STORAGE 



STORAGE 



3253 



organism. Contrary to common belief, the life pro- 

 cesses do not cease when the fruit is removed from the 

 parent plant. These processes continue until the life 

 cycle of the organism is completed. The fruit organ- 

 isms respire and transpire just as plants do and the 

 measurement of the end products of these respiration 

 and transpiration processes serves as an index of the 

 rate at which the life activities are proceeding. Definite 

 measurements on a large scale show that the tempera- 

 ture factor is the most important from the standpoint 

 of the rate at which the life activities proceed. Each 

 fruit organism has a definite life span or life cycle, and 

 it is easy to see that if in any way these activities can 

 be retarded, the life span can be lengthened. The 

 reduction of the temperature of the organism materially 

 reduces the life processes, and the rates at which these 

 activities proceed is slackened to such an extent that 

 the definite life functions of the organism may con- 

 tinue slowly during a long period. The retardation 

 of the life activities through the reduction of the tem- 

 perature thus induces a slowness of the rate and a con- 

 sequent increase of the length of the life span. This is 

 the essential physiological principle upon which the 

 cold storage and common storage of fruits depend. 



The most satisfactory temperature for storage pur- 

 poses is one which is low enough to reduce the life 

 activities to a minimum but not sufficiently low to 

 stop them entirely. It is important to remember that 

 a complete stoppage of the life functions of a fruit 

 organism means the death of it, and when this occurs, 

 the fruit soon thereafter becomes unfit for food. 



Much careful investigation remains to determine 

 the most satisfactory temperatures for various fruit 

 products. Many factors are involved. One of the 

 most important of these is the condition of the prod- 

 uct when it is placed in storage. Fruits of the same 

 kind and even of the same variety may have different 

 storage qualities and require different storage treat- 

 ments, depending upon the place where the fruit is 

 grown or its previous handling. Until these factors 

 are all known and controlled, it is unsafe to say that 

 any particular temperature is exactly correct for all 

 fruits. For this reason, it is difficult to limit storage 

 periods by law, because no arbitrary limit can be 

 satisfactory for all fruits. It would not be safe, for 

 example, to state that apples should not be kept longer 

 than a certain length of time. The same is true of 

 pears, but with this fruit the conditions are even more 

 extreme. Different varieties of apples and 

 pears may be held in storage different lengths 

 of time, and all warehousemen know by ex- 

 perience that the same varieties of fruits pro- 

 duced in different districts or in different sea- 

 sons have different storage qualities. 



The proper storage temperature for a fruit 

 should be the lowest possible that is. the 

 lowest temperature at which the fruit can be 

 held without actual injury. This is due to the 

 fact that when other conditions are satis- 

 factory, the lower it is possible to hold a given 

 product the longer it will remain in good con- 

 dition. This means, then, that the freezing 

 point of the fruit can be safely approached 

 under ordinary conditions. There are, natu- 

 rally, some important exceptions to this general 

 rule. 



As has been indicated above, different fruits have 

 different rates of life activities, and the more perish- 

 able fruits are those that have the most rapid rate. 

 For example, perishable fruits like berries, peaches, and 

 some varieties of grapes have very rapid life activities, 

 while the less perishable fruits such as apples, pears, 

 and the citrous fruits have a very low rate of life activi- 

 ties. This condition affects the storage period of a 

 R'ven fruit even under the most satisfactory condition, 

 is a well-known fact that the more perishable soft 



fruits cannot be held in storage for any great length 

 of time. The naturally short life can be lengthened 

 considerably but not to the same extent that the life 

 span of the hardier fruits can be lengthened. 



Berries of various kinds, cherries and cranberries, 

 may be hard frozen and held in such condition for 

 several months when the product is intended for use 

 in making sauce or pies. When the hard-frozen fruits 

 are removed from storage they must be used immedi- 

 ately, as they soon become soft and break down phys- 

 iologically. 



The most desirable cold-storage temperature for a 

 fruit, according to present knowledge of the subject, 

 is 32 F. for apples, pears, peaches, plums, strawberries, 

 raspberries, loganberries, blackberries (short time), 

 cherries, grapes, mangoes, celery, lettuce (short time). 

 An apparent exception is in the case of apples from the 

 middle coast section of California. The apples pro- 

 duced in this section require a somewhat higher stor- 

 age temperature, due to the fact that a peculiar discol- 

 oration of the flesh develops when this fruit is held 

 at the standard 32 temperature. This fruit is more 

 safely held at about 35. The varieties which are affected 

 by tnis trouble are principally Yellow Newtown, Mis- 

 souri Pippin, and, to a less extent, Yellow Bellnower. 

 This apparent storage weakness seems to be confined 

 to the mid-coastal district; apples from the mountains 

 and other districts of the Pacific coast seem to possess 

 normal storage qualities. 



For potatoes, 35 to 40 F., for citrous fruits, 45 

 to 50 F., are the most satisfactory temperatures. 

 Citrous fruits seem to be an exception to the general 

 rule that fruits of low life activities can be held at 

 temperatures near their freezing-point. Investigations 

 show that temperatures below 45 F. are injurious to 

 citrous fruits, except for a very short period. The low 

 temperature seems to affect the skin of the fruit, induc- 

 ing the deterioration by scald or stains and the develop- 

 ment of various fungous diseases. At a temperature of 

 45 to 50, or a common-storage temperature of 50 

 to 60, citrous fruits may be held for several months 

 without serious deterioration, provided means are 

 taken to prevent shriveling. Lemons are sometimes 

 held from four to six months at common-storage tem- 

 peratures without serious deterioration, when humidity 

 conditions are carefully attended to. 



The proper humidity of the air of storage rooms is 

 an important factor. Very little investigation of this 



OUTLET 



3703. Diagram showing proper method of ventilating a storage cellar. 



important problem has been undertaken and, conse- 

 quently, the fundamental factors governing the general 

 principles of humidity conditions in storage rooms have 

 not been definitely determined. Much shriveling of 

 fruits in cold storage has been due largely to excessive 

 evaporation on account of the free transpiration 

 activities of the fruits. Transpiration, or the giving-off 

 of moisture, occurs freely at high temperatures, less 

 freely at low temperatures. The moisture, however, is 

 being constantly given off even at low temperatures 



