different types of MOs in map of fish

1. MAP – Gas packaging, vacuum packaging

3. Introduction
It is a form of packaging involving the removal of
air from package and either gases is filled in the
pack or without any gas, pack is sealed.

4. Introduction
 Types of MAP for fish products
1. Gas packaging
2. Vacuum packaging
Gas packaging:
In this type of MAP, the pack is filled with mixture of gases or single
gas.
Vacuum packaging:
In this type of MAP system in which air is evacuated from pack and
no gas mixture is filled .

5. MODIFIED ATMOSPHERE PACKAGING OF FISH: Gas packaging
The principle in MAP of fish product is to reduce or retard the
growth of selective spoilage organisms (SSO).

6. Factors affecting the shelf life of fish under MAP :
1. Initial Microbial load on the fish and fish product

7. Factors affecting the shelf life of fish under MAP :
2. The species of the fish – temperate water fish and
tropical water fish, Enzyme activity

8. Factors affecting the shelf life of fish under MAP :
3. Fat content of fish - Autolysis

9. Factors affecting the shelf life of fish under MAP :
4. The ratio of G/P

10. Factors affecting the shelf life of fish under MAP :
5. Temperature of storage

11. Non-microbial effects of MAP
• Carbon dioxide in the MAP may cause bleaching of the fishery
products specially the carotenoid containing fish like salmon.
• Texture and exudate losses may also be affected when using MAP.
Increasing the concentrations in MAP enhances exudation by
acidifying fish muscle, so that the water holding capacity of fish
proteins is reduced.
• The MAP gas composition may also influence the perceived odour
and flavour of the fisheries product. It is assumed that O2
concentrations higher than 50% also provide a fresh odour to the
packaged product
Effect on sensorial quality

12. Effect on oxidative rancidity
• O2 concentration in the MAP gas mixtures influenced the oxidation level
of MAP rainbow trout fillets (fatty fish species) during storage at 1±1 ◦C.
Significant differences were obtained in thiobarbituric acid (TBA) values
towards the end of shelf life, between vacuum packaged fillets and those
packaged with 10% O2.

13. Effect on MAP on fish spoilage
• Shewanella putrefaciens and Pseudomonas spp. are considered to be
the main SSOs for iced marine fish regardless of the origin of the fish
(Gram and Huss, 1996). The use of CO2 in MAP inhibits the growth of
Pseudomonas spp. and Shewanella spp.
• The use of CO2 favours the growth of gram-positive bacteria (e.g. LAB,
Brochothrix thermosphacta) or the CO2 resistant P. phosphoreum
• Although the presence of oxygen in the MAP gas mixture reduced the
growth rate of P. phosphoreum, it is still the dominant spoilage
microflora of cod fillets stored in oxygen containing modified
atmospheres
Effect of MAP on the spoilage microbiota of marine fish:

14. • MAP also favours the development of LAB in fresh fish. Numerous
studies on MAP of fatty and lean fish species have shown that total LAB
counts were relevant in fresh MAP fish
Effect of MAP on the spoilage microbiota of fresh water fish
• High level of CO2 inhibits the growth of aerobic microorganism. Carbon
dioxide and vacuum packaging of fish caught in freshwater results in
gram-positive bacteria, mainly LAB, dominating the microflora
Effect MAP on the spoilage mechanism
• As TMAO reductase is pH sensitive, using CO2 inside the package
indirectly inhibits TMA production. Packaging for marine fish that
contains a low concentration of or no oxygen, enhances this
metabolism

15. • hydrogen sulphide is a spoilage characteristic for aerobic chilled fish but
is not detected in CO2 packaged spoiled cod
• Ammonia production is also found to be lower in MAP fish products
compared with aerobically stored fish products
• High CO2 concentrations in MAP appear to have a repressing effect on
biogenic amine production. Santos (1996) reported that histidine
decarboxylase activity is inhibited in atmospheres of 80%CO2.
Effect of MAP on the microbial safety of fish products (Risks)
Listeria monocytogenes
• Cause illness if digested active cells.
• L. monocytogenes must not be allowed to exceed the limit of 2 log cfu/g
or to reach infectious doses in unspoiled products.

