Controlled Atmosphere

Every vegetable undergoes metabolism. That means that every fruit is alive and breathes, consuming oxygen, not only while growing, but also after harvest. The respiration process can be described as the breakdown by oxidation of carbohydrates such as starch, sugars and acids, which are present in the vegetable tissues. The products of respiration are heat, carbon dioxide, water vapour and some aromatic compounds.

The higher the rate of respiration of a fruit, the more rapid will be its senescence and deterioration with a subsequent reduced storage life. The use of cold, for a long period of time, have been the only method used in the preservation of fresh fruits and vegeatables.

For a long time, refrigeration was the only method used to store fresh fruit and vegetables.It was not until 1821, biologist Berard discovered that the metabolism of fruit and vegetables was slower when kept at low oxygen concentration. At the beginning of the 20th century, it was through the research of scientists KIDD and WEST, that C.A. storage became a defined scientific subject. However, the real commercial boom of C.A. took place simultaneously in Europe and in the U.S.A. at the end of the '50s.

The combined action of a lower concentration of oxygen and a higher concentration of carbon dioxide in the storage room considerably reduces respiratory activity.

Controlled Atmosphere, together with temperature reduction, has a greater effect on the vegetables' metabolism by reducing, for example, ethylene production of the fruit, by stopping the loss of chlorophyll (green colour) and by delaying pectin hydrolysis (maintaining flesh firmness), thus slowing the breakdown of vitamins and acids.

From a commercial point of view, this means not only preserving the organoleptic qualities of the produce, but also reducing losses due to pathogens (fungi) and to well-known physiological disorders such as common and senescent scald and the appearance of chilling injuries. These advantages become even more evident when more elaborate techniques first applied in Italy by Isolcell are used. We refer to the techniques of "Rapid C.A." and "U.L.O."

The first consists in a very rapid reduction of oxygen in the room (from 21 % to 5% in 36 hours). The U.L.O. atmosphere (Ultra Low Oxygen) results in produce stored in an atmosphere with an oxygen concentration of about 1 %. The choice of atmosphere depends on the type of produce (commodity and variety) and on its physiological state at the time of harvest.

Compared to traditional C.A. storage, the main advantages of U.L.O. storage are a further reduction of the rate of respiration and metabolism (30%) and, especially in the case of apples and pears, the control of some important physiological disorders such as scald, internal breakdown and maintenance of flesh firmness, thus leading to longer shelf-life.

Recently a new storage technique has been developed. Called “dynamic” technique, it is based on a further reduction of oxygen in the storage room until the fruit reaches its tolerance limit. To get this result ISOLCELL ITALIA has developed very sophisticated equipment such as the Intelligent Carbon Dioxide Scrubber (IS).