A PHYSIOLOGICAL STUDY OF GRAPEFRUIT RIPENING 



AND STORAGE ' 



By IvON A. Hawkins 



Plant Physiologist, Office of Horticultural and Pomological Investigations, Bureau of 

 Plant Industry, United States Department of Agriculture 



In an earlier investigation (7) ^ the changes in Florida-grown grape- 

 fruit during storage were studied, particular attention being paid to the 

 sugar and acid content of the pulp or edible portion of the fruit as influ- 

 enced by some six different storage temperatures. It was found that the 

 acid content decreased in cold storage while the total sugar content re- 

 mained about the same. The percentage of cane sugar decreased and 

 the reducing sugar content increased. At the higher temperatures, 

 common storage (about 55° to 60°, 70°, and 86° F.) there was in some 

 cases apparently an increase in acidity and a reduction in the amount of 

 sugar, especially in fruit stored for long periods. The shrinkage, which 

 was very marked in the ventilated packages at these high temperatures, 

 made the obtaining of definite evidence on this point impossible. 



The investigation described in the present paper is concerned with the 

 acid and sugar changes in the fruit on the tree as well as with the changes 

 which take place, both in warm storage and in cold storage, in fruit picked 

 at monthly intervals. The control of the pitting which occurs commonly 

 on grapefruit in cold storage is given some attention. 



PLAN OF THE EXPERIMENTS 



" Common Florida " ^ fruit from two trees was picked at monthly inter- 

 vals for four months, beginnmg July 27, making five different picks. At 

 the last three pickings fruit was also harvested from two additional trees 

 in the same grove. The fruit was expressed to Washington and sampled 

 on arrival. Part of the fruit was placed in warm storage at about 

 70° F. and part in cold storage at 32°. Analyses were made of the fruit 

 stored in the warm storage each month for two months and on fruit from 

 the last three pickings stored in cold storage, after it had been in storage 

 four months. By this plan it was possible to obtain data on the changes 

 in the fruit on the tree from a month or so before the fruit was in con- 

 dition to pick for market until the last of the season, and to compare the 

 changes which took place in cold storage in fruit picked from the same 

 trees at different times of the season. 



1 This paper gives the results of a portion of the work carried on under the project " Factors affecting the 

 storage life of fruits." 



2 Reference is made by number (italic) to " Literature cited," p. 278-279. 



' The writer's thanks are due Mr. W. J. Krome for the picking and shipping of all the " Common Florida" 

 fruits used in these exijeriments. 



Joimial of Agricultural Research, Vol. XXII, No. s 



Washington, D. C. Oct. 29, 192 1 



aag Key No. 0-251 



(263) 



