Modified Atmosphere Packaging Flashcards
What is MAP?
modified atmosphere packaging:
selective permeability material package so that air surrounding the food has different composition than outside
What is the difference between CA and MAP?
controlled atmosphere: continuous control (adjustable, stays constant)
mod. atmosphere packaging: depends only on package properties, no further control once package is sealed
Why are MAP becoming more in demand? (4)
natural
retains quality
longer shelf life
convenience
How can O2 damage food?
oxidation
discoloration
microbes -> decomposition
damage from insects/vermin
The effects of O2 will cause loss of: (4)
freshness
quality
taste/flavor
nutrition
Advantages of MAP: (5)
- Longer shelf life (can market more places, make bigger quantities, less shelf-reloading)
- better use of labor/equipment
- less transport $$
- less storage $$
- sales enhancement
What positive impacts does increased shelf life have? (3)
less shelf re-stocking
increased market areas
can buy/manufacture larger quantities
Disadvantages of MAP: (5)
Cost (package, equipment, films, gases, QC...) slower throughput of packages leakage (package failure) secondary spoilage problems dangerous organisms growth??
Methods of atmosphere modification: (4)
vacuum packaging
gas packaging
gas absorbents
gas generators
What is vacuum packaging?
removed all/most air inside package (without adding another gas)
remove air -> seal
advantages of vacuum package: (2)
longer storage life (up to 5x as long as refrigerated food)
no freezer burn
complete barrier
_____ is the material used for vacuum packaging
laminated films (strength + barrier properties)
vacuum packaging machines: (3)
chamber vacuum
belt vacuum chamber
thermoform-fill-seal
forms of vacuum packaging:
transformed VP trays
skin packaging
The materials used for VP trays:
Top web + tray (same construction)
Outer: PA or PET
middle: PVC or PVDC coated
inside: LDPE or EVA or Ionomer
the materials used for vacuum skin packaging:
PVDC coated
ionomer (Surlyn)
In vacuum packaging, surlyn is often found as the ____ layer
innermost
3 forms of myglobin and their appearances;
myoglobin (dark red)
oxymyoglobin (bright red)
metmyoglobin (brown)
Conversion between forms of myoglobin happens due to what reactions?
oxidation, reduction
oxygenation, de-oxygenation
The major difference between metmyoglobin and the other myoglobins:
Fe is oxidized (Fe3+, not Fe2+)
T/F: meat with a purple appearance has been oxidized and is likely not fresh
False; purple meat is deoxymyoglobin
What is ‘meat blooming?’
oxidation
Which has greater OTR, VP packaging for fresh meat, or for processed meat? Why?
fresh meat packaging (lower barrier properties)
processed meat need even less O2 contact - for minimum degradation of nitrosomyoglobin
The VP films with lowest OTR (best barrier) are used for _____ meat, and ________
cured meat
O2-sensitive products
The greater the barrier properties of the vacuum package, the ______ the color of the meat
more purple (more myoglobin)
is the purple color from myoglobin permanent? What about the brown from metmyoglobin?
purple: NO - when package is opened (expose to air) quickly turns red…and eventually brown
brown: permanent (unless chemically reduce it)
What are some products that use VP?
fresh/frozen/process/cured meats fresh/frozen fish (+ breaded products) fresh/frozen poultry coffee some bakery good
Factors influencing shelf life of VP products: (5)
raw material quality (microbe count, pH) temp control hygiene control time prior to packaging film permeability
The higher the pH, the (faster/slower) the meat spoils in VP
faster
What meat has the longest shelf life in VP
beef
spoilage in VP meat is characterized by:
acidifying
greening
flavor (rancidity)
color/fat appearance
What is gas packaging?
displace air in package with new gas -> seal
methods of air replacement in gas packaging:
What equipment is used?
gas flushing (HFFS/VFFS) compensated vacuum (TFFS) passive modification (no equipment; takes place within sealed package)
Compare FFS gas flushing vs TFFS compensated vacuum
FFS: continuous and fast
but residual oxygen (2-5%)
TFFS: slower, but less residual oxygen (for O2 sensitive products)
T/F: FFS gas flushing is a better packaging system for foods sensitive to oxidation
false; TFFS is better (FFS has residual 2-5% oxygen)
characteristics of gas packaging films:
puncture resistant reliable seal! anti-fog properties CO2 permeability? low OTR low WVTR
Common mateials in laminates for MAP:
PET, PVDC, PE, PA, PVC, ionomers
Common laminate exterior materials for MAP: (3)
PET
PA
PVC
common laminate interior materials for MAP:
PE
PVDC
ionomer
Major gases in MAP: (3)
other potential gases? (4)
major: N2, CO2, O2
other: SO2, CO, N2O, Ar
Is CO2 inert?
