6