Modified atmosphere is a common technical definition that describes the practice of modifying the composition of the internal atmosphere of a package (commonly food packages, but this technique is also used for drugs) in order to improve the shelf life. Shelf-life is the length of time that corresponds to a tolerable loss in quality of a processed food. ...

The modification process often tries to lower the amount of oxygen (O₂), moving it from 20% to 0%, in order to slow down the growth of aerobic lifeforms and the speed of oxidation reactions. The removed oxygen can be replaced with nitrogen (N₂), commonly acknowledged as an inert gas, or carbon dioxide (CO₂), which can lower the pH or inhibit the growth of bacteria. General Name, Symbol, Number Oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16 (VIA), 2, p Density, Hardness 1. ... Aerobic is an adjective that means requiring air (where air usually means oxygen). ... The most fundamental reactions in chemistry are the redox processes. ... General Name, Symbol, Number Nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15 (VA), 2 , p Density 1. ... Carbon dioxide is an atmospheric gas composed of one carbon and two oxygen atoms. ... PH or ph or pH or Ph may be: In chemistry, pH is a measure of acidity. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria is also the fictional name of a warring nation under Benzino Napaloni as dictator, in the 1940 film The Great Dictator...

Scientific terms

• MAP = Modified atmosphere packaging
• EMAP = Equilibrium modified atmosphere packaging

History

Controlled Atmosphere Storage (CAS) was used already in the 30’s, when ships transporting fruits had high levels of CO₂ in their holding rooms, thus increasing the shelf-life of the product. In the 70’s MA packages reached the stores when bacon and fish were sold in retail packs in the UK. Since then the development has been stable and the interest into MAP has grown due consumer demand. This has led to advances for example in the design and manufacturing of polymeric films. New techniques are designed, like the use of anti-fogging layer to improve product visibility. From MAP a new packaging technique - EMAP has been developed. The growing popularity of EMAP vegetables and fruits can be explained with the behaviour of the modern consumer who demands fresh vegetables and fruits which have a long shelf-life without the use of preservatives.

Products

Under MA products like red meat, seafood, minimally processed fruits and vegetables, pasta, cheese, bakery goods, poultry, cooked and cured meats, ready meals and dried foods are packaged. The three major commodity types are fruits and vegetables, meat and meat products and seafood. It has been estimated that 25-40 % of all fresh produce harvested will not reach the consumers table, due to spoilage and mishandling that occurs during distribution. Meat is animal tissue (mainly muscle) used as food. ... Seafood in Brussels, Belgium Seafood is any sea animal that is served as food or is suitable for eating. ... In botany, a fruit is the ripened ovary, together with its seeds, of a flowering plant. ... Vegetables on a market Vegetable is a nutritional and culinary term denoting any part of a plant that is commonly consumed by humans as food, but is not regarded as a culinary fruit, nut, herb, spice, or grain. ...

Modified Atmosphere Packaging (MAP)

Modified Atmosphere Packaging (MAP) is a technique used for prolonging the shelf-life period of fresh or minimally processed foods. In this preservation technique the air surrounding the food in the package is changed to another composition. This way the initial fresh state of the product may be prolonged. It is the shelf-life of perishable products like meat, fish, fruits and vegetables that will be prolonged with MAP since it slows the natural deterioration of the product. MAP is used with various types of products, where the mixture of gases in the package depends on the type of product, packaging materials and storage temperature. Meat and fish need very low gas permeability films so for non-respiring products (meat, fish, cheese etc.) high barrier films are used. The initial flushed gas-mixture will be maintained inside the MA package. But fruits and vegetables are respiring products where the interaction of the packaging material with the product is important. If the permeability (for O₂ and CO₂) of the packaging film is adapted to the products respiration, an equilibrium modified atmosphere will establish in the package and the shelf-life of the product will increase. This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...