No
Proprties of CO2:
not inert
bacteriostatic/fungistatic
anti-insect
fat/water soluble
For CO2 to be effective, it requires _____ minimum v/v
20%
Explain the antimicrobial actions of CO2:
- displace O2
- extracellular pH reduction
- intracellular pH reduction
- disrupt cell membrane/metabolism enzymes
- increases lag phase (longer shelf life)
Factors affecting the efficacy of CO2 as an antimicrobial: (7)
storage temp Aw gas concentration microbe type initial microbial load (#) additive contents film permeability
O2 is usually avoided in packaging, except in _____ (3)
fresh meat (for color)
fruit/veg (respiration)
anaerobe prevention
Properties of N2:
inert
no antimicrobial properties
filler gas
Compare the gas composition in packaging for meat vs poultry:
meat (beef/pork/lamb): high O2, 20%+ CO2, filler N2
poultry: NO O2! 20-40% CO2, mostly filler N2
What is the typical gas composition for processed meat packaging?
no O2, no CO2
entirely N2
Does bacon package contain oxygen or CO2?
No CO2
20-35% CO2
filler N2
typical gas packaging structure/composition for fresh meat;
lid + tray (PVC/tie layer/LLDPE)
20% CO2 (antimicrobial) + 80% O2 (maintain red)
What is the O2 content in packaging for fatty fish?
0 (oily fish + salmon, some white fish)
T/F: bakery products packagng usually contains high O2
False - 0% O2!
What is the predominant gas in bakery goods packaging?
CO2
The primary gas in produce packaging:
nitrogen
why is complete barrier film not desirable for produce?
makes anaerobic conditions -> respiration of produce cannot continue (CO2 builds up inside, causes fermentation)
If O2 is needed to maintain produce quaility, then what is the purpose of having MAP?
selective permeability -> creates specific % of CO2 and O2
maintain enough O2 for respiration, but low enough to SLOW it down (longer shelf life)
A film with _____ permeability is ideal for produce
selective/intermediate
What are gas absorbents?
chemical compounds added into package to alter atmosphere inside (absorb certain gases to alter composition)
O2 absorbents can be classified according to? (3)
material type
reaction style
reaction speed
material types of O2 absorbents?
inorganic - Fe powder, Na2S2O4
organic - ascorbic acid, catechol
enzyme - glucose oxidase
What is the action of glucose oxidase enzyme?
convert glucose into gluconic acid + H2O2
reaction style classes of O2 absorbents? (2)
self-reactive
moisture dependent
reaction speed classifications of O2 absorbents? (3)
immediate effect
general
slow effect
Formats of oxygen absorbents:
sachets labels cards scavenging films crowns/closures (top of lid)
What factors affect the type/size of sachet needed? (6)
Food form (size/shape/wt) Aw of food amount of O2 in food initial O2 in pack desired shelf life O2 permeability of package
advantages of O2 absorbents:(6)
nontoxic/safe extend microbial + chemical shelf life replaces additive/preservatives reduce losses ($) replace pesticides to prevent insect damage
Disadvantages of O2 absorbents (5)
need free air flow cause package collapse? flavor changes in high-moisture food consumer resistance more \$\$$
What is done to prevent package collapse with O2 absorbents?
combine O2 absorbent with CO2 generator
____ reacting types of O2 absorbents are used for baked/frozen goods
fast-reacting (SS)
What type of O2 absorbent is used for most foods?
standard iron type (ZPT)
describe the structure of a O2 absorbent package material (AGELESS OMAC):
outer: protective layer (PET/Nylon)
Gas barrier: Aluminum/EVOH)
O2 absorbent: (PP/PE + Fe type absorbent)
Heat seal layer (PP/PE)
O2 absorption will continue for longer with (higher/lower) RH%, and (higher/lower) temp
lower
lower
____ scavengers are often used for fresh produce
ethylene
What materials are used for ethylene scavengers? (3)
sachets: KMnO4 or activated charcoal (w/ Pd catalyst)
PE film with activated clay
What chemicals are used as CO2 absorbents? (3)
CaO
Ca(OH)2
NaOH
What is a type of gas generator used for antimicrobial properties?
ethanol vapor generators
Types of ethanol vapor generators and their functions:
Ethicap - increase ethanol
Negamold - increase ethanol, absorb O2
ethanol generators are commonly used for what products?
higher moisture cakes/bread
What is SO2 gas useful for?
antimicrobial
Describe the SO2 generation system
outer fibreboard carton
Ca-sulfite layer + organic acid layer -> SO2
How is SO2 generated?
organic acid + water
- > H ions
- > goes to outer film
- > reacts with Ca2SO3
- > release Sulfuric acid (& Ca)
- > release SO2 (& water)
____ gases can be used for ethylene removal, for ______(products)
halogen (KI, NaClO2) - for grape, pear
What is ethylene generators used for? What types are they?
ripening (green orange/banana)
ethylene derivatives, activated C, zeolite
example of CO2 generators:
What are they used for?
NaHCO3 + malic acid
persimmon, grape
