The document discusses modified atmosphere packaging (MAP) for fresh produce. MAP involves modifying the atmosphere surrounding food products to extend shelf life and maintain quality. It summarizes the key principles and benefits of MAP, including using gases like CO2, O2, and N2 to delay spoilage. Methods of MAP discussed include passive and active modification to control the gas levels. Equipment for MAP aims to flush out air and replace it with a controlled gas mixture. The selection of packaging materials depends on factors like gas and moisture permeability.

2. University of Horticultural
Sciences, Bagalkot
College of Horticulture, Bengaluru
Novel MAP gases and Novel MAP
applications for fresh-prepared produce
Ms.Ayeeshya H. Kolhar
I - Ph. D. (Hort.)
UHS17PGD223

3. There is continuous improvement in methods of transporting food from producers to
consumers by retaining the quality vai cold chain maintenance during storage and
transit.
Cold chain maintenance coupled with modification of the atmospheric gases was the
basic principle used in the CAS for fresh produce and meat products.
Since from 1970s there is widespread availability of polymeric packages, this
approach has been applied to consumer packs and given the name modified atmosphere
packaging (MAP) because the atmosphere surrounding the food is modified but not
controlled.
MAP can be defined as the enclosure of food in a package in which the atmosphere
inside the package is modified or altered to provide an optimum atmosphere for
increasing shelf life and maintaining food quality
Introduction

4. Shelf life increase from 50% to 400%
Reduced economic losses due to longer shelf life
Decreased distribution costs, longer distribution distances and fewer deliveries required
Provides a high quality product
Easier separation of sliced products
Centralized packaging and portion control
Improved presentation—clear view of product and all-around visibility
Little or no need for chemical preservatives
Sealed packages are barriers against product recontamination and drip from package
Odorless and convenient packages
Advantages of MAP

5. PRINCIPLES
MAP delays the deterioration of foods that are not sterile and whose enzymic systems may
still be operative.
“Storage of the packed produce in chilling temperature coupled with modification in the
gaseous composition in the surrounding atmosphere (particularly O2 and CO2) is known to
reduce the undesirable biochemical and physiological changes thus maintaining the produce
quality”
Storage of the produce in chilling temperature has the following effects
1. Growth of microorganisms
2. Postharvest metabolic activities of intact plant tissues, and post slaughter metabolic
activities of animal tissues
3. Deteriorative chemical reactions, including enzyme-catalyzed oxidative browning,
oxidation of lipids, chemical changes associated with color degradation, autolysis of fish and
loss of nutritive value of foods in general
4. Moisture loss

6. The normal composition of air by volume is 78.08% N2, 20.95% O2, 0.03% CO2,
0.93% argon (Ar) and traces of other nobel gases in very low concentrations.
The main gases used in MAP are O2, CO2 and N2, either singly or in combination.
Gases also have significant solubility in the lipid phase of foods. For example, at 0°C
and atmospheric pressure, 1 L of vegetable oil can absorb approximately 6 mL of N2, 12
mL of O2 and 1 L of CO2.
GASES USED IN MAP

7. Table1. Solubilities of Gases in Water at Atmospheric Pressure and
various Temperatures
Temperature
(°C)
O2 N2 CO2 Ar CO
0 69 29 3350 100 44
5 62 27 2770 89 40
10 58 24 2320 78 36
20 42 18 1690 59 28
Note: Solubilities given for carbon dioxide include all chemical species of the
gas and its reaction products with water.

8. CARBON DIOXIDE
CO2 is the most important gas in the MAP of foods, due to its bacteriostatic and
fungistatic properties.
Acidic pH found in food products result in dissolving the CO2 lead to formation of
hydrates of carbonic acid H2CO3 this is known to disrupt microbial cell membranes and
inhibit respiratory enzymes.
CO2 + H2O↔H2CO3
It then ionizes to release bicarbonate and an H+ ion that can lower pH depending on the
buffering capacity of the food.
H2CO3 ↔HCO3 + H+
When the pH of a CO2 solution rises to 8.0 (most unlikely in foods), the HCO3
− may
even dissociate further to form CO3
2−
HCO3 ↔ CO3
2 ¯ + H+

9. OXYGEN
O2 promotes several types of deteriorative reactions in foods including fat
oxidation, browning reactions and pigment oxidation.
Most of the common spoilage bacteria and fungi require O2 for growth.
The O2 is either excluded or reduced to as low a concentration as possible.
However O2 is needed for the respiration of fruits and vegetables or the
retention of color in red meat.