Equilibrium modified atmosphere packaging (EMAP)

Among fresh-cut produce Equilibrium Modified Atmosphere Packaging (EMAP) is the most commonly used packaging technology. When packaging vegetables and fruits the gas atmosphere of package is not air (O₂ 21%; CO₂ 0.01%; N₂ 78%) but consists usually of a lowered level of O₂ and a heightened level of CO₂. This kind of package slows down the normal respiration of the product and so prolongs the shelf-life of the product. Of course there are other factors like the size of the product, severity of preparation, maturity of the product and type of tissue that have an effect to the shelf-life of an EMA packaged produce.

Technology

There are two techniques used in the industry to pack vegetables namely gas-flushing and compensated vacuum. For its cheapness the gas-flushing is more widely used. In gas-flushing the package is flushed with a desired gas mixture, as in compensated vacuum the air is removed totally and the desired gas mixture then inserted.

Gases

The atmosphere in a MA package consists of N₂, O₂, CO₂. It is the altered ratio of these gases that makes a difference in the prolongation of shelf life. By reducing the O₂-level and increasing the CO₂-level, ripening of fruits and vegetables can be delayed, respiration and ethylene production rates can be reduced, softening can be retarded and various compositional changes associated with ripening can be slowed down. Ethylene or ethene is the simplest alkene hydrocarbon, consisting of two carbon atoms and four hydrogens. ...

Oxygen is essential when packaging fresh fruits and vegetables as they continue to respire after harvesting. The absence of O₂ can lead to anaerobic respiration in the package which accelerates senescence and spoilage. Too high levels of O₂ do not retard respiration significantly and it is around 12% of O₂ where the respiration rate starts to decrease. So oxygen is used in low levels (3-5 %) for positive effect. When packaging meat and fish, the high CO₂-levels are effective bacterial and fungal growth inhibitors. In the case of vegetables and fruits, CO₂ is not a major factor since CO₂-levels above 10% are needed to suppress fungal growth significantly. Unfortunately higher levels than 10% of CO₂ are working phytotoxic for fresh produce. Nitrogen is used as a filler gas since it neither encourages or discourages bacterial growth. Anaerobic is a technical word which literally means without air. ...

Packaging Films

When selecting packaging films for EMAP of fruits and vegetables the main characteristics to consider are gas permeability, water vapour transmission rate, mechanical properties, transparency, type of package and sealing reliability. Traditionally used packaging films like LDPE (low density polyethylene), PVC (polyvinyl chloride), EVA (ethylene vinyl acetate copolymer) and OPP (oriented polypropylene) are not permeable enough for highly respiring products like fresh-cut produces, mushrooms and broccoli. As fruits and vegetables are respiring products, there is a need to transmit gases from and to the package. Films designed with these properties are called permeable films. Other films, called barrier films, are designed to prevent the exchange of gases and are mainly used with non-respiring products like meat and fish. Polyethylene or polyethene is one of the simplest and most inexpensive polymers. ... The chemical compound polyvinyl chloride Irregular heartbeat: premature ventricular contraction In frame relay and X.25 a permanent virtual circuit This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... EVA or Eva may refer to: Extra-vehicular activity, also known as a spacewalk. ... Opp is a city located in Covington County, Alabama. ...

References and sources

• CHURCH, I.J. & PARSONS, A.L.: (1995) Modified Atmosphere Packaging Technology: A Review, Journal Science Food Agriculture, 67, 143-152
• DAY, B.P.F.: (1996) A perspective of modified atmosphere packaging of fresh produce in Western Europe, Food Science and Technology Today, 4,215-221
• PARRY, R. T.: (1993) Principles and applications of MAP of foods, Blackie Academic & Professional, England, 1-132
• PHILLIPS, C.A.: (1996) Review: Modified Atmosphere Packaging and its effects on the microbial quality and safety of produce, International Journal of Food Science and Tech, 31, 463-479
• ZAGORY, D. & KADER, A.A.: (1988) Modified atmosphere packaging of fresh produce, Food Technology., 42(9), 70-77