Fruit storage
As a fruit storage is referred to the appropriate storage of fruits to provide a long shelf life. In the course of advancing technology, the methods were continuously optimized.
introduction
The original methods of preservation for long-term storage of perishable foods are drying , salting , sterilizing and smoking , which are still used today for meat , fish and some fruits. Fruit and vegetables were also kept moist and cool in earth pits and cellars. The duration of storage depended on the shelf life, ie on the metabolism of the goods and on the storage conditions. Some of the old methods are still used today, as specialties such as smoked ham , pickled cucumbers or raisins have developed from them .
Cold store
Cold stores or freezers with mechanical cold generation are the successors to the ice cellars that were cooled with natural ice. It can be used to store frozen food for long periods of time. This is more difficult with foods such as fresh fruit and vegetables, as they suffer when the temperature falls below typical species and often become inedible. Therefore, they can only be stored or transported for a short time. The storage of menopausal fruits and vegetables is particularly difficult . There are two stages of maturity , the maturity to pick and the maturity to eat. Well-known representatives are z. B. pears, strawberries, bananas and avocados .
A longer storage period is possible by reducing the metabolism at high humidity and lowering the temperature to the lower temperature typical of the species. If the oxygen and carbon dioxide content of the surrounding atmosphere are also influenced, the storage period can be extended further. If only one of the two sizes is optimized, one speaks of one-sided storage (Modified Atmosphere MA), both sizes are optimized by two-sided storage ( Controlled Atmosphere CA). In the beginning one also spoke of one or two-sided gas storage. In addition to the cooling equipment, the prerequisites for these storage technologies are gas-tight storage facilities and technical equipment for generating nitrogen, removing carbon dioxide and the corresponding measurement and control technology.
MA or CA - cold storage
The Controlled Atmosphere (CA) is a storage technique that historians report that it was used a few thousand years ago in China and Egypt for inventory management in large storage facilities. The oxygen content (O 2 ) in the atmosphere of the storage rooms was lowered by natural processes and the carbon dioxide content ( CO 2 ) increased, which extended the shelf life of the goods and killing pests and limiting their activity and reproduction.
These storage technology has been in the 20th century with various technical methods such as catalytic combustion, by alternating pressure equipment ( Pressure Swing Adsorption PSA), membrane technology , O 2 - Scrubber and ethylene converter developed, improved and combined with engine cooling camps. Since the 1950s, it spread quickly in Germany. This enabled extremely long storage and transport times for some types of fruit and vegetables; the energy price (e.g. electricity price ) can be a limiting factor .
Experience in CA storage, experiments by fruit growing research institutes and advances in gas measurement technology have led to ULO storage (ULO = Ultra Low Oxygen ). The oxygen content of the storage atmosphere is greatly reduced; the optimal carbon dioxide content is also precisely adhered to.
So z. B. the predominant part of the German harvest of table apples stored under CA; this enables a long supply of the population.
CA technology in transport
About half of the bananas imported into Germany are transported using this method, mainly in CA refrigerated ships , but also in CA refrigerated containers . The green bananas only convert starch into sugar in so-called ripening houses in Germany and acquire their yellow color in the process. Also in other areas of fruit transport, such as B. Apples from New Zealand, cherries, plums, avocado, papaya and mango from South America, CA is used. It is currently being investigated which types of cut flowers can be imported using this transport technology on ships instead of airplanes.
The major vertically structured banana companies Chiquita ( Great White Fleet ), Dole and Noboa ( Ecuadorian Lines ), which use CA on a large scale in their refrigerated ship fleets, have also convinced other companies of the advantages of this transport technology. In some cases directly, as the division of labor among the various companies repeatedly came about, particularly under the influence of the European banana market organization. Bananas were then also transported under CA in the modern refrigerated ships of the Great White Fleet or Ecuadorian Lines for other companies. The low reject rate (Turner) and the excellent quality of the fruit spoke for themselves. The end customers are rarely informed about the storage and transport methods. In Germany, for example, the advantages "stored under CA" or "transported under CA" are not advertised.
literature
- G. Drews: Ventilation and air conditioning of ship holds . Dissertation, Technical University of Hanover, 1970.
- Karl-Heinz Hochhaus, L. Idler, Y. Wild: Reefer containers and controlled atmosphere in ship transport . Shipyards Handbook, 1992.
- Y. Wild: Simulation of CA Plants for Optimizing the Energy Consumption; 6th International Controlled Atmospheres Conference , Ithaca NY (USA) 1993. p. 292 ff.
- Karl-Heinz Hochhaus: German refrigerated shipping (1902-1995) . Bremen 1996, ISBN 3-931785114 .
- http://hochhaus-schiffsbetrieb.jimdo.com/k%C3%BChlladen-und-container-228/