10. Fig.1 Hypothesised inhibition of microbial growth by high O2 MAP

11. Hypothesised inhibition of enzymic discoloration by high O2 MAP.

12. NITROGEN
It has a lower density than air and a low solubility in water and other food constituents,
making it a useful filler gas in MAP to counteract package collapse caused by CO2
dissolving in the food.
It influences the microorganisms in perishable foods by retarding the growth of aerobic
spoilage microbes but it does not prevent the growth of anaerobic bacteria.
CARBON MONOXIDE
It is highly reactive and very flammable. It has a low solubility in water but is relatively
soluble in some organic solvents.
Lipid oxidation and browning are reduced and the shelf life of the food is prolonged.
CO at 5%–10% (combined with less than 5% O2) is an effective fungistat, which can be
used on commodities that do not tolerate high CO2 levels.
However it’s commercial application has been limited because of its toxicity, its explosive
nature at 12.5%–74.2% in air and the fact that it has a limited effect on microorganisms.

13. NOBLE GASES
They lack of reactivity, include helium (he), argon (ar), xenon (xe) and neon (ne).
Ar is considered to be completely inert, known to have competitive inhibitor of
respiratory enzymes, including oxidases.
It also slows down the rate of production of volatile amino bases in seafood, inhibits
enzymic discoloration, delays the onset of textural softening, extends the microbial lag
phase, inhibits microbial oxidases and enhances the effectiveness of CO2 by
weakening microbes, thereby enabling the use of less CO2 in MAP.
Ar can reduce the respiration rates of fresh produce and hence have a direct effect on
extension of shelf-life

14. GAS MIXTURES
The gas mixtures used for MAP of different foods depend on the nature of the food and
the likely spoilage mechanisms.
Spoilage is mainly microbial, the CO2 levels in the gas mix should be as high as
possible, limited only by the negative effects of CO2 (ex., Package collapse) on the
specific food.
Gas compositions for this situation are 30%–60% CO2 and 40%–70% N2.
O2-sensitive products where spoilage is mainly by oxidative rancidity, 100% N2 or
N2/CO2 mixtures (if microbial spoilage is also important) are used.
For respiring products, it is important to avoid too high a CO2 level or too low an O2
level, so that anaerobic respiration is prevented.

15. METHODS OF CREATING MA CONDITIONS
It is also known as commodity-generated MA charecterised by atmosphere high
in CO2 and low in O2 passively evolves within a sealed package over time as a
result of the respiration of the product.
Ideally, the gas permeabilities of the packaging film are such that sufficient O2
can enter the package to avoid anaerobic respiration, while at the same time excess
CO2 can diffuse from the package to avoid injuriously high levels.
Passive modification is commonly used for MAP of fresh respiring fruits and
vegetables.
PASSIVE MA

16. ACTIVE MA
Active modification involves displacing the air with a controlled, desired mixture of gases,
a procedure generally referred to as gas flushing
Involves use of CO2 O2 and C2H4 Scavengers and moisture absorbers etc.
Vacuum packaging of the food products

17. EQUIPMENT FOR MAP
Equipment for MAP must generally be capable of removing air from the package and
replacing it with a mixture of gases
Basically three types of packaging equipment used for MAP:
1. Horizontal or vertical form-fill-seal (FFS) machines using pouches or trays
2. Snorkel machines using preformed bags or pouches
3. Chamber machines using preformed pouches or trays

18. FORM-FILL-SEAL MACHINES
FFS machines form pouches (vertically or horizontally), or thermoformed trays
with a heat sealed lid, from rollstock.
The desired gas mixture can be introduced into the package in pouches in a
continuous countercurrent flow to force out the air, after which the ends of the
web are heat sealed and the packages cut from one another.
In the tray version, product is placed in the tray and a vacuum drawn, after
which the desired gas mixture is introduced and the top web of film heat sealed to
the base tray.

19. CHAMBER MACHINES
The filled package (either a preformed pouch or tray inside a bag) is loaded into a
chamber, a vacuum is pulled and the package is then flushed with the gas mixture and
heat sealed.
This is a batch process, is relatively slow and most suitable for bulk or master packs.
SNORKEL(PROBES) MACHINES
Snorkel machines operate without a chamber. The product is placed inside a large flexible
pouch (or bag) and positioned in the machine.
Snorkels or probes are inserted into the pouch and remove air, after which the vacuum is
broken by the addition of the desired gas mix.
The probes are then removed and the package is heat sealed. These machines are used
mainly for bulk packaging and for so-called master packs in which individual retail packs are
packaged in a large MA pouch or bag.
Chamber machine

20. PACKAGING MATERIAL FOR MAP
The characteristics to be considered when selecting packaging materials for MAP
permeability of the package to gases and water vapor, mechanical properties, heat
sealability and transparency.
For non respiring products, all the common high gas barrier structures have been used in
MAP, including laminates and coextruded films containing PVdC, EVOH and PAs as a
barrier layer. The inside layer is usually LDPE to provide a good heat seal and moisture
vapor barrier.
For the MAP of respiring produce such as fruits and vegetables, the choice of suitable
packaging materials is much more complex, and no easy solutions are available due to the
dynamic nature of the food.

