MAP (Modified Atmosphere Packaging) involves replacing the air in food packaging with a gas mixture to extend shelf life. Common gases used are CO2, N2, and O2. CO2 inhibits microbial growth. N2 acts as a filler gas and prevents package collapse. Low O2 inhibits aerobic bacteria growth. MAP shelf life extensions range from 50-400% depending on the food. Proper gas mixtures, packaging materials, and storage temperatures are required for each food type to maximize freshness and safety.

1. Speaker: Mahesh Chuadhary
M. Tech. Dairy Engineering
SMC College of Dairy Science
AAU, 388 110 Anand

2. INTRODUCTION
• During the last few decades there has been a trend towards an increased
demand for chilled food products with prolonged shelf-lives. Consumers
prefer pre- processed products that are fresh or fresh-like, convenient and
easy to prepare and without additives.
• MAP has become a commercial and economic reality in markets that have
a well-established and controlled cold chain.
• The use of carbon dioxide (CO2) to inhibit bacterial growth is not a new
technology. In 1877 Pasteur and Joubert observed that Bacillus anthracis
could be killed by using CO2.
(Valley, 1928)

3. -continued
• Showing an extended storage life for beef placed inside a cylinder filled
with a CO2 atmosphere.
• In the 1920s work at the Low Temperature Research Station in
Cambridge, UK, showed that storing apples in atmospheres containing
lowered levels of oxygen and increased levels of carbon dioxide could
increase their shelf-life.
• However, it is only in the last two decades that MAP(Modified
Atmosphere Packaging) has become a more widely commercially used
technology for the storage and distribution of foods.
Davies, 1995

4. MAP principles
• The principle of MAP is the replacement of air in the package with a
fixed gas mixture.
• MAP effectiveness depends on
1. Type of food
2. Initial quality of the raw material
3. Gas mixture, storage temperature
4. Hygiene during handling and packaging
5. Gas/product volume ratio
6. The barrier properties of the packaging material

5. MAP gases
• The three major gases used in the MAP of foods are oxygen (O2),
nitrogen (N2) and carbon dioxide (CO2).
• Usually for non-respiring products, where microbial growth is the main
spoilage parameter, a 30–60% CO2 split is used, the remainder being
either pure N2 (for O2 sensitive foods) or combinations of N2 and O2.
• For respiring products levels around 5% CO2 and O2 are usually used
with the remainder being N2 in order to minimize the respiration rate.

6. Carbon dioxide (CO2)
• CO2 is the most important gas in the MAP of foods, due to its
bacteriostatic and fungistatic properties.
• It has demonstrated that the growth inhibition of micro-organisms in
a modified atmosphere is determined by the concentration of
dissolved CO2 in the product.
(Devlieghere et al. 1998)
• The ratio between the volume of gas and the volume of the food
product (G/P ratio) should usually be between 2:1 and 3:1 (volume
of gas two or three times the volume of food). After the packaging
has been opened, the CO2 is slowly released from the product and
continues to exert a useful preservative effect for a certain period of
time, referred to as CO2’s residual effect.
(Stammen et al., 1990)

7. -continued
 The CO2 solubility could also alter the food water-holding capacity
and thus increase drip.
(Davis, 1998)
 Exudation pads should be used to absorb drip loss from products.
 The effect of CO2 on bacterial growth is complex and four activity
mechanisms of CO2 on microorganisms have been identified.
1. Effects on Nutrient Uptake and Absorption
2. Direct inhibition of enzymes or decreases in the rate of enzyme
reactions
3. Intracellular pH changes
4. Direct changes in the physico-chemical properties of proteins
(Farber, 1991;
Dixon and Kell, 1989;
Daniels et al., 1985; Parkin and Brown, 1982)

8. Nitrogen (N2)
• N2 is an inert and tasteless gas.
• Mostly used in MAP as a filler gas because of its low solubility.
• N2 is almost insoluble in water and fat and will not absorb into the
food product, and therefore counteracts package collapse as caused
by dissolved CO2.
• N2 is used to displace O2 from air in packages with O2 sensitive
products, to delay oxidative rancidity, and as an alternative to
vacuum packaging, to inhibit the growth of aerobic microorganisms.

