10 CIRCULAR 447, U. S. DEPARTMENT OF AGRICULTURE 



SUMMARY 



Freezing or freezing injury does not always occur when fruit or 

 vegetable products are exposed to temperatures at or below their 

 actual freezing points. Under certain conditions many of these prod- 

 ucts can be undercooled; that is, cooled to a point below the true 

 freezing temperature of each and again warmed up without freezing 

 and without apparent injury. Certain products under certain condi- 

 tions may be actually frozen and afterwards thawed out without 

 apparent injury, while, on the other hand, some products are injured 

 by chilling if stored at temperatures well above their actual freezing 

 points. Evidence seems to show that different individuals of the same 

 variety and strain when grown under different conditions will have 

 somewhat different freezing points, and that there are also some vari- 

 ations in the freezing points of products of the same variety and from 

 the same lot. Sometimes this is due to different degrees of maturity. 



In view of these facts,- the freezing points given in this circular should 

 be considered only as danger points at or near which, either above or 

 below, there is a possibility of freezing injury if exposed for a sufficient 

 length of time. The temperatures given are those at which it is unsafe 

 to bold produce because of the danger of freezing. 



The freezing points of 34 commercial kinds of fruits, 45 of vege- 

 tables, 15 of cut flowers, 8 of bulbs, corms, or tubers, and 10 of plants 

 or florists' greens are given. Additional data are also given for a 

 number of different varieties of these kinds. 