21. Ideally, the packaging material should maintain a low O2 concentration (3%–5%) in the
headspace and prevent CO2 levels exceeding 10%–20%. Polyolefin films are normally
used, but to achieve the desired MAP, it has been necessary to perforate the film or (more
recently) use a special batch; O2 and CO2 absorbers have also been used on a limited scale.
To prevent condensation of water vapor on the inside of the package due to temperature
difference between the package contents and the packaging material, antifogging agents
are used.
These amphiphilic additives function by decreasing the interfacial tension between the
polymer and the condensed moisture vapor, enabling the water droplets to coalesce and
spread as a thin transparent layer across the surface of the film. Typical antifogging agents
include nonionic ethoxylates or hydrophilic fatty acid esters

22. APPLICATIONS OF MAP
MAP is being successfully used by many food processing companies around the world to
extend the shelf life and retain the quality of a wide variety of foods.
The use of hurdle technology involving MAP in combination with deliberate
manipulation of aw, pH and/or redox potential, as well as the use of preservatives,
bacteriocins, ultra high pressure and edible coatings, could lead to better control of potential
pathogens and thus a safer product.
Several novel technologies offer the potential of further improvements in the shelf life
and safety of MAP foods. These include the use of active and intelligent packaging in
which O2 and C2H4 absorbers and CO2 emitters, used either alone or in combination with
MAs, are likely to find wider application as more cost-effective and innovative designs are
commercialized.

23. COMMERCIAL APPLICATIONS OF MAP IN
FOOD PRODUCTS

24. FRUIT AND VEGETABLES
Modified atmospheres packaging prolongs the shelf life of fresh fruit and vegetables.
As the are living in nature special requirements need to be met with regard to nature of
the packaging and atmosphere. By taking the product‘s breathing and the permeability of
the film, typically via micro-perforation, into account, the composition of carbon dioxide,
nitrogen and low amounts of oxygen ideal for the product can be maintained. The term used
here is an EMA (equilibrium modified atmosphere).
The gas composition is individually adapted to the corresponding product. Thorough
cleaning along with hygienic processing are the fundamental preconditions for long-lasting
freshness.
Modified atmospheres, in conjunction with corresponding cooling, can be used to extend
the shelf life of fresh produce, while achieving an attractive packaging design at the point
of sale.

25. Recent MAP applications in fruits

26. Recent MAP applications in vegetables and mushrooms

27. PASTA AND READY-MADE MEALS
The nature and composition of fresh pasta and, in particular, readymade meals
are very different. Above all, multi-component products such as ready-made
pizzas or sandwiches contain many different foods with differing shelf lives and
spoilage properties.
In the majority of cases, modified atmospheres can significantly extend the
shelf life without using oxygen. Mixtures of CO2 and nitrogen are used here. The
concentration of the gases is oriented to the content of the product. If, for example,
there is a risk that large volumes of CO2 will be absorbed by the product, the
nitrogen content should be chosen higher to prevent the packaging from
collapsing.

28. SNACKS AND NUTS
Snack products, for example potato crisps or peanuts, primarily involve problems
associated with the fat content of the food. There is a risk of oxidation, whereby the
products can quickly become rancid if the packaging is not optimal. To extend the shelf
life, it is therefore important to minimise the contact with oxygen.
Modified atmospheres with 100 % nitrogen are frequently used. In this way, a
premature spoilage can be prevented, while these atmospheres also provide protection
from mechanical damage to sensitive products, e. g. potato crisps in conventional
packets.

29. WINE
Gases or gas mixtures are often used to protect wine in the different phases of its
production process and to retain the quality of the product.
They are mainly used to avoid contact with oxygen and prevent microbial
deterioration. The tank headspace is replaced with an inert gas or a gas mixture,
for example of CO2, N2 or Ar. The composition of the gases is chosen according to
the type of wine.

