FREEZING TEMPERATURES 3 



fore, that temperatures just above the freezing point cannot be 

 regarded as safe for all types or varieties of fruits and vegetables. 

 It is also worthy of note that the freezing point of individuals of the 

 same variety grown under different conditions or even under the 

 same conditions may vary within a small range, as indicated in the 

 tables that follow. Attention is therefore called to the fact that the 

 freezing points given in the following tables should be considered as 

 danger points; that is, at or very near these temperatures there is 

 danger of injury by freezing if the exposure is for a sufficient length 

 of time. 



It has been found in some cases, as has been pointed out, that the 

 freezing point of a given variety is likely to vary slightly. These 

 variations, however, are probably of more importance in the study 

 of the exact causes and results of freezing injury than from the point 

 of view of the commercial cold storage and produce man, for a varia- 

 tion of a fraction of a degree hardly warrants any change in the 

 treatment of the product. 



The determinations of the freezing points of most of the commercial 

 varieties of fruits, vegetables, and other plant materials reported here 

 have been made by the Bureau of Plant Industry in connection with 

 its cold-storage investigations. 



Except where noted, the products reported upon were American 

 grown and harvested at the usual state of maturity for commercial 

 marketing. The method of determining freezing points has been 

 described elsewhere. 5 



FREEZING POINTS OF FRUITS 



Where several varieties of one kind of fruit were investigated the 

 results are given separately to allow comparisons between varieties. 

 The results are given in table 1. In table 2 these are summarized, 

 and in addition there are listed the results of freezing-point determina- 

 tions on a number of other fruits where only one representative variety 

 of a kind was studied. 



Apples 



Freezing-point determinations were made on a number of varieties 

 of summer or early apples and of fall and winter varieties, most of the 

 eastern-grown varieties being produced on the Arlington Experiment 

 Farm, Arlington, Va. The tabulated results by varieties (table 1) 

 show considerable varietal differences among both summer and 

 winter apples. The average of all summer varieties is practically the 

 same as that of winter varieties, the former being 28.4° whereas the 

 latter is 28.5° F. There is very little difference shown between the 

 freezing points of eastern-grown and western-grown fruit. 



5 Taylor, G. F. some improvements on the needle type thermocouple for low-temperature 

 work. Jour. Indus, and Engin. Chem. 12, 797-798, illus. 1920. 



Wright, R. C, and Harvey, R. B. the freezing point of potatoes as determined by the thermo- 

 electric method. U. S. Dept. Agr. Bui. 895, 7 pp., illus. 1921. 



Wright, R. C, and Taylor, G. F. See footnote 3. 



