2 MISC. PUBLICATION 3 4 0, U. S. DEPT. OF AGRICULTURE 



CRANBERRIES 



FREEZING, CHILLING, AND SMOTHERING INJURY 



Cranberries that have been frozen are tough and rubbery, lacking in 

 the characteristic high luster, and often somewhat sticky. Unlike 

 normal healthy berries, they are pink throughout rather than in the 

 epidermis alone for the reason that following freezing the pink color 

 diffuses from the epidermis into the whole interior structure of the 

 berry. This structure is not, however, destroyed; the outer wall, the 

 cross walls, and the tissues between them remain intact. 



With the exception of stickiness, the symptoms just described are 

 also found in cranberries that have been held at or close to 32° F. for 

 4 or 5 weeks but have not been frozen. The injury in this case is best 

 referred to as low-temperature injury or chilling. Such injury can be 

 avoided by holding the fruit at 36° to 40°. Temperatures higher 

 than 40° are undesirable because of danger of loss from decay, but 

 lower ones are not usually available in growers' warehouses, where 

 most of the storage life of the fruit is spent. The Early Black variety 

 seems to be more susceptible to low-temperature injury than the Searle 

 or the Late Howe. Low-temperature injury is not common on the 

 market because, under the present system of handling cranberries, 

 not many are held for long periods at temperatures sufficiently low to 

 cause it. 



The term "smothering injury" is used to refer to a condition like 

 that just described, but which is thought to be caused by holding 

 cranberries in containers or in storage space where carbon dioxide 

 accumulates and the oxygen supply is low. Formerly it was some- 

 times found in the tight barrels used for marketing cranberries. At 

 the present time practically all of the crop is handled in quarter- 

 barrel ventilated boxes, which furnish conditions definitely unfavora- 

 ble to smothering. However, the injury is still found at times in 

 growers' warehouses, especially if they are overloaded and are not 

 well ventilated. Such warehouses are really only air-cooled storages, 

 so that there is no likelihood that the condition found in them is 

 in reality low-temperature injury except possibly in poorly managed 

 or poorly insulated warehouses late in the storage season. 



In experimental lots of cranberries showing low-temperature 

 break-down, the percentage of berries affected has been high, and 

 there has been very little fungus rot. This is in contrast to the 

 condition observed in connection with so-called smothering, which 

 usually affects a smaller proportion of the berries and is accompanied 

 by more than the usual amount of rot (34, 35). 2 



Smothering injury is usually found at or near the center of the 

 container, whereas freezing is more likely to occur around the out- 

 side. If temperatures in storage have been such as to cause chilling 

 injury, this condition can be expected to occur rather generally 

 throughout the container. 



FUNGUS ROTS 



The rots of cranberries are numerous, but not easily distinguished 

 from each other on casual examination even by a specialist. They 

 differ from three other conditions previously described (p. 2) that 

 may affect cranberries; namely, freezing injury, chilling, and smoth- 



2 Italic numbers in parentheses refer to Literature Cited, p. 24. 



