10 CIRCULAR 713, U. S. DEPARTMENT OF AGRICULTURE 



neath bruises produced by the pressure of one apple against 

 another. 



Bruises like those just described can be produced by subjecting 

 apples to a jolting similar to that received while they are in transit 

 by rail. Glassy, water-soaked bruises are not necessarily a sign of 

 freezing injury; neither are wedge-shaped injured areas that ex- 

 tend to the core nor brown bruised spots under the skin, in which 

 browning of the water-conducting bundles has occurred. All of 

 these can be produced by the jolting and pressure that apples are 

 subjected to while in transit in railroad cars. 



EFFECT OF FREEZING AND THAWING 



It is generally believed that frozen apples are injured less by 

 gradual than by rapid thawing. Investigation has shown, how- 

 ever, (1) that apples frozen rapidly show an equal amount of in- 

 jury when thawed at 32° and 72° F. and (2) that slowly frozen 

 apples show more discoloration when thawed slowly (at 32°) than 

 when thawed rapidly (at 50° or higher) . 



Frozen apples are often dry and mealy, probably because of loss 

 of water through evaporation from the injured tissues. The de- 

 gree of mealiness increases with the amount of freezing but is not 

 entirely absent even when freezing is only slight. The flesh some- 

 times appears flaky or corky and always lacks the normal crisp- 

 ness ; in severely frozen specimens it collapses and becomes viscid, 

 soft, and mushy. 



Apples frozen but not frozen to death may thaw out with no 

 apparent aftereffect except a slight softening of the flesh. This 

 softening, however, means that their prospective storage life has 

 been shortened. The amount of the reduction will depend on the 

 variety, the degree of maturity of the fruit when frozen, and the 

 severity of the freezing. There is no doubt that apples that have 

 been frozen solid throughout, even though for only a short time, 

 will not hold up so well in storage, or for so long a time, as similar 

 apples from the same orchard or the same storage lot or shipment 

 that have not been frozen. 



Apples should not be handled while frozen, because of the 

 danger of serious damage from bruising. Bruises produced in this 

 way frequently extend deep into the fruit, and the affected flesh is 

 usually brown, soft, and somewhat watery. 



FREEZING INJURY AND INTERNAL BREAK-DOWN 



During January or even earlier and through the remainder of 

 the storage season, it may sometimes be difficult to distinguish be- 

 tween freezing injury and internal break-down due to overripe- 

 ness. The difficulty will be greatest when there is no evidence of 

 freezing in transit. Internal break-down may be followed by 

 browning, but the color change, unlike that which often follows 

 freezing injury, does not begin in the main water-conducting 

 bundles. Instead, it may begin at any place in the flesh and usually 

 does begin at many places. In cross section, fruits affected with 

 internal break-down often show the following symptoms: An 

 outer shell of healthy flesh about a quarter of an inch thick sur- 



