80 MASS. EXPERIMENT STATION BULLETIN 198. 



by cranberries during storage, and this loss is greater at the higher tem- 

 peratures, while the destruction is further accelerated by a lack of air. 

 The total acidity changes were very httle, hence on account of its high 

 proportion in cranberries they do not lose flavor on long keeping as notice- 

 ably as some other fruits. 



Respiration of Cranberries. 



The percentage changes in the composition of fruits produced by differ- 

 ent storage temperatures throw Uttle light on the real rate of change at a 

 given temperature. A simple method of estimating the rate of chemical 

 change in fruit at any given temperature is to determine the amount of 

 carbon dioxide exhaled by a definite weight of the fruit in an hour. The 

 carbon dioxide is produced by respiration of the fruit, just as it is pro- 

 duced in animals by the same action. The oxygen of the air penetrates 

 the cells ^ of the fruit and unites with some of the matter in the cells, ap- 

 parently the sugar, and forms carbon dioxide and water which are exhaled. 

 There is no appearance of rhythmical action, as in the breathing of animals, 

 but the exhalation of the carbon dioxide and water can be readily deter- 

 mined by chemical means. 



Respiration experiments with several kinds of fruits ^ have been re- 

 ported, and it has been shown that respiration varies noticeably with 

 changes in the temperature of the fruit. 



Respiration experiments mth cranberries were carried out during two 

 seasons, 1917-18 and 1918-19. One kilogram of cranberries was used in 

 nearly every case, and whenever possible for convenience in calculation. 

 The berries were carefully hand-sorted before weigliing the desired quan- 

 tity, in order to avoid any berries which had begun to rot. It was imprac- 

 ticable to hold the cranberries closely to a given degree of temperature 

 during a run, and it was found necessary to maintain them for several 

 hours before a run as closely as possible to the temperature desired to be 

 tried in the respiration chamber, because the internal temperature of the 

 berries was slow to adjust itself to that of the chamber if they were far 

 apart, and the exhalation of carbon dioxide might be too high or too low 

 acco^dinglJ^ By close attention to details and to the thermometer, the 

 range of temperature during any one run was kept within one or two 

 degrees. Several different temperatures were tried, from about 2° to 25° 

 C. (35° to 77° F.). The lowest temperatures were obtained by setting 

 the respiration chamber inside a small tank which could be packed with 

 snow. Temperatures around 10° C. were obtained at times by surround- 



1 The authors' attention has been called by Dr. Stevens to a little-known paper by Winton 

 (Conn. Agr. Expt. Sta. Ann. Kept. 1902, p. 288), in which is noted the absence of stomata in the 

 epidermis of the cranberry. Bergman, while studying the cranberry, rediscovered this fact, 

 and a paper by him is in press in the bulletin of the Torrey Botanical Club. 



2 Morse, Jour. Am. Chem. Soc. 30 (1908), pp. 876-881; N. H. Agr. Expt. Sta. Bui. No. 135 

 (1908). Gore, U. S. Dept. Agr., Bur. of Chem. Bui. No. 142 (1911). Hill, Cornell Univ. Expt. 

 Sta. Bui. No. 330 (1913). 



