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 3060% 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 CO2s 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 (8090%) 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 50100% in storage life is usually observed, and for cooked shellfish a shelf-life extension of 100200% 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 12C 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 (4C) 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 lm 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 50400% 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 benets 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.