Modified atmospheric packaging (MAP) and controlled atmospheric packaging (CAP) extend the shelf life of foods by modifying the gas composition around foods. Nitrogen gas is commonly used in MAP and CAP as an inert filler to reduce oxygen levels and prevent oxidative reactions. For perishable foods, low oxygen levels achieved through nitrogen addition reduce the respiration rate and slow quality deterioration. Nitrogen is also used to displace air during packaging of dry foods like grains and cereals to create an environment lethal to insects and microbes.

1. CONTROLLED AND MODIFIED
ATMOSPHERIC PACKAGING
• Effect of Nitrogen on storage of durable and
perishable commodities
By-
Debomitra Dey
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2. INTRODUCTION
• CAS/CAP has been used for bulk storage and
transportation of fresh fruits and meat, has been
in action for over 100 years.
• By 1970’s polymeric packages have been
available where the gases in the atmosphere can
be controlled or modified based on the need.
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3. • CAP- A controlled atmosphere is an agricultural storage
method. An atmosphere in which oxygen, carbon dioxide and
nitrogen concentrations as well as temperature and humidity
are regulated.
• MAP- Modified atmosphere is the practice of modifying the
composition of the internal atmosphere of a package; in order
to improve the shelf life.
• Gases are combined in three ways for use in modified
atmospheres: inert blanketing using Nitrogen Gas , semi-
reactive blanketing using CO2 / N2 or O2 /CO2 /N2 or fully
reactive blanketing using CO2 or CO2 /O2 (Parry 1993;
Moleyar and Narasimham 1994).
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4. MAP (Modified Atmospheric Packaging)
• Enclosure of food in package.
• Atmosphere is modified or altered .
• Increasing shelf life and maintenance of quality
of product.
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5. MAP (Modified atmosphere packaging)
• Prolonging shelf life of product.
• Air composition in the package in changed.
• By alteration of composition the initial freshness can be
maintained
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6. Modified atmosphere
• Active or Passive
• Active modification- by gas flushing.
• Displacement of air with controlled or desired gases.
• Passive modification- associated with the
consequence of the metabolism of food, viz. respiration,
microbial metabolism
• Polymeric film, may also contribute to this attribute due
to gas permeation.
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7. MAP
• It has been associated with chilling of food
products. (exception baked foods)
• Chilling is greatly enhanced when employed in
combination with modification of gas
atmosphere.
• As deteriorative actions include aerobic
respiration due to reduced O2 levels.
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8. Vacuum Packaging
• Respiring foods, like flesh foods.
• Form of MAP.
• After initial modification, i.e., removal of air,
biological action continues.
• For ex. Level of CO2 increases as it produced by
respiration of fruits and vegetables or by
microorganism.
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9. Controlled Atmospheric Packaging (CAP)
• Enclosure of food.
• Impermeable package- gaseous environment.
• Gases- N2, O2, CO2, water vapour.
• Controlled environment for increasing shelf life.
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10. More about MAP & CAP
• Alteration of concentration of atmospheric gases in
storage prevents-
▫ Mould growth
▫ Insecticidal attack
▫ Quality deterioration
Alteration- low O2 by adding N2 gas mixture resulting
from burning HC or high CO2 environment.
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11. Advantages
• Extend the period of storage.
• As no chemicals are used, costs are significantly lower.
• Environmental friendly packaging.
• Dry conditions are unfavourable for growth of insects;
hence, proves to be effective for insecticidal effect.
• Additionally 3.2% O2 or 4.3% CO2 is required for
complete mortality.
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12. Advantages and Disadvantages of MAP
Advantages Disadvantages
• Increase in shelf life: 40-500%.
• Reduced economic losses due to
longer shelf life.
• Provides a high quality product.
• No (some) chemical preservative is
added.
• Odourless and convenient packages.
• Sealed packages (Barrier against
recontamination)
• Cost rises due to addition of
gases, packaging materials and
machinery.
• Temperature control necessary.
• Gas formulation differs
depending upon the product.
• Loss of benefit once packs are
opened or if leaks found.
• CO2 dissolving may lead to pack
collapse and increased drip.
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Handling, Packaging and
Storage
Source- Minimal Processing technologies in Food Industry, CRC Press. 2002

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STORAGE OF GRAINS
• Storage is integral part while stages of transportation of grains
from farm to processor to consumer.
• Due to inadequate infrastructure the grains are susceptible to
infection by pests and insects.
• Traditional methods at times fail to offer a longer storage period.
• Hence, modern storage methods of packaging are used to
prolong shelf life of grains.

