Week: 12 Modified atmosphere packaging (MAP) and vacuum packaging (VP) to seafood safety

1. Week: 12 Modified atmosphere packaging (MAP) and vacuum packaging (VP) to seafood safety

2. Definitions and Terminology Modified Atmosphere Packaging (MAP) “ It is a form of packaging involving the removal of air from the pack and the replacement with single gas or mixture of gases” (Parry, 1993). Vacuum Packaging (VP) VP is also a type of MAP system because air is evacuated from a pack and not replacedand then the package sealed

3. Modified atmosphere packaging components for seafood Fish Gas mixtures Gas/fish ratios Packaging materials

4. Modified atmosphere packaging components for seafood • Fish • biological structure • chemical composition • extremely perishable and generally spoil • faster • Gas mixtures • carbon dioxide (CO2), oxygen (O2) and nitrogen (N2) • for white fish and shellfish40/30/30:CO2/N2/O2 • for fatty and smoked fish60/40: CO2/N2

5. Modified atmosphere packaging components for seafood • Gas/fish ratios • gas/products ratio 2:1 to 5:1 for MA packed fish while the CO2 • concentration 20% and 100% • recommended product ratio 3:1 with a minimum concentration of • 20% CO2 • Packaging materials • good visual display, low water vapour transmission, high gas barrier • mechanical strength to withstand machine handling and • subsequent storage • polyvinyl chloride (PVC), polyethylene terephthalate (PET), • polypropylene (PP) and polyethylene (PE) • tray with an impermeable film

6. Gases used in modified atmosphere packaging • Oxygen (O2) • stimulates the growth of aerobic bacteria and inhibits the growth • of the strictly anaerobic bacteria • presence of oxygen can cause oxidative rancidity in fatty fish • low levels might induce browning reactions • low level oxygen inhibit the growth of pathogenic anaerobic bacteria • such as C. botulinum, Clostridium perfringens • Carbon dioxide (CO2) • not inert and can bring about chemical changes in the microbial • cell and its environment • highly soluble in both water and lipids • 25% CO2 is recommended to control bacterial and mould growth • most effective in reducing the growth of aerobic and • Gram-negative psychrotrophic bacteria • negative effects of CO2 on the colour of fish, the texture of fish • and drip loss • high concentrations of CO2 cause excessive drip, metallic and sour • off-odors and off-flavors

7. Gases used in modified atmosphere packaging • Nitrogen (N2) • an inert and tasteless gas with a low solubility in both water and lipid • delaying oxidative rancidity and inhibiting the growth of aerobic • microorganisms • filler gas to prevent pack collapse due to its low solubility • Carbon monoxide (CO) • highly toxic gas and is not approved by the regulatory authorities • heath hazard for packaging machine operatives as well • The other gases • Potential gases: chlorine, ethylene oxide, nitrogen dioxide, ozone • and sulphur dioxide • unlikely to meet regulatory authorities approval due to safety concerns • Noble gases: xenon, argon and helium • permitted as food grade gases by EC legislation

8. Effect of oxygen on seafood Oxygen (O2) Development of aerobic microorganism Oxidation Darkening Discoloration Loss of aroma Appearance of mould Unpleasant flavor Bacterial degradation Reduced nutritional value Reduced freshness Loss of organoleptic qualities Products becomes unfit for consumption with passage of time

9. Oxygen requirement of some common food microorganisms (Parry,1993)

10. Effects of MAP on some common microorganisms

11. Effects of MAP on Clostridium botulinum Clostridium botulinum • the single most important concern for MAP • potential for the outgrowth and toxin production • non-proteolytic, psychrotrophic (grow at a low as 3.3oC) • grow and produce toxin without producing over sign of spoilage • Recommendation for controlling the growth of Clostridium botulinum (Betts, 1995) • a heat treatment of 90oC for 10 min or equivalent • a pH value of 5 or less • a minimum salt level of 3.5% NaCl in the aqueous phase • an water activity of 0.97 or less throughout all parts of food • a combination of heat and preservative factor or components • Potassium sorbate, sodium chloride, nisin and irradiation in combination with MAP are shown to be effective

12. Bacteriological changes Figure 1 Total viable counts (cfu/ml) in sardine stored in air, in VP and in MAP at 4oC. (Ozogul et al, 2004)

13. Potential problems of MAP and VP • Pack collapse • Pack collapse occurs • CO2 permeates through packing films up to 30 times faster than N2 • 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 products with CO2 saturated water or bicarbonate • solutions • pack in air • 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

14. Potential problems of MAP and VP • Discoloration • the precipitation 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 • TMAO • TMA production has been shown to be inhibited by MAP • released when the consumer opens the pack • Histamine production • produced by microbial decarboxylation of histidine • numerous different bacterial species to possess histidine • decarboxylase activity • Vibrio,Proteus, Morganella morganii, Klebsiella pneumoniae, • Hafnia alvei, etc. • FDA legal limit: 5mg/100g fish (1996) • EEC limit for histamine:10mg/100g fish (1991)

15. TMA production Figure 4 TMA content of herring stored in ice, in VP and in MAP at 4oC Figure 5 TMA content of sardines stored in air, in VP and in MAP at 4oC (Ozogul et al, 2002) (Ozogul et al, 2004)

16. Histamine production Figure 2 Histamine content of herring stored in ice, in VP and in MAP at 4oC Figure 3 Histamine content of sardines stored in air, in VP and in MAP at 4oC (Ozogul et al, 2002) (Ozogul et al, 2004)

17. ATP and breakdown products Concentration of ATP and related compounds (mmoles/g) Storage time (days) Storage time (days) (Ozogul et al, 2004)

18. Advantages and disadvantages of MAP • Advantages of MAP • Increased shelf life of products • High quality products and reduced economic loss • Products can be distributed longer distances, resulting in a decrease in • distribution cost • Clear view of products • Hygienic stackable pack, sealed and free from product drip • Disadvantages of MAP • Visible added cost, for example; cost of gases and packing materials • Temperature control required • Specialized training and equipment are necessary • Different gas formulation required for each product type • Potential growth of food-borne pathogens such as C. botulinum • Benefits of MAP are lost once the pack is opened

19. Conclusions • Storage of fish under modified atmosphere conditions; • decrease the production of ATP and its degradation products, • inhibit bacterial growth, • reduce the formation biogenic amine (histamine, cadaverine etc.), • decrease the concentrations of TMA and TVB-N, • extend sensory rejection, • prolong self-life and maintained quality In general, depending on raw materials, temperature, gas mixtures and packaging materials,the percentage of increase in shelf life in MAP ranges from 0% to 280% compared with aerobic storage Addopt from: Dr. Fatih ÖZOĞUL Çukurova University, Faculty of Fisheries