9. Oxygen (O2)
 The use of O2 in MAP is normally set as low as possible to inhibit
the growth of aerobic spoilage bacteria.
 O2 (around 30%) in the atmosphere for lean fish species has been
used to reduce drip loss and colour changes.
 For respiring products O2 is included in the atmosphere to prevent
anaerobic respiration.

10.  Recently high levels (80–90%) of O2 have shown promising results
for extending the shelf-lives of selected fruits and vegetables.
 Originally, O2 was introduced into the packaging atmosphere of
selected products in order to reduce the risk of anaerobic pathogenic
bacterial growth, but this process has now been generally
discredited.
(ACMSF, 1992)

11. Fish and other seafood
• Fish and shellfish are highly perishable, due to their high aW, neutral
pH and the presence of autolytic enzymes which cause the rapid
development of undesirable odours and flavours.
• Inhibition and an increased shelf- life could be obtained through the
use of low storage temperatures combined with high CO2 contents in
the atmosphere surrounding the product by MAP.

12. -continued
• It is evident that MAP can extend the shelf-life of fish and
shellfish products.
• For raw fish an increase of 50–100% in storage life is
usually observed, and for cooked shellfish a shelf-life
extension of 100–200% can be obtained under ideal storage
conditions.
(Sivertsvik et al., 2002; Stammen et al., 1990)

13. -continued
• Vacuum packaging could also be an alternative to MAP for fatty fish
such as salmon, providing similar sensory shelf-lives when the
primary sensory spoilage parameter is oxidative rancidity. But the
microbial quality is still better under MAP conditions compared to
vacuum packaging.
(Rosnes et al., 1997; Randell et al., 1999)

14. CO2 in MAP packed Salmon
0
10
20
30
40
50
60
70
80
0 5 10 15 20
Storage time (days)
%CO2
■ MAP 1:1 emitter MAP 2 :1 MAP 1:1

15. -continued
 MAP can be combined with super chilling processes to further extend
the shelf-life and safety of fresh fish. In this technique, also known as
partial freezing, the temperature of the fish is reduced to 1–2ºC below
the initial freezing point and some ice is formed inside the product.
(Sikorski and Pan, 1994)
 A shelf-life extension of about seven days is obtained for super chilled
fish compared to traditionally ice-stored fish of the same type.
(LeBlanc and LeBlanc, 1992)

16. -continued
Figure: MAP (60% CO2: 40% N2) versus over-wrap air packaging on salmon fillets
stored at chill temperature (4ºC) and under super chilling conditions. Effect on
cooked flavour score, sensory evaluation (Sivertsvik et al., unpublished results).

17. Meat
• The two principal spoilage mechanisms affecting the shelf-life of raw
red meat are microbial growth and colour changes (oxidation of the red
oxymyoglobin pigment).
(Gill, 1996)
• Master pack is a convenient packaging technology with growing
interest in centralized preparation of retail-ready meat cuts because it
provides high quality ready-to-go products to consumers at lower cost.
• Aerobic spoilage bacteria, such as Pseudomonas species, which are
normally predominant on red meats, are inhibited by CO2 .
(Gill and Molin, 1991)

18. -CONTINUED
• Beef steaks are packed in master packages containing expanded
polystyrene trays overwrapped with polyvinyl chloride film under an
anoxic atmosphere containing 0.2% CO, 60.0% CO2 and 39.8% N2 or
0.2% CO/99.8% CO2 plus oxygen scavengers.
• After 28 days of storage at 1 and 4 0C, the meat quality was evaluated.
• The visual and instrumental colour of the beef steaks and ground beef
were similar to that of fresh meat.
• Pathogenic bacteria were not detected, and psychotropic bacterial
counts were lower than 7.5 log CFU/g.
(A. C. Venturini et al., 2014 )

19. The term CAP usually is applied to packaging of respiring
food products:
– Fresh meat
– Poultry
– Fish
or
– Foods with respiring biological contaminant such as
microorganisms
YHA_ITP

