By Dick Bartram
In 1995, there was over 100 million 42-pound box capacity of controlled atmosphere (CA) storage in Washington State. The commercial application of this technology has permitted a tripling of production and effective marketing of apples (30 million to over 90 million boxes of fresh market apples) and an equal increase in processed apples in the past 20 years. Due to this technology, apples of higher quality can be marketed year-round and can be exported to any country in the world.
The Washington State apple industry was relatively late in the use of controlled atmosphere storage compared to many parts of the United States or world. However, once CA storage began in Washington, its use expanded more rapidly and to a greater volume than any other apple-producing area.
The commercial use of CA storage may seem to be relatively new. However, the first scientific investigation of the effect of atmospheres on fruit ripening appears to have been conducted by Jacques Etienne Berard. He was a professor at the School of Pharmacy at Montpellier in France. His studies were conducted in 1819 and 1820 and published in 1821. Berard recognized that harvested fruits utilize oxygen and give off carbon dioxide. He observed that fruits placed in an atmosphere deprived of oxygen did not ripen as rapidly. There is no record of commercial use of this information for nearly 100 years.
Records show a remarkable use of the principles of CA storage by commercial storage operators took place in 1865 in Cleveland, Ohio. Benjamin Nyce built a reasonably air-tight storage that used ice for cooling and his own special paste for filtering the atmosphere. He operated this storage for a few years but refused to permit others to use his patented procedures. Consequently, there is no record of expanded use of the system.
The next research work on the effect of CA storage on fruit ripening occurred in the early 1890s. The first American scientists to initiate testing were R.W. Thatcher and N.O. Booth of Washington State University. Around 1903, they performed two years of testing that proved promising. However, in 1905 or 1906, Booth left the university, and the work was discontinued.
In the 1907 to 1915 period, research personnel at the U.S. Department of Agriculture and Cornell University worked with several fruits, and their response to both lower oxygen and higher carbon dioxide in storage atmospheres. This work was reported in various scientific journals but did not result in commercial use.
The first truly intensive and systematic research on CA storage was initiated in England in 1918 by Franklin Kidd and Cyril West. Both were associated with the Low Temperature Research Station at Cambridge. Kidd and West initiated laboratory experiments on fruits at Cambridge. Various temperatures and atmospheres were used. Fruits involved were apples, pears, plums, strawberries, gooseberries, and raspberries.
In a few years, their work centered on apples. A new small-scale gas storage was constructed in 1923-24. Improvements were added in the next few years.
In 1927, Kidd and West summarized their work to that date in a classic bulletin on the Gas Storage of Fruit. The atmosphere in the Gas Storage of Fruit was generated by fruit respiration. The gas composition in the storage atmosphere was dependent upon the oxygen consumed and the carbon dioxide evolved by the fruit within a gas-tight building. Kidd and West continued their work and published periodic papers.
In 1930, a new experimental CA facility, the Ditton Laboratory, was built near the East Malling Horticultural Research Station in Kent, England. This was one of the leading fruit growing areas. The first commercial CA storage appears to have been constructed by a grower near Canterbury in Kent in 1929. By 1938, there were over 200 commercial gas storages in England.
Later, Kidd, the more outgoing and publicly visible member of the duo, was knighted for their work toward the development of CA storage.
The work of Kidd and West did not go unnoticed in the United States. The first American group to initiate research on CA storage was at the University of California at Davis. Following these tests at Davis, a commercial test was set up in the fall of 1933 at the National Storage Company in Watsonville, California. The results were successful.
In 1935, Dr. F.W. Allen, who helped start the work at Davis, was joined for about one and a half years by Dr. R.M. Smock. Their research was reported in 1938. In February 1937, Smock moved to Cornell University to take up work in postharvest physiology of fruit.
At Cornell, one of Smock's assistants was Archie Van Doren, a graduate student who was to do his Ph.D dissertation on CA storage. Under Smock's direction, apples, mostly McIntosh, were tested in a variety of CA storage regimes. In 1938, Smock spent three months in England with Kidd and West, continuing testing CA storage of apples. In June 1941, a report of their findings was detailed in a bulletin entitled Controlled Atmosphere of Apples.
The team of Smock and Van Doren added new dimensions to CA storage by the addition of a chemical caustic soda solution to the system for removal of carbon dioxide. This permitted a lowering of the oxygen level and extended storage life. It also permitted storage of cultivars sensitive to higher carbon dioxide levels.
