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Controlled Atmosphere and Modified Atmosphere Storage Dr. Ron Porat Dept. of Postharvest Science of Fresh Produce ARO, The Volcani Center, Bet Dagan, Israel
Normal room air contains 21% O 2 and 0. 03% CO 2. However, it was found that low oxygen and high carbon dioxide levels slow ripening, reduce the development of some peel disorders and inhibit pathogen growth.
The terms controlled atmosphere (CA) and modified atmosphere (MA) imply using an atmospheric compositions that is different from air, but they differ in the degree of their control of the gases concentrations. Control atmosphere (CA) – generally refers to decreased O 2 and increased CO 2 concentrations, by a precise control of the gas composition. Modified atmosphere (MA) – is used when the control of the storage atmosphere is not closely controlled, such as in plastic film packaging.
CA and MA are usually used as a supplement to cold storage, but in some cases they may replace cold storage.
Potential benefits of CA: 1) Retardation of ripening and senescence. 2) 2) Inhibits ethylene effects. 3) 3) Reduction of certain physiological disorders. 4) 4) Inhibition of pathogen growth. 5) 5) May be used for insect control.
Potential harmful effects of CA: 1) May cause irregular ripening after storage. 2) 2) May cause certain physiological disorders. 3) 3) May enhance anaerobic respiration and development of off-flavors. 4) 4) May cause susceptibility to decay.
Fruits and vegetables differ in their tolerance to low O 2 and to high CO 2 concentrations. Extreme oxygen and carbon dioxide concentrations (above the limits for each cultivar) may cause physiological and pathological deterioration, interrupt with normal ripening and enhance anaerobic respiration and development of offflavors.
Tolerance of various commodities to low O 2 concentrations
Tolerance of various commodities to high CO 2 concentrations
Fruits and vegetables can be grouped according to their storage potential under optimum temperature, RH and CA conditions as followed: Up to 1 year – apple and pear Up to 6 months – kiwi, persimmon, pomegranate Up to 3 months – avocado, banana, cherry, grape, mango, nectarine, peach, plum Up to 1 month – apricot, fig, papaya, pineapple, strawberry
CA or MA may be applied to improve the storage potential of either short- or long-lasting commodities.
Use of CA for short-term storage
Transportation of strawberries in CO 2 – enriched atmosphere – Trans. Fresh (Tectroll) technology
Use of CA for long-term storage
CA recommendations A CD-ROM entitled: “CA Recommendations (2001)” was published by the University of California, Postharvest Technology Center. The CD-ROM can be ordered through website access at http: //postharvest. ucdavis. edu.
Acta Hortic. (2003) 600: 737 -740 The above recent publication from the 8 th Int. CA Conference (2002) provides a list of the optimal CA conditions for 35 selected horticultural commodities.
Recent developments in CA storage: Recent improvements include maintaining CA during transport in refrigerated marine containers - this allows to continue the CA chain of apple, pear and kiwi during transport. CA transport of banana permits the harvest at a more fully-mature stage. CA transport of avocado permits to use a lower temperature of 5 C without the development of CI.
In addition to CA, there is also a continuing increase in the use of plastic films and MAP. The greatest use of MAP is for fresh-cut products (to maintain 2 -5% O 2 and 8 -12% CO 2). It is possible to improve gas control in MAP by adding absorbers of ethylene, carbon dioxide and oxygen.
Use of MAP for fresh-cut produce
Fresh-cut lettuce in MAP
Fresh-cut fruit in MAP
The commodity and its environment: Model for gas exchange
Modified Atmosphere Packaging (MAP)
Commercial MAP of banana fruit
Banana – individual bags
Commercial MAP of kiwi
Commercial MAP of broccoli
Commercial MAP of apples
Commercial MAP of cherries
Commercial MAP of grapes
Individual seal packaging of oranges China, 2007
MAP of mangoes Bangkok, 2007
MAP of apples Bangkok, 2007
MAP of peppers Bangkok, 2007
Pallet of Mango fruit covered with PE
Gas permeability of various plastic films
Perforated bags Bangkok, 2007
In addition to gas exchange properties, new polymeric films have been developed with various water vapor transmission rates, which allow to control the RH inside the package and to avoid problems caused by water condensation.
Water condensation inside MAP
Effects of different MA films on water condensation
Effects of different MA films on water condensation
Water condensation and decay development Bangkok, 2007
Water condensation in fresh-cut pineapple Thailand, 2011
In commercial practice, CA is applied especially in apples and pears, whereas MA is successfully applied in a wide range of produce
The following pictures explore some applicable uses of CA and MAP storage:
Effects of MAP on the inhibition of ripening in Mango fruit
Effects of MAP on the quality of pomegranate fruit
Inhibition of senescence and of ethylene effects by CA in parsley
Inhibition of senescence by MAP in parsley
Inhibition of senescence by MAP in broccoli
Inhibition of senescence by MAP in squash
Inhibition of leaf senescence by MAP in radish
Inhibition of sprouting by MAP in radish
Thank you for your attention!