Table 1. — Oxygen and carbon dioxide concentrations and temperatures in 

 controlled-atmospliere cabinets 



Cabinet 



Proposed 

 concentration"'- 



Average concen- 

 tration for storage 

 season 



Average temperatiire 



during storage 



season 



no. 



Oxygen 



Carbon 

 dioxide 



Oxygen 



Carbon 

 dioxide 



1 



Percent 

 3 

 3 

 3 



Percent 

 2-3 

 

 



Percent 

 4.4 

 3.2 

 6.2 



Percent 

 2.4 



.3 



.4 



30.6 



2 ; 



29.7 



32 



31.0 







""" Approximate concentration. 



2 Equipped with cannlster containing 1.5 pounds of activated coconut-shell carbon. 



cabinets for C.A. storage. Two boxes of each variety were placed in each of 3 layers, 

 and 1 box of Golden Delicious and 2 of Starking Delicious were placed in the fourth, or 

 top, layer. 



In accordance with Smock's recommendation, the first cabinet was to contain an 

 atmosphere of about 3 percent oxygen and 2 to 3 percent carbon dioxide. The other two 

 cabinets were to contain atmospheres of approximately 3 percent oxygen and no carbon 

 dioxide, in accordance with Fisher's recommendation. One of the latter cabinets was 

 equipped with an activated carbon-adsorption unit. 



The oxygen and carbon dioxide levels in the cabinets were obtained through the nor- 

 mal respiration of the fruit. Excess carbon dioxide was absorbed in a potassium hydrox- 

 ide solution; and if the oxygen fell below a concentration of 3 percent, a small annount of 

 air was allowed to enter the cabinet. Because of leakages in the cabinets and the aerating 

 system, the proposed gas concentrations were not rigidly maintained (table 1). 



Apples of both varieties were held at 31° F. in regular-air storage for comparison 

 with the fruit from the C, A. cabinets; the fruit in regular-air storage was evaluated at 

 intervals by the indices described later. The fruit in C.A. storage was similarly evalu- 

 ated at the end of the season. By this procedure, the retardation of ripening due to con- 

 trolled atmospheres could be evaluated by pairing the quality of the C.A. fruit with fruit 

 withdrawn from regular-air storage. 



The following physical and chemical determinations were made on sample lots of 20 

 fruits: 



1) Firmness - -Magness -Taylor Pressure Tester with 7/l6-inch plunger 



2) Soluble pectins --Modified Carre'-Haynes Method (l) 



3) Total acidity as nnalic acid- -Titration 



4) Hydrogen-ion concentration--Beckman pH Meter 



5) Soluble solids --Refractometer 



6) Reducing 



7) Total sugc 



ng sugarl 

 jugars J 



■Sunnner Method (11) 



- 4 - 



