STORAGE 



3247 



storage are frequently responsible for untimely deterio- 

 ration, and the practice should be discouraged; but so 

 far as fruits and vegetables are concerned, it is perfectly 

 safe to state that no injurious effects have ever followed 

 the use of these cold-stored foods. The evidences of 

 deterioration are plainly visible in fruits and vegetables 

 and there are no hidden germs or ptomaines. No one 

 is likely to be deceived into eating a deteriorated fruit 

 or vegetable. 



The agitation against cold-stored food products has 

 resulted in a demand for legal regulation of the storage 

 business. Several states have passed laws prescribing 

 certain conditions which must be met. Attempts have 

 been made to obtain federal regulation, and no doubt 

 federal laws concerning the cold storage of foods will 

 eventually be enacted. The state laws now in effect 

 and the proposed federal legislation place arbitrary 

 limits upon the time the products may be held; pro- 

 vision is also made regarding the marking of the prod- 

 ucts, and the inspection of the goods from time to time 

 is provided. Legal regulation of this business is desir- 

 able and wise, but it is not wise to present arbitrary 

 obstacles to the development of refrigeration. It is 

 questionable whether the adoption oT an arbitrary 

 length of time for holding all products is wise or safe. 

 Not only does the length of time vary for different 

 classes of goods, but within the same class the con- 

 dition of the product at the time it is placed in storage 

 or its treatment previous to storage very materially 

 influences the time the product may be held in whole- 

 some condition. Thus, not all apples of a given variety 

 may be held the same length of time. The length of 

 the period of successful storage will depend upon the 

 condition of the fruit, its stage of maturity, the care 

 with which it has been handled, and also the promptness 

 with which it has been copied. The same principle 

 holds true for all other fruit and vegetable products. 

 It would seem, therefore, that some provision for the 

 inspection of food products to determine their fitness 

 for storage would be wise and would result in prevent- 

 ing many losses now sustained through the storage of 

 unfit goods. So far, none of the laws passed or proposed 

 makes this provision. 



This argument is not offered to defend the cause of 

 cold-storage warehousemen. They have not been 

 entirely free from blame in the past. The possibilities 

 and the advantages of cold storage should be fully 

 appreciated by consumers and producers alike. The 

 necessity for refrigeration in horticultural industries 

 will undoubtedly become more and more urgent, and 

 the use of this important adjunct to modern fruit-grow- 

 ing is bound to extend its scope and receive wider 

 application in the future. 



Cold storage is a modern economic necessity. 

 Through this system of food conservation, the exten- 

 sion of markets and the territory over which different 

 commodities may be distributed are very materially 

 increased. In the use of cold storage or refrigeration, 

 the first establishments depended on ice for the refrig- 

 erating medium. In the earliest plants natural ice was 

 used. This was gathered or "harvested" during the 

 winter and used during the spring and summer months. 

 There is a very large quantity of natural ice used under 

 modern conditions, but the manufacture of ice is 

 increasing and the use of "artificial"' ice is likewise 

 extending, even in districts where natural ice may be 

 obtained without difficulty. 



Systems of refrigeration . 



In modern cold-storage plants two systems of refrig- 

 eration are used: (1) ice refrigeration, and (2) mechan- 

 ical refrigeration. There are several methods of apply- 

 ing each system. In the use of the first, ice alone may 

 be the refrigerant, or a mixture of ice and salt may be 

 used to obtain lower temperatures than are possible 

 from ice alone. In the application of the ice-and-salt 



refrigerant, several systems may be used, as will be 

 explained later. The ice used may be manufactured or 

 natural, depending on the relative cost. 



In the mechanically refrigerated plant, the refriger- 

 ation is secured directly without first producing ice. 

 It is apparent that the direct application of the refriger- 

 ation results in a very material saving in both time and 

 energy. In this way, the cumbersome method of first 

 manufacturing the ice and the consequent inconven- 

 ience in handling it are avoided. 



There are two kinds or styles of cold-storage plants 

 the general warehouse, provided with cold-storage 

 equipment for handling all classes of commodities; 

 and the storage plant constructed specially for the 

 storage of a particular class of commodities fruit or 

 dairy products for example. It is evident that the large 

 general warehouse may have a very great advantage 

 in economy of operation. The general warehouse 

 handles a mixed business which often results in a more 

 economical distribution of overhead operating expenses 

 than is possible when the entire burden of expense 

 must be borne by a single commodity or single class 

 of commodities. It is easy to see that the greatest 

 efficiency and economy of operation occur where prac- 

 tically the entire capacity of the plant can be utilized 

 during the year. This is hardly feasible with fruits, 

 with the possible exception of apples which are now 

 held largely during the greater part of the year. But 

 even in the case of apples, there cannot be a full use of 

 the equipment continuously, as the withdrawals will be 

 gradual throughout the season. Nevertheless, the con- 

 struction and operation of cold-storage plants for apples 

 or other fruits is constantly increasing. These plants 

 mav be owned by special corporations or may be built 

 and operated by growers' organizations or by growers 

 who have sufficient acreage to warrant the extra pro- 

 vision of storage facilities. In some instances the owner- 

 ship or control of cold-storage facilities has rendered 

 fruit-growers independent of buyers' or speculators' 

 manipulations of prices or marketing facilities. 



Mechanical refrigeration depends on the compres- 

 sion of a gas or vapor. The compression exerted heats 

 and, in some instances, liquefies the gas. The heat is 

 absorbed by means of cooling water, and when the 

 gas is allowed to expand, an equal number of heat 

 units is absorbed from the surrounding medium. This, 

 briefly, is the general principle upon which depends 

 the operation of refrigeration machines. The gases 

 used may be air, ammonia, sulfur dioxide or carbon 

 dioxide, commonly known as carbonic-acid gas. In the 

 cases of air machines, the air is simply compressed 

 under very heavy pressure and cooled by means of 

 water. There is no liquefaction of the air attempted in 

 the case of these machines. The advantages of the air- 

 compressors are that they are comparatively easy to 

 manipulate and there are no injurious effects in case 

 of leakage from the compressed vapor. These machines 

 are used to a great extent on shipboard, and in England 

 to a much greater extent than in the United States. 

 Improvements in the construction of air-compressing 

 machines are resulting in their increased use. The dis- 

 advantage of the air-refrigerating machines is that 

 they are relatively inefficient for low temperatures. 

 There being no liquefaction of the gas, the advantage 

 of the latent heat due to the change of state is absent, 

 and consequently there is a loss of efficiency to the 

 extent of the latent heat necessary, first, to change the 

 gas to the liquid and then back from the liquid to the 

 gaseous state. 



In the machines which utilize a liquefiable gas, that 

 is, a gas which may be liquefied at comparatively high 

 temperatures, the latent heat due to the change of 

 state adds greatly to the efficiency of the machines, and 

 consequently, much lower temperatures can be secured 

 for a given amount of power. One of the essential 

 qualities of the gas which may be used for this purpose 