14. Hydrobaric Storage
• Placing food in environment: pressure, air
temperature, humidity controlled.
• Change in rate of air is closely regulated.
• Only O2 is required, as O2 concentration is directly
proportional to pressure.
• Research is been carried out for its effect on flesh
foods and other perishables.
• Not employed commercially.
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15. Gases used in MAP
NITROGEN: Nitrogen is an inert gas and is used to exclude air and, in
particular, oxygen. Used as a balance gas (filler gas) to make up the
difference in a gas mixture, to prevent the collapse of packs containing
high-moisture and fat-containing foods, caused by the tendency of these
foods to absorb carbon dioxide from the atmosphere. For modified
atmosphere packaging of dried snack products 100% nitrogen is used to
prevent oxidative rancidity.
• CO2
• O2
• Argon
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16. Nitrogen gas in packaging
• Inert, Tasteless
 Less prone to pass into product or out of product
▫ Used as filler , cushion, replacing O2
▫ as alternative to vacuum packaging
▫ product is fragile
▫ To limit collapse caused by CO2 absorption
◦ Doesn’t possess bacteriostatic activity
◦ Not very soluble in water, used for displacing Oxygen
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17. MAP of Durable products
• Grains are dry, cannot support growth of bacteria (Jay, 1992)
• Insects and moulds cause major spoilage of grains.
• Anoxic environment lethal effect on insects and pests.
• MAP alternative to use of chemical fumigants and insecticides, as
they have carcinogenic effects.
• Insects and Moulds develop resistance against insecticides and
chemical fumigants.
• Resistance to MAP may seldom occur, as it is dependent upon
several biotic and abiotic factors.
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18. Modified Atmosphere Packaging for grains
• Factors for control of insects in stored commodities:
(Storey, 1979)
▫ Large area available to displace existing atmosphere in
large bulk.
 Atmosphere lethal to storage pests within reasonable time.
 Should have no harmful effect on quality of treated
commodity.
▫ Storage system should have adequate gas holding
capacity.
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19. Effect of Nitrogen on storage of grains
• Studies conducted by Shejbal in 1980, trials with
cereal grains with N2 is advantageous at all
temperature and moisture content up to 30°C and
19% compared to storage in air.
• Oilseeds storage life is prolonged when stored with
environment with higher N2 than air.
• Disadvantage associated with N2 fumigation &
storage technique related to storage facility.
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20. Application of N2
• Shredded lettuce gas flushed- 5% O2 , 5% CO2,
90% N2, vv) – prevent browning prior to atm
equilibration (Ballantyne et a1 (1988b)).
• Beverages- drop of N2 is added, into beer and
carbonated drinks before seaming
▫ N2 used as filler, flushing out O2, this helps increasing
shelf life, retains aroma and reduces can corrosion.
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Herbert et al, 2013 Growth of spoilage microflora under N2
concentration

22. Effect of N2 (perishable product)
• Normally, the concentration of O2 in a pack is kept
very low (1-5%) by use of Nitrogen Gas Generators
to reduce the respiration rate of fruits and vegetables
(Lee and others 1995).
• Reducing the rate of respiration by limiting O2
prolongs the shelf life of fruits and vegetables by
delaying the oxidative breakdown of the complex
substrates which make up the product.
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23. MAP in Minimally processed products
• Packaging allows manufacturer to impose a barrier
between food and external environment.
• Immediate environment can be altered, sums up
MAP.
• Few chemical preservative maybe added for
minimally processed product.
• CO2 is highly soluble in water, tends to be absorbed
by moist food.
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24. MAP in Minimally processed products
• For packaging of moist foods, N2 may be added.
• On the other hand, disadvantage associated with
N2:
 No bacterostatic effect
 Dangerous alternative, if food susceptible to
bacterial growth
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N2 gas used for processing of Blueberries

26. N2 in Packaged cereal products
• Dry product.
• Ready to eat cereals – excludes light and O2.
• CO2 along with N2 can be used to prevent Lipid
Oxidative, that causes rancidity in products.
• Ready to eat cereal products have high ratio of
unsaturated to saturated fats.
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27. N2 in packaging of Fresh Pasta products
• Falls in category of REPFED.
• Gas comp for storage of Pasta- 100% N2 or 70-80%
Co2 and 20-30% N2.
• Survey study for Staphylococci spp in wet pasta
product under (20:80) mixture from five different
processor showed that 12% of fresh products were
contaminated with S.aureus.
• The result indicated that proper refrigertaion was
essential to ensure safety of MAP wet pasta.
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28. References
• Sahay K.M., Singh K.K., Unit Operations of Agricultural Processing.
• Robertson G., Food Packaging- Practices and Principles.
• Food Packaging Technology Handbook.
• Church I J, Parsons A L, 1995 Modified Atmosphere Packaging
Technology : A Review, J Sci Food Agric 1995,67,143-152
• Vicente M. Gomez-Lopez, Decontamination of Fresh and
Minimally Processed Produce
• C.M.D. Man, Adrian A. Jones, Shelf Life Evaluation of Foods
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