20. Figure: Effect of bacterial count in air and MAP environment Vs time period

21. MAP/CAP for red meat
O2 : 60% - 80%
CO2 : 20% - 40%

22. -continued
• The microbial spoilage is usually dependent on the pH in the meat; a
lower pH level provides for a longer shelf- life.
• Beef, for example, can therefore be vacuum packaged because of its
low muscle pH, whereas lamb, which has higher muscle pH, must be
packaged in a CO2 enriched atmosphere in order to achieve a
comparable shelf-life.
(Church and Parsons, 1995)

23. MAP/CAP for bread and related products
O2 < 1%
CO2 > 20%
Storage life
Bread: 4 weeks
Cookies :6 months

24. Other Application MAP/CAP
Pasta : CO2 20%
N2 70%
Pizza : CO2 50%
N2 50%
Sandwich : CO2 80%
N2 20%
Storage life : 4 weeks
Storage life : 3 weeks
Storage life : 3 weeks
(+refrigeration)

25. Poultry
 Poultry does not undergo irreversible discoloration of the meat surface
in the presence of O2.
 The spoilage of raw poultry is mainly caused by microbial growth,
particularly growth of pseudomonas species and achromobacter
species. These aerobic spoilage bacteria are effectively inhibited by the
use of CO2 in MAP. Levels of CO2 in excess of 20% are required to
extend the shelf-life of poultry significantly.
 Package collapse and excessive drip can be a problem for raw poultry.
 The achievable shelf-life of MA packed raw poultry and game bird
products will depend on the species, fat content, initial microbial load,
packaging type, gas mixture and temperature of storage.
(Stiles, 1991)

26. RTE FOODS
 For RTE foods the main spoilages are microbial growth, colour changes
and oxidative rancidity.
 Cooked, cured and processed meat products containing high levels of
unsaturated fat are liable to be spoiled by oxidative rancidity, but MAP
with CO2/N2 mixtures inhibits this undesirable reaction, and delays the
development of oxidative warmed-over flavour.
(Church and Parsons, 1995).

27. -continued
 Studied the influences of MAP on selected ready-to-eat foods. MAP
with >20% CO2 retarded the growth of mould and discoloration of ham
pizzas.
Ahvenainen et al. (1990)

28. Recommended conditions
Product Temperature (oC) O2 (%) CO2 (%) N2 (%)
Meat
Fish
Poultry
Pasta
Bread
Apple
Broccoli
Tomato
Banana
0 – 2
0 – 2
0 – 2
0 – 5
2 – 22
0 – 5
0 – 5
8 – 12
12 – 15
30
30
0
0
0
2 – 3
1 – 2
3 – 5
2 – 5
30
40
30
60
100
1 – 2
5 – 7
0
2 – 5
40
30
70
40
0
Rest
Rest
Rest
Rest

29. STORAGE CONDITION
Product Non-MAP MAP
Fresh red meat 2-3 days 6-21 days
Fresh poultry 3-10 days 12-18 days
Cooked poultry 5-14 days 21-30 days
Fresh pasta 3-5 days 45-60 days
Uncooked sausage 4-5 days 15-16 days

30. Shelf-life increase by possibly 50–400% Added costs
Reduced economic losses due to longer shelf-
life
Temperature control necessary
Decreased distribution costs, longer
distribution distances and fewer deliveries
required
Different gas formulations for each product
type
Provides a high quality product Product safety to be established
Easier separation of sliced products
Increased pack volume – adversely affects
transport costs and retail display space

31. CONCLUSION
 We believe that MAP/CAP, if used properly for the right commercial
reasons, offers sufficient benefits to both the food industry and to
consumers thereby suggesting that this is one of many alternatives.
 The industry should consider and use as part of a high quality food
product like fish, fruits and vegetabels.
 The use of MAP/CAP to make up for defects in food quality and/or
limitations in transportation will only lead to consumer unhappiness
and a black mark for the process.
 We strongly encourage the right people to use this technology for the
right reasons in the right way.