Presentation on theme: "Controlled Atmosphere and Modified"— Presentation transcript:
1Controlled Atmosphere and Modified Atmosphere StorageDr. Ron PoratDept. of Postharvest Science of Fresh ProduceARO, The Volcani Center, Bet Dagan, Israel
2Normal room air contains 21% O2 and 0.03% CO2. 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.
3The 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 O2 and increased CO2 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.
4CA and MA are usually used as a supplement to cold storage, but in some cases they may replace cold storage.
5Potential benefits of CA: Retardation of ripening and senescence.2) Inhibits ethylene effects.3) Reduction of certain physiological disorders.4) Inhibition of pathogen growth.5) May be used for insect control.
6Potential harmful effects of CA: May cause irregular ripening after storage.2) May cause certain physiological disorders.3) May enhance anaerobic respiration and development of off-flavors.4) May cause susceptibility to decay.
7Fruits and vegetables differ in their tolerance to low O2 and to high CO2 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 off-flavors.
8Tolerance of various commodities to low O2 concentrations
9Tolerance of various commodities to high CO2 concentrations
10Fruits 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 pearUp to 6 months – kiwi, persimmon, pomegranateUp to 3 months – avocado, banana, cherry, grape, mango, nectarine, peach, plumUp to 1 month – apricot, fig, papaya, pineapple, strawberry
11CA or MA may be applied to improve the storage potential of either short- or long-lasting commodities.
19Recent 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 5C without the development of CI.
20In 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% O2 and 8-12% CO2).It is possible to improve gas control in MAP by adding absorbers of ethylene, carbon dioxide and oxygen.
41In 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.