Modified Atmosphere Packaging

Question 1

What is “MAP?” What is its purpose?

Answer 1

gas barrier materials (selective permeability) to modify gaseous environment

-> extend shelf life

Question 2

How does MAP extend shelf life?

Answer 2

alter gaseous environment:

• > slow microbe growth
• > slow respiration
• > retard enzymatic spoilage

Question 3

the principles of MAP are based on:

Which is more stable/precise?

Answer 3

CA, MA storage

CA/MA is more stable/precise (cannot control package or environment conditions once exits factory)

Question 4

The CA/MA inside the package is maintained by selective ____ of ____ into the package, and ____ out of the package.

Answer 4

diffusion
CO2
oxygen

Question 5

Equilibrium is a balance between ___ ____ and ___ ____

Answer 5

product respiration; package permeation

Question 6

What is critical to consider for MAP? Why?

Answer 6

temperature

affects both respiration and permeability rates

Question 7

What are the aims of MAP concerning the gaseous environment?

Answer 7

reduce oxygen levels
increase CO2 levels

then maintain

Question 8

What is the gaseous environment comprised of?

Answer 8

O2
CO2

N (filler)

Question 9

What gas can be used to further improve CA?

Answer 9

CO (carbon monoxide)

Question 10

What are some uncontrolled examples of MA?

Answer 10

airtight cold storage rooms
film/wrap/bags
PE liners in shipping containers
pallet shrouds
vents
waxes
plastic with diffusion windows

Question 11

2 stages of MAP or MA:

Answer 11

1. MA Generation

2. MA maintenence

Question 12

How is the MA generated? (2)

Answer 12

1. active process (commercially): GAS FLUSH: fast control of resp/ethylene, vacuum to remove toxic gases
2. passive process: produce respiration (slow, some quality loss)

Question 13

how is MA maintained?

Answer 13

selective permeability

Question 14

What are various gas barriers present in the system?

Answer 14

commodity’s dermal system (natural skin)
coating (wax, film)
package
room

Question 15

What causes the changing of gas atmosphere in passive process?

Answer 15

produce respiration: consume O2 (deplete), release CO2

Question 16

True/false: With equal permeability, oxygen and CO2 flow rates are equal.

Answer 16

False

O2 = 16/10 CO2

Question 17

What happens in a package with NO permeability?

Answer 17

CO2 cannot exit (accumulates), O2 depleted (O% oxygen)

• > puffing of package
• > fermentation

Question 18

What happens in a package with equal permeability?

Answer 18

no change in gaseous environment

Question 19

What permeability can maintain active MAP?

Answer 19

deltaC for O2: 16%

for CO2: 10%

Question 20

What plastic has the lowest permeability?

Answer 20

saran (PVDC)

Question 21

What plastic has the highest permeability?

Answer 21

LDPE (low density polyethylene)

Question 22

What factors need to be considered with MAP?

Answer 22

Commodity factors (RQ, resp rate, type, maturity, quantity)
film/package factors (type/structure, thickness, SA)
environmental factors (temperature)

Question 23

gas flux should be proportional to:

Answer 23

difference in concentration x permeability

Question 24

constant K depends on:

Answer 24

surface area, thickness of film

Question 25

respiration flux =

Answer 25

respiration rate x mass

Question 26

What effect does temperature change have?

Answer 26

affect respiration rate, permeability

Question 27

What happens if respiration is greater than permeation?

Answer 27

O2 will be depleted
accumulation of CO2
causes damage (cannot respire)

Question 28

What happens if permeability is greater than respiration?

Answer 28

more O2, more CO2 released
lose MA (ineffective)

Question 29

What are the advantages of edible coatings? What are some examples?

Answer 29

provide MAP
moisture barrier
biodegradeable

methylcellulose, whey films

Question 30

Active packaging is:

Answer 30

packaging with additional functions:
MAP
Moisture barriers
+ additional functions (antibacterial, antifungal, etc)