FREEZING INJURY OF FRUITS AND VEGETABLES 13 



occurs in old, unfrozen cabbage, but in the heads discussed here 

 there was no yellowing as in old cabbage. 



After 2 days at 18° F. unprotected heads of new cabbage were 

 found frozen solid. On thawing they were found to be worthless — 

 soft, water-soaked, and very leaky. 



For a discussion of the rate of cooling of three other lots of 

 cabbage see page 26. (For rate of cooling of one of these see 

 figure 3.) 



On the market, cabbage frozen severely enough to show injury 

 usually is worst affected in the stem and the heart leaves. These 

 parts are water-soaked and light brown. Severe or frequent 

 freezing causes the outer leaves to become paper thin. Slight 

 injury is often revealed by brown streaks in the stem (or heart) . 



Carrots 

 experimental observations 



Carrots were stored at 18° F. for 51 hours and then at 14° for 

 48 hours more. The container was a standard crate lined with 

 paper and with a pad under the lid. No extra paper was placed 

 over the outside. The carrots had been topped, leaving 2-inch 

 leafstalk stubs. (For data on the rate of cooling of carrots, see 

 also page 25 and figure 1.) On removal of the crate from the 

 freezing room all the easily accessible roots were found frozen and 

 numerous roots at the top were seen to be cracked lengthwise. 

 After 72 hours at 45° all the roots had thawed. Cracking was 

 fairly uniform throughout the crate, 48 percent being cracked and 

 52 percent not cracked. In many of the cracked roots the outer 

 layer, to a depth of about one-eighth inch, had separated from the 

 central cylinder and could easily be removed. There were no in- 

 ternal cracks extending outward from the center (radial crack- 

 ing) except in a few specimens that were spongy and leaky. Some 

 of the leafstalk stubs were plainly frozen to death (limp and 

 water-soaked) ; others appeared to be uninjured. After 72 hours 

 at 45° there was no increase in radial cracking and no softening. 



Another standard crate of carrots with the tops attached was 

 held in a 20° F. room for 48 hours. The crate was not lined but 

 was papered over the sides, ends, and bottom. On removal from 

 the freezing room the roots next to the sides, ends, and top of the 

 crate were found frozen. After 12 hours at 60° the only injury 

 that could be detected was in the limp, water-soaked tops that 

 were exposed along the edges of the lid. After 4 more days at 60 ° 

 the tops and roots at the top of the crate were wilted and the roots 

 had a poor flavor. Roots away from the outside of the crate 

 showed no injury and had a good flavor. No lengthwise cracking 

 was observed in any roots used in this test. 



MARKET OBSERVATIONS 



Freezing injury of carrots seen on the market consists of flabbi- 

 ness of roots, radial cracking of the central cylinder, and tangen- 

 tial cracking of the outer cortex. Water soaking is rarely seen. 



