20 



CIRCULAR 5 7 9, U. S. DEPARTMENT OF AGRICULTURE 



increased in firmness during ripening. In general, 18 pounds was 

 the lower limit for hard apples and the pressure test extended as 

 high as 24 on some apples. Firm apples ranged from 19 to 16 pounds, 

 firm ripe from 17 to 14, and ripe from 15 to 9. 



DISCUSSION 



As a result of these investigations it seemed possible to designate 

 a fairly definite range of pressure tests as representing each degree 

 of ripeness for the varieties studied. The pressure-test range for 

 each stage of ripeness held true with apples grown under varying 

 climatic conditions of 3 different years, at different picking maturi- 

 ties, and ripened at either high (70° F.) or low (36° and 32°) temper- 

 atures. Although there was an overlapping of the pressure-test 

 ranges for the several degrees of ripeness, this does not seem serious 

 in most cases and may result in part from inability properly to judge 

 the ripeness of some lots. On the other hand, as the fruit approached 



Figure 17. — Range of pressure tests, representing different stages of ripeness 



in 16 varieties of apples. 



the ripe condition it sometimes failed to continue softening and in 

 some instances increased in firmness, so its pressure test might be 

 higher when ripe than when firm ripe. Under such conditions the 

 pressure test would be of less value than tasting in determining the 

 ripeness of the fruit. The results indicate that the pressure tester 

 would be of much value in determining the ripeness of apples, and its 

 use would greatly reduce differences due to personal judgment. 



These results should be of value to cold-storage operators and to 

 fruit handlers in that they make it possible to translate pressure- 

 test readings into the more readily understood market terms de- 

 scribing ripeness in the case of the 16 varieties studied. These pres- 

 sure readings in turn represent, to some extent, the potential life of 

 sound fruit of a given variety. 



Figure 17, showing the range of pressure test considered to repre- 

 sent the different degrees of ripeness of the 16 varieties studied, is 



