Cold-Storing Fruit Prior to Washing 



Since 1930 there has been a trend in the Pacific Northwest toward 

 holding unpacked apples in cold storage and thus extending the pack- 

 ing season over the fall and winter months. Various opinions have 

 been published as to the effect of washing and packing apples subse- 

 quent to refrigeration on the development of decay. Robinson and 

 Hartman (22) and Hartman, Robinson, and Zeller (18) recommended 

 washing immediately after picking as best for both residue removal 

 and decay control. Baker and Heald (2) reported that the cold storage 

 of Winesap and Delicious apples for 3 and 5 weeks, respectively, prior 

 to washing increased both the amount of lenticel infection and the 

 total blue mold decay. However, in these tests the fruit was dipped 

 in a spore suspension immediately after it was picked; it is possible 

 that the results would have been entirely different with naturally 

 contaminated fruit or with fruit inoculated at the time of packing. 

 In a later experiment the same investigators (3) compared the sus- 

 ceptibility of early and prime-maturity Delicious and Winesap apples 

 to lenticel infection when coated with a paste of decayed tissue at 

 harvesttime and after various periods of cold storage. In three of 

 the four lots used there was a marked reduction in the number of 

 lenticel infections when the inoculations were made after storage 

 periods of 60, 120, and 180 days as compared with fruit inoculated 

 immediately after harvest. There was some indication that suscep- 

 tibility to lenticel infection was increased by storage for 240 days. 



Evidence was not obtained in any of the 3 years (tables 4 and 5) 

 that holding apples loose in cold storage for 2, 6, or 10 weeks before 

 washing and packing definitely increases susceptibility to blue mold. 

 When fruit was stored for 6 weeks its resistance to infection was con- 

 sistently increased. In 1938 lenticel infections were decidedly fewer 

 on the fruit held in cold storage. In 1939 the number of lenticel 

 infections was reduced by 6- and 10-week delays but not by a 2-week 

 delay. The results in 1940 were inconsistent, but in general there 

 were slightly more lenticel infections and total decay in the fruit 

 immediately washed than in that stored before washing. 



Injury to the fruit from the washing process was invariably less 

 when the fruit was washed after various delays in cold storage than 

 when it was washed immediately after harvest (table 5). Except in 

 the case of the fruit held for 10 weeks in 1940, the reduction in the 

 amount of injury was directly related to the length of the storage period 

 before washing. 



The cold storage of apples in field boxes prior to washing has certain 

 accepted advantages, such as more rapid removal of field heat, pre- 

 vention of excessive accumulation of picked fruit in the orchard or 

 warehouse, and the distribution of packing over a longer period. 

 This practice permits a smaller investment in packing equipment, a 

 longer period of employment for the packing-house force, and an 

 opportunity to determine the marketing possibilities for a particular 

 season before additional investments are made. From the present 

 study it appears that storing the Delicious variety at 32° F. for periods 

 up to 10 weeks prior to packing has the additional advantage of 

 decreasing washing injury and susceptibility to blue mold infection. 



Against the advantages of cold storage in field boxes the packer 

 has to weigh the disadvantages of the increased cold-storage space 

 needed for unsorted, loose apples, the increased cost of handling loose 



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