FREEZING INJURY OF FRUITS AND VEGETABLES 9 



and have a superficial diameter about equal to their depth. In vir- 

 tually all cases these sunken spots develop at places that were 

 bruised while the apples were still frozen. 



When freezing occurs the cells of the vascular, or water-conduct- 

 ing, system are usually the first to be affected, especially if the 

 freezing takes place rapidly ; and they may be the only ones so af- 

 fected. In cross section this injury is shown by a brown discolora- 

 tion of the 10 large main water-conducting bundles, the color being 

 visible evidence that the cells have been frozen to death. Similar 

 browning may occur in the smaller strands through the flesh and 

 in the core tissue ; it is frequently restricted to one side of the apple 

 because of lower temperature on that side. In more extreme cases 

 all the tissues may be affected ; the flesh then shows a solid color 

 throughout, which varies from bright golden brown to darker 

 brown or almost black, depending on the variety of apple and the 

 severity and freshness of the freezing injury. These browned 

 areas in whatever tissue found usually have a water-soaked 

 appearance and in milder injury are translucent. 



It should be remembered, however, that during a short exposure 

 to an air temperature several degrees below freezing considerable 

 ice may form within the tissues and yet produce little or no effect 

 that could be diagnosed as freezing injury. 



FREEZING INJURY AND TRANSIT BRUISING 



Apples that have been both bruised and frozen while in transit 

 by rail frequently show flattened areas 1% to 2 inches in diameter 

 that are somewhat sunken and soft toward the center and have a 

 dull-brown or slate color over most or all of the surface. 



Another kind of bruising occurs in boxed apples in transit. This 

 injury is usually found only in apples at the lower side of the bot- 

 tom layer of boxes in the car and for this reason is frequently at- 

 tributed to freezing. It is more common during winter than dur- 

 ing fall and spring, but nevertheless it has been found in boxed 

 apples shipped in the fall before freezing weather has occurred in 

 the producing districts or anywhere along the route taken by the 

 shipment. The injury has also been found so late in the spring 

 that there was no possibility of the fruit having been exposed to 

 freezing weather in transit. 



This transit bruising is characterized by flat, bruised areas on 

 the sides of the apples that were in contact with the lower side of 

 the box as the latter lay in the car. These areas have a water- 

 soaked, darkened appearance, are generally rather firm, and may 

 be an inch or more in diameter. Occasionally the skin covering 

 them is discolored in spots or streaks. In cross section there is 

 usually a water-soaked, glassy, wedge-shaped area extending from 

 the skin toward the center of the apple. It may be shallow or may 

 extend quite to the core. In some instances the inner edge of this 

 area appears as a fairly smooth curve, convex toward the core ; in 

 others it is broken by strands or rays having the water-soaked ap- 

 pearance just mentioned and extending radially for as much as 

 three-quarters of an inch beyond the main affected area. Small, 

 water-soaked patches or streaks are sometimes seen also under- 