30. As a dried product, coffee is relatively insensitive to spoilage by
microorganisms. However, the risk of the fatty acids it contains oxidising and
making the product rancid is greater.
To prevent this, coffee is packaged with the exclusion of oxygen. Instead, a
modified atmosphere comprising pure nitrogen is frequently used in coffee
sachets or capsules.
COFFEE

31. MEAT AND SAUSAGE PRODUCTS
Meat and sausage products, above all raw meat, are very prone to spoilage
No matter whether beef, pork or poultry – spoilage begins from the moment
of slaughter and especially all butchering. Besides high hygiene standards
and permanent cooling, modified atmospheres can significantly extend the
shelf life of meat and sausage products.
 CO2 is the most important among the protective gases. At concentrations
above 20 %, CO2 can considerably reduce microbial growth.
In the case of red meat, there is also the risk of oxidation of the red colour
pigments. The meat will lose its red colour, becoming grey and unappetising
in appearance. This oxidation is especially prominent with beef.
A high oxygen content in protective gas packaging can prevent oxidation. A
low carbon monoxide content (approx. 0,5 %) can also help to retain the red
colour of meat. However, the use of gas is not allowed in the EU.

32. Table Recent MAP applications in meat products

33. DAIRY PRODUCTS
Vacuum packaging was frequently used in the dairy products
CO2 effectively prevents mould formation but not in excess which affect the
maturation of the cheese.
Soft cheese can quickly become rancid which can be overcome by enriching
with CO2 modified atmospheres.
However, as soft cheese absorbs CO2 to a significantly higher extent, there is a
risk of the packaging collapsing. A correspondingly lower CO2 content should
therefore be chosen.
In the case of milk products such as yoghurt or cream, there is a risk of the
products absorbing too much CO2 and becoming sour. A lower CO2 content
should therefore be chosen.
Milk powder, above all for use in baby food, is a highly sensitive product. It is
especially important to ensure that oxygen is displaced from the packaging in
order to extend the shelf life.

34. BREAD AND CAKE
With bread, cake and biscuits, the shelf life is primarily affected by
potential mould formation. A high standard of hygiene during production and
packaging can significantly minimise this risk.
Packaging involving a modified atmosphere with CO2 and without oxygen
extensively prevents the products from becoming mouldy and extends the
shelf life.
To prevent the packaging from collapsing owing to CO2 absorption by the
products, nitrogen is used as a supporting gas in many cases.

35. Objective: Study the effect of modified atmosphere packaging at low temperature
storage (0°C) on the quality characteristics (weight loss, color, hardness, organoleptic
attributes, off odours) of ready-to-eat shredded cabbage.

36. White cabbage Cv. Bunner
About 100±2 g shredded cabbage was placed in heat sealed bags (180 mm x
200 mm) which had a surface area of 720 cm2, made with 30 μm thick MDPE
packages (O2 permeability 6.170±730 mL m-2 d-1 bar-1 and CO2 permeability
41.520±1830 mL m-2 d-1 bar
1. SA (MDPE packaging film, injection of a mixture with 5% Ο2, 10% CΟ2
balanced with N2),
2. SB (ΜDPE packaging film with one macro-perforation 3 mm in diameter)
3. Control (polystyrene trays wrapped with PVC).

37. Fig. 2 Effect of SA and SB packaging on ethylene concentration in shredded
cabbage during storage at 0°C
Manolopoulou Ε. and Varzakas T. H. (2013)

38. Fig.3 Effect of SA and SB packaging on the quality characteristics (discoloration,
pepper spot and overall visual quality) of shredded cabbage.
Manolopoulou Ε. and Varzakas T. H. (2013)

39. Modified atmosphere in SA packaging, low in Ο2 (1.5%) and high in CΟ2 (17%)
retained the texture, reduced browning of the cut surfaces, retained total visual
quality and sensory evaluation, and increased shelf life of shredded cabbage to 23
days.
Conclusion

40. Objective: To study the effect of elevated CO2 and low and high O2 levels on the
microbial quality with special attention on growth of Listeria innocua.

41. Table 2. Respiration rate and respiratory quotient (RQ) of fresh-cut butter
lettuce

42. Fig. 5. Changes in the
population of Listeria
innocua (A), aerobic
mesophilic bacteria (B),
lactic acid bacteria (C),
and yeasts (D) on fresh-
cut butter lettuce
75 kPa O2+15 kPa CO275 kPaO2+0 kPa CO2 5 kPaO2+15 kPa CO2
5 kPaO2+0 kPa CO221 kPa O2+0 kPa CO2

43. Super atmospheric O2 condition in combination with 15 kPa CO2 retarded growth of
aerobic mesophilic bacteria allowing an extension of shelf-life until 7 days at 7 °C
according to recommended limit criteria (total aerobic counts lower than 7.7 log cfu g–1).
Conclusion

44. Thank u….