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AIR PURI FICATIO N FOR LBNGTHEIIIIIG THE STORAGE LIFE OF APPLES 



Following is a progress report on this interesting subject, prepared 

 by R. M. Smock and F. T,'. South.wick of Cornell University. 



Purposes of Air Purification 



1. To remove foul odors in the storage room which may contaminate the 

 apples and hence reduce their eating quality. 



2. To remove the ethylene generated by ripening apples. Study has shown 

 that as fev/ as one percent of the apples in a storage chamber if ripe 

 T/ill tend to ripen up the rest of the apples in the room, 



3. To remove scald gases. Scald is caused by accuraulations of certain 

 gases generated by the fruits. 



Methods of Air Purification Used Heretofore in Apple Stor_age 



1. Some attempts have been made to reduce the odor level by the use of ozone, 

 OzOne is of benefit primarily in reducing the growth of surface molds on 

 the fruits or containers. Ozone has been found to merely mask and not 

 destroy many odors in an apple storage. 



2. There have been no comaaercially feasible methods heretofore of removing 

 naturally generated ethyJ.ene. 



3. Scald gases have heretofore been removed by wrapping the apples in paper 

 impregnated with mineral oil or placing shreds of such paper in the pack- 

 age. There are enough objections to the use of oiled paper to justify 



a search for a better and more convenient method of scald control. 



Principles In volved in Air Purific ation 



Many gases can be "adsorbed" on the surfaces of specially prepared 

 activated carbon pdmilar to that used in a soldier's gas mask. The Cornell 

 trials have made use of this fact. The storage atmosphere is passed through 

 a bed of activated carbon and then the "purified" atmosphere is circulated 

 to ail parts of the room. Ethylene seems to be removed from the atmosphere 

 more completely if the activated carbon is impregnated with a strong oxidiz- 

 ing agent like bromine. The use of bromine has resulted in considerable cor- 

 rosion of the canisters containing tiie activated carbon, however. Until 

 a substitute for bromine can be found, impregnation with special materials 

 will not be done in most comiaercial tests for 1945-46. The use of un- 

 brominated carbon has given very promising results. It is felt that better 

 resulijs v/ill be had when something as pov/erful as bromine can be success- 

 fully impregnated in the activated carbon. 



Results o f 1944-45 Tests 



During the 1944-45 storage season ten tests were conducted on a 

 commercial scale in cold storages around New York State. Only one of these 

 storages had an acute odor contamination problem, but in this one storage 

 the odor problem was solved by use of air purification. A careful study 

 of differences in softening (ripening rate) was possible in only six of 

 these ten tests. In these six tests the ripening rate of apples was sig- 

 nificantly retarded (as compared with apples in control room) in four cases. 



