to scald has been reviewed by Porritt (62) and that of ethylene and nonethylenic 
volatiles to scald by Pentzer and Heinze (57). (See also section on Scald.) 
For the removal of volatiles and other odors in air purification studies, 
activated carbon has been used to a considerable extent (17, 32, 35, 42, 69, 
77, 82, 84). However, activated carbon has been found to be ineffective as an 
absorbent for ethylene (12, 22, 23, 24, 42, 54, 59, 60, 77). Brominated acti- 
vated carbon absorbs both ethylene and nonethylenic volatiles (18, 23, 77), but 
its efficiency decreases rapidly and it is very corrosive (18). 
Ozone (12, 18, 32) and chlorine (18, 32) have also been used for air 
purification. Though both reduce the volatiles present, ozone may injure the 
fruit (18, 67) and chlorine may produce off-flavors and cause the fruit to 
develop a poor appearance (18). 
The use alkaline potassium permanganate has been suggested for the re- 
moval of apple storage volatiles (43, 44), but in at least one investigation 
(89) in which it was used it failed to reduce the level of volatiles, did not 
reduce scald, nor delay softening of the fruit in storage. 
Scrubbing the storage atmosphere with water has been found to effectively 
remove fruit volatiles by some (1, 42) but not by others (4, 15). The negative 
results were obtained in storage atmospheres having a very low ethylene concen- 
tration to begin with. In an earlier report Grierson-Jackson (29) pointed out 
that water condensing on the refrigeration coils of cold storage rooms may re- 
move volatiles; in air purification tests, therefore, it is important to specify 
the type of refrigeration in use in the rooms under study. 
Many compounds have been identified in apple volatile emanations. These 
are summarized in the reviews cited (57, 83), in a report on apple biochemistry 
(41) and in several papers concerned with the volatiles given off by apples or 
acturring in apple storages: (16, 35, 36, 37,49, 50, 51,°79). 
Methods used in the analyses of apple volatiles have included biological 
assays (primarily for ethylene) (14), combustion (64), and oxidation with ceric, 
permanganate, or chromic reagents (22, 33, 16, 64). Partition chromatography 
(35), paper chromatography, and spectrophotometry have also been used (38, 49, 
50) as has mass (37) and infrared spectrophotometry (39, 81). More recently 
gas chromatography has been used to determine ethylene (7, 8, 51, 52, 53), as 
well as other volatiles (28). In addition to details provided in these reports, 
the articles by Burg (11) and Meigh (48), and the reviews of Porritt (62), Burg 
(10), and Ulrich (83) discuss the older as well as the newer methods used in 
analyses for ethylene or nonethylenic volatiles. 
Research on apple volatiles has included measurements of the rate of 
production of these volatiles (23, 25, 34, 58, 80) and estimates of the vola- 
tile levels that might be found in apple storage rooms (4, 15, 63, 66). One 
such estimate (66), based on the analyses of the atmospheres of 30 commercial 
storage rooms, gave a range in concentration for ethylene of 2 to 100 ppm and 
for nonethylenic volatiles of 2 to 20 mgs. per cu. ft. (expressed as mgs. Ce 
(S04) 5 reduced). 
In controlled atmosphere storages (CA or gas storage) the production of 
volatiles by apples is reportedly reduced (50, 63, 75, 76). Though production 
of volatiles is reduced, the concentrations developed within the CA storage 
room may be greater than that occurring in a regular cold storage because of 
the gastight room (unless provisions for volatile removal have been made). 
Fidler (18), for example, found ethylene levels ranged from 50 to 400 ppm in 
some of his gas storage studies. Fidler also reported (16) that the concen- 
tration of ethylene always exceeded that of the other organic volatiles in gas 
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