Commercial CA storage of apples in the United States had its early start in New York State and almost entirely in the Hudson Valley with the McIntosh variety. With the encouragement of Smock and Van Doren, the first three CA rooms were put into operation in 1940. In 1940, the Hudson Valley area had 24,000 bushel CA capacity, and by 1949, 100,000 bushel capacity.
Following the early use of CA storage for McIntosh in New York, Dr. Frank W. Southwick, also a Cornell pomology graduate student, developed CA storage in the Massachusetts and New England area. He helped with the building of the first CA storage in that area in 1952.
The third area to run CA tests was in Virginia from 1949-51 under Dr. George Mattus from Virginia Polytechnic Institute. Later, Dr. Donald Dewey, also a student of Dr. Robert Smock at Cornell, developed CA storage of Jonathan apples in Michigan.
Commercial CA storage began in Yakima, Washington, in 1957 when Stubbs-Lamb Fruit Company constructed a polyester tent placed in an old refrigerated storage. Dr. Archie Van Doren was an active participant in this major commercial test. The Washington State
Apple Commission, Fruit Industries Research Foundation, DuPont De Nemours and Company, and Hooker Chemical Company, all cooperated in designing and constructing this first Washington State CA room. The eight carloads of apples in this storage were a success.
By the late 1960s, the volume of CA storage in Washington reached three million boxes. During the 1970s, this capacity grew to 20 million boxes. As a result of these new CA storages, the sale and shipment of apples after April 1 tripled from four to over 11 million boxes.
The original reduction of oxygen in CA storage was dependent on the natural respiration of the fruit. C02 increased in this respiration process and had to be scrubbed from the atmosphere by using caustic soda. In North America, the use of hydrated lime for removing C02 was developed by Charles Eaves of Nova Scotia, Canada.
The Whirlpool Corporation, makers of household washers, driers, and refrigerators, tried to develop small generators for household food preservation with the use of controlled atmosphere along with refrigeration. This effort did not prove successful but resulted in the Whirlpool Corporation building larger generators (Tectrol units) for apple CA storages.
In 1962, Dr. Donald Dewey and Dr. George Mattus cooperated in testing generated CA atmosphere storages. This lead to widespread use of CA storage of apples and many other crops.
In the years following Tectrol units, many additions and changes have been applied to the creation of CA atmosphere for apples and other foods. "COB" units were popular in the 1970s and early 1980s. "Isolcell" units were used in new storages by 1985.
Tectrol, COB, and Isolcell units used the combustion of propane or natural gas to develop atmosphere low in oxygen.
"Oxydrain" units were introduced from the Netherlands in the early 1980s. This was a novel concept in which ammonia was cracked or split into nitrogen and hydrogen gases. The nitrogen gas was used to displace storage air to lower oxygen and carbon dioxide levels.
Economic and safety concerns have shifted to on-site generation of nitrogen away from combustion systems. Pressure Swing Adsorption (PSA) and selective gas-permeable membranes are current new methods for separating nitrogen, oxygen, carbon dioxide, and other gases from nitrogen.
These above improved systems were a few of the many innovations that were applied to the rapid application of CA in Washington State. Selected and segregated harvest procedures with rapid application of CA atmospheres (two to three days after harvest oxygen below 3%) were goals developed. In the 1984 Washington State Horticultural Association Proceedings, Drs. Ken Olsen, USDA-ARS, Wenatchee, Washington; Sam Lau, British Columbia, Canada; and Paul Chen, Mid-Columbia Experiment Station, Hood River, Oregon, have detailed reports of refined methods of handling apples from the Pacific Northwest in CA storage.
The research and commercial use of CA storage for apples continues to be improved. The correct combination of oxygen, carbon dioxide, temperature, and humidity for each variety can still be improved as new varieties such as Fuji, Gala, Braeburn, and Jonagold take their place in the market. In the future, storage disorders such as superficial scald and some decay organisms may be controlled with proper harvest maturity and storage in low oxygen and correct carbon dioxide levels. The levels of disease and insect control provided by different atmospheres have yet to be determined.
The development of CA storage was conceived and nurtured through research conducted around the world by government, universities, and industry. The research led to dramatic engineering and technological developments and building construction. It has led to an extended apple, pear, and cherry marketing season and worldwide marketing.
Copyright © 1996, Good Fruit Grower
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