34 BULLETIN 21i, U. S. DEPARTMENT OF AGRICULTURE. 



decay in the fruit in the top and bottom tiers. The lesser difference 

 at the beginning of the trip is partly accounted for by the fact that 

 the car was partially precooled before shipment. The data presented 

 in these curves emphasize strongly the necessity of loading the car in 

 such a way as to afford the freest possible circulation of cold air from 

 the bunkers to all portions of the car. 



It is not uncommon where salt has been added at each re-icing en 

 route to find spoilage both from freezing and from deterioration on 

 account of too high temperatures. In such cases the temperature at 

 the floor next to the iced bunkers becomes sufficiently low to cause the 

 freezing of some of the fruit on the floor in the ends of the car, while 

 at the top in the middle of the car the temperature is often so high 

 that the fruit is in an overripe condition. The temperature tests made 

 in fully loaded cars of berries in transit would indicate that it is not 

 ordinarily advisable to add salt in re-icing after the first 40 hours in 

 transit. During the first part of the journey and before shipment no 

 doubt the addition of a certain percentage of salt to the crashed ice 

 in the bunker greatly aids in obtaining quick cooling, but the addi- 

 tion of salt at each re-icing during a journey of over 40 hours may 

 result in considerable damage by freezing in certain portions of the 

 car. If there was some way of circulating the cold air throughout 

 the car so as to prevent the formation of cold pockets, salting 

 throughout at every re-icing would doubtless be highly beneficial. 

 Possibly the use of slats or racks on the floor would facilitate the free 

 circulation of cold air sufficiently to avoid the danger of freezing, 

 even though salting was practiced throughout en route. 



THE APPLICATION OF PRECOOLING. 



As a result of these investigations, every effort has been made by 

 the industry to procure proper handling, and a precooling plant has 

 been erected for cooling the fruit after loading it into the cars. 

 After observing the methods of operating a number of precooling 

 plants, one is impressed with the need of organizing or adjusting the 

 fruit picking and delivery so as to allow sufficient time to precool 

 the fruit successfully before it enters upon its journey to a distant 

 market. The most serious and common fault is that of allowing too 

 little time for precooling ; that is, attempting to do precooling in 

 less than half or quarter of the time actually necessary to accomplish 

 the desired results. Our experience has demonstrated beyond ques- 

 tion that the effective precooling of berries can not successfully be 

 accomplished in less than four or five hours. The precooling of a 

 car, fully loaded, for an hour or two hours accomplishes little in 

 the way of actual temperature reduction or in results from the stand- 

 point of the condition of the fruit on arrival, The investigations of 



