storage, estimating ethylene to constitute 70 to 80 percent of the total vola- 
tile output (20). Other researchers have also found ethylene to be produced ia 
far greater amounts than the nonethylenic volatiles (40, 51). 
In their studies on the physiology of ethylene formation in apples, Burg 
and Thimann (8) found the optimum temperature for ethylene production to be * 
32° C. (87.8° F.), above which it fell rapidly. Southwick (76) reported in 1945 
that McIntosh apples held at 32° F. emitted about half as much volatile material 
as similar fruit held at 40°. 
In apple tissue experiments, decreasing the oxygen concentration to 2.5 
percent resulted in a 50 percent reduction of both ethylene production and res- 
piration, and under completely anaerobic conditions the production of ethylene 
ceased almost immediately (8). Increasing amounts of carbon dioxide decreased 
production of ethylene by apples (5). 
Apples or parts thereof have been used in many experiments designed to 
learn something about the metabolic pathway or source of ethylene formation 
(2, 4, 6, 9, 45, 46). The results given in these papers along with the reviews 
previously cited (3, 10, 57, 62, 88) provide an adequate summary of the current 
status of research in the field of volatiles, particularly ethylene, as carried 
on with apples and other biological materials. 
Literature Cited for Volatiles and Atmosphere Purification in Storage 
1, Antoniani, C., Monzini, A., and Kaderavek, G. P. 
1959. The Problem of the Respiration Products of Fruit Kept in Cold 
Storage. V. New Tests of Adsorption of Volatile Compounds Produced by 
Fruits During Their Storage, Ann. della Sper. Agr. (Rome) 13(5):945- 
948, (English summary.) 
2. Behmer, M. 
1958. Carbon Dioxide and Ethylene Exchange in Stored Apples. Mitt. 
Klosterneuburg, Ser. B, 8:257-273. 
3.7 “Biale,-J% Bi. 
1950. Postharvest Physiology and Biochemistry of Fruits. Ann. Rev. 
4. Buchloh, G. 
1956. The Effect of "Air Washing" on Apple Storage. Angew. Bot. 30:169- 
184. 
Dd. Burg, ‘So Pe 
1958. The Biogenesis of Ethylene. Doctoral Thesis, Harvard Univ. 
1959, Tracer Experiments on the Formation of Ethylene by Apple Tissue. 
Arch. Biochem. Biophysics 84:545-546. 
ie and Stolwijk,* J. AcwSi. 
1959. A Highly Sensitive Katharometer and Its Application to the Measure- 
ment of Ethylene and Other Gases of Biological Importance. Jour. 
Biochem. and Microbiol. Technol. and Engin. 1(3):245-259. 
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