EFFECTS OF FREEZES ON CITRUS IN CALIFORNIA 299 



CHANGES THAT TAKE PLACE IN FROZEN ORANGES AND 



LEMONS* 

 BY E. E. THOMAS, H. D. YOUNG, AND C. O. SMITH 



After the destruction of a large part of the citrus crop by the 

 freeze of January 6th and 7th, 1913, it was thought to be important 

 to make some studies of the physical and chemical changes that take 

 place in frozen oranges and lemons. The work was carried out at 

 the Citrus Experiment Station and was intended to determine as 

 definitely as possible, the nature and rate of changes that take place 

 in frozen fruit. While it is not impossible that the composition of 

 the ash or mineral elements may be affected, it was not considered 

 advisable to attempt to determine such changes in the time at the 

 disposal of the investigators and only the special points which could 

 most reasonably be expected to show variation were considered. The 

 following points were taken up in the investigation : 



The specific gravity of the fruits and of the juice. 



The average weight per fruit, of good and frozen fruit. 



The percentage and total amount of sugar (total sugar, sucrose 

 and reducing sugars) and acid. 



Sound fruit and badly frozen fruit of Washington navel oranges 

 and Eureka lemons were picked every four days following the freeze 

 for two and one-half months and these were weighed and analyzed. 

 They were compared with sound fruit and frozen fruit picked imme- 

 diately after the freeze and stored. 



Four different grades of fruit were examined. 



(a) Fruit known to be unfrozen, picked from trees whose blossoms 

 and small fruits showed no sign of frost injury. 



(ft) Fruit which was apparently unfrozen, judging from external 

 indications and picked from trees slightly injured by the freeze. 



(c) Fruit supposedly frozen, picked from same tree as sample (6). 



(d) Fruit picked from badly frozen trees about which there could 

 be no question of the frost injury. 



The badly frozen lemons were picked from the trees shown in fig- 

 ures 1 and 2. Oranges of this grade were obtained from large navel 

 trees in the same grove. 



* A summary of these investigations was first published by one of the authors, 

 H. D. Young, while he was employed in the Citrus Experiment Station, in a pape 

 entitled "The Composition of Frozen Oranges and Lemons." See Jour ] 

 Eng Chem., vol. 7 p. 1038, Dec., 1915. For further data on same subject see 

 article by H. S. Bailey and C. P. Wilson, "The Composition of Sound and Frozen 

 Lemons with Special Reference to the Effect of Slow Thawing on Frozen Lemons." 

 Jour. Ind. and Eng. Chem., vol. 8, p. 902, Oct., 1916. H. J. Webber. 