16. • Found in lightly preserved fish.
• Vacuum packaging or MAP with enhanced CO2 concentrations will delay
the growth of L. monocytogenes but is not enough to control the
growth of this pathogen completely.
• Can be killed by heat treatment before packaging
Clostridium botulinum
• The single most important concern for MAP.
• Potential for the outgrowth and toxins production
• Non-proteolytic, psychrotrophic (grow at a low as 3.3 °C)
• Grows and produces toxin without the sign of spoilage

17. • If the package is contaminated with this microorganism initial stages of
processing, with in the 10-12 days the product will be toxic
Recommendation for controlling the growth of Clostridium botulinum
(Betts. 1995)
• A heat treatment of 90°C for 10 min or equivalent (thermal processing)
• A pH value of 5 or less
• A minimum salt level of 3.5% NaCl in the aqueous phase
• A water activity or less throughout all parts of food
• A combination of heat and preservative factor or components – Nitrite

18. Application of MAP on fish and fisher products
Type of fish CO2% O2% N2%
White non-processed fish/non-
fatty fish
40 30 30
Smoked fish 40 60
Fatty fish 40 60
 Because of the risks already discussed, it would appear reasonable to
aim for a target shelf life of 10–14 days at 3◦C.

19. Packaging material used for MAP
For trays – PVC, APET/PE, HDPE, EPS/EVOH/PE
For lidding – PET/PE-EVOH-PE
For bulk packaging – PA/PE and PA/EVOH/PE
Vacuum Packaging:
• Used for delicate products such as smoked or pickled fish, shucked
scallops, and soft shells crabs
• Films with low oxygen permeability are used
• VP has high shelf-life of product compare to gas packaging, when stored
at 3°C

20. • Success factor for VP-
• Initial quality of fish – before packaging the microbial load and damage
of fish should be very less. The fish should be of very high quality.
• Temperature control throughout the storage period.

21. Potential problem of MAP and VP of Fish
Pack collapse
• Pack collapse occurs
• CO2 permeates through packing films up to 30 times faster than N2
• CO2 is fat and water soluble
• Solubility increases when temperature decreases
To minimise pack collapse
• Reducing CO2 content
• Increasing the product to gas ratio
• Injecting gas with a slight overpressure
• Pre-treating product with CO2 saturated water or bicarbonate solutions

22. Increased exudates/drip loss
• Fish loses about 1-3% drip during normal storage
• Drip levels up to 14% have been found for prawns
• Decrease in water holding capacity of proteins due to a decrease in pH
Discolouration
• The precipitations of sarcoplasmic proteins at low pH
• Fading and browning have been attributed to packing in 100% CO2
TMA production
• TMA is produced only in fish in which contain adequate amounts of
TAMO
• TMA production has been shown to be inhibited by MAP
• Released when the consumer opens the pack

23. Histamine production
• Produced by microbial decarboxylation of histidine
• Numerous different bacterial species to possess histadine
decarboxylation activity
• Vibrio, Proteus, Morgnella morganii, Klebsiella pneumoniae, Hafnia
alvei, etc.
• FDA legal limit of Histamine is 5mg/100 fish (1996)

24. Advantages of MAP
• Increased shelf life of products
• High quality products and reduced economic loss
• Products can be distributed longer distances, resulting in a decreasing in
distributing cost
• Clear view of products
• Hygienic stackable pack, sealed and free from product drip

25. Disadvantages of MAP
• High Temperature sensitivity
• Specialized training and equipment required
• Different gas formulation required for each product
• Potential growth of food-borne pathogens C. botulinum
• Benefits of MAP are lost once the pack is opened