STORAGE OF FRUITS, VEGETABLES, AND FLORISTS' STOCKS 3 



circular and in greater detail in other publications (8, 14, 22, 38, *¥>, 



53, 72, 77, 78, 79, 80, 82, 83, 8k, 85, 86, 88, 95, 98, 109, 110, 112) . 2 



FACTORS INVOLVED IN COLD STORAGE 



Kecommendations for the best conditions for the storage of fresh 

 fruits, vegetables, and cut flowers are subject to change from time to 

 time as more definite information is gained in the handling of these 

 commodities. The conditions and requirements given in this circular 

 are derived from the best commercial practice at the present time 

 and from scientific experimentation. The term "cold storage" as 

 used in this circular refers to storage where temperatures in the ap- 

 proximate range of 25° to 45° F. are maintained by mechanical means 

 or by the use of ice and salt ; "freezer storage" to temperatures rang- 

 ing from about 15° to —20°, usually close to zero; "cool storage" to 

 temperatures ranging from about 50° to 65°, or possibly 70° ; "un- 

 ref rigerated storage" to temperatures that are allowed to fluctuate with 

 outside temperature ; and "common storage" to storage in which the 

 temperature best suited to the commodity is obtained as nearly as 

 possible by insulation and ventilation only. 



All of the temperature requirements are given in degrees Fahrenheit 

 and represent the average air temperatures that should be maintained. 

 The humidities are relative and are expressed in percentage of satura- 

 tion ; for example, when it is stated that a certain humidity should be 

 85 percent, this means that the air should be at approximately 85 per- 

 cent of complete saturation with water vapor at the recommended 

 temperature. Allowance has been made for the facts (1) that the 

 temperature of fruits and vegetables in transit is usually higher than 

 the recommended storage temperature, (2) that, except during winter 

 weather, ripening or other changes are likely to go on more rapidly 

 during a given transit period than during the same length of time 

 in cold storage, and (3) that when the commodities arrive at destina- 

 tion, even if they had been in storage at shipping point, they are likely 

 to be somewhat more mature than if they had remained in storage the 

 whole time. 



Temperature of Storage Rooms 



If the best results are to be obtained in the cold storage of the prod- 

 ucts discussed herein, it is highly important that the temperature in 

 storage rooms be held fairly constant. Variations of 2° or 3° F. 

 above or below the desired temperature are in most cases too large. 

 They can usually be avoided if the storage rooms are well insulated 

 throughout and have adequate coil surface and if the spread be- 

 tween the temperature of the refrigerant and that of the room to be 

 refrigerated is kept small. For example, in a room where 45° is 

 the desired temperature, using ammonia evaporating at about 26° 

 in the coils, fluctuations of ±1%° may occur in the air temperature 

 in the room; whereas at 32°, with ammonia also at 26°, fluctuations 

 in the room temperature are usually less than ±%°. However, 



2 Italic numbers in parentheses refer to Literature Cited, p. 54. 



