic equilibrium in the liquid phase, you should use what?
Solubility
A solution is formed when what 2 things mix?
When a compound (oxygen) mixes with a liquid (water)
Which law describes the relationship between concentration of a liquid and concentration in the gas phase?
Henrys law
Which law would be a good law to use for ideal solutions such as Oxygen or Carbon Dioxide?
Henrys law
What are 2 exceptions to Ficks "steady state" law:
Nylon and EVOH
Which law describes how the concentration of molecules moving through the polymer end up equal over time?
Ficks "steady state" law
Fickian behavior exhibits a ________ state.
Steady
J = -D (change in C/change in x) is the equation for:
Ficks first law, steady state