GENERAL INFORMATION 



147 



The maxiiniim temperature employed with any variety of apples is 

 40° F. This requires insulation and refrigeration equipment just as 

 with cold storage. Modified atmosphere storage should be regarded as a 

 supplement to cold storage. 



Advantages of This Type of Storage. The following advantages are 

 to be realized in the use of this system: 



1. Many varieties of apples are subject to low-temperature troubles 

 such as brown heart, internal browning, and brown core. By using 

 temperatures from 38 to 40° F. and the proper atmosphere, these 

 varieties can be kept just as long as if not longer than at 32° and will be 

 free from these disorders. 



2. With some apple and pear varieties, temperatures as low as 34° F. 

 can be employed and storage life is very greatly lengthened. For 

 example, Kidd and West have shown that Bartlett pears normally can 

 be kept about eight weeks in cold storage at 34° F. In modified 

 atmosphere storage they can be kept satisfactorily seven months at 

 34° F. 



3. A specific effect of carbon dioxide is greatly to retard the normal 

 green to yellow change in apples and pears. This is of great importance 

 in storage of varieties of green cooking apples. 



4. A marked residual effect of storage is noticed as a result of this 

 scheme. Fruit removed from storage will remain marketable much 

 longer than that removed from cold storage. 



5. Because of the inhibitory effect of carbon dioxide on mold growth, 

 somewhat higher humidities can be used in modified atmosphere stor- 

 age than in cold storage. This means less fruit shriveling during 

 storage. 



Disadvantages of This Type of Storage, 1. Because of the danger of 

 suffocation and of loss of the required atmospheric concentrations of 

 carbon dioxide and oxygen, operators cannot enter the chambers for 

 inspection of the fruit or manipulation of equipment. Hence, fruit is 

 periodically examined by reaching through the ventilating port. Since 

 the chamber cannot be opened until the storage season is over, the fruit 

 to be marketed in each marketing period is put in separate chambers. 



2. It is difficult to construct buildings gas tight. In spite of the sheet- 

 metal linings and vaseline-sealed joints, in even the best-constructed 

 modified atmosphere storages, there is a leakage of 6 percent per day, 

 or more. 



3. As has been stated, modified-atmosphere storage is not univer- 

 sally applicable to all fruits or all varieties of any one fruit. 



4. The double effect of low temperatures plus atmospheric control 

 cannot always be expected to give the full theoretical benefit that might 



