EASTERN-GROWN APPLES 21 



t 



presented for easy reference. The ranges for hard do not necessarily 

 indicate the upper limits for this stage of ripeness. Although fairly 

 early pickings were generally made, the pressure-test distinction 

 between immature apples of a variety and mature hard apples of the 

 variety was not determined. Previous work 6 has shown that the 

 pressure test is not entirely reliable for distinguishing between im- 

 mature' and mature apples. It is possible, therefore, that the range 

 for hard may extend higher than indicated. Although the apples 

 used in these investigations were considered mature, it is possible 

 that under different growing conditions apples testing in the hard 

 range of firmness may be immature. 



In using figure 17 with a given lot of apples it is necessary to con- 

 sider the range of firmness within the lot rather than just the aver- 

 age pressure test for the lot. For example, a lot of Ben Davis 

 apples might have an average pressure test of 15.2 pounds but with 

 extremes of 14 to 16.5. Thus, although the average is in the firm 

 range, as shown in figure 17, some of the apples would fall in the 

 firm-ripe range and some would be intermediate in ripeness. Such 

 a lot would be classed as firm to firm ripe, possibly mostly firm. 



A pressure-test range for overripe apples is not given in figure 17. 

 Apples were not generally considered overripe unless they showed 

 signs of break-down, and the pressure test would be of little value in 

 indicating this, as many apples showed break-down although in the 

 upper limits of the ripe stage in firmness. 



Pressure testers sometimes get out of adjustment and may register 

 incorrectly. It is important that any tester used to determine ma- 

 turity of apples be standardized or checked at intervals to be sure that 

 it registers correctly. 



The type of tester having a slide indicator can readily be checked 

 by forcing the plunger of the tester against the platform of a platform 

 scale until a given weight is registered and checking this against 

 the reading on the tester. Theoretically, the weight of the plunger 

 rod should be deducted from the scale reading. However, this is not 

 done by the manufacturers in the original setting of the instruments 

 and is of no practical significance. 



SUMMARY AND CONCLUSIONS 



One to three pickings of 16 varieties of apples were made during 

 three seasons (1935-37) and stored at 70°, 36°, and 32° F. The firm- 

 ness of the apples was determined by means of a pressure tester at the 

 time of picking and at intervals during ripening at the different tem- 

 peratures. At the time the firmness was determined the stage of ripe- 

 ness (as defined in the United States Apples Standards) was 

 estimated. 



As the apples ripened they generally became softer, and it was found 

 that each stage of ripeness was represented by a fairly definite range of 

 firmness. The pressure-test range for each degree of ripeness varied 

 somewhat among the different varieties. It is shown for each variety 

 by means of graphs. 



The use of the pressure tester was found to be a valuable supple- 

 mentary method to determine more accurately the stage of ripeness of 

 apples. 



6 Magness, J. R., et al. See footnote 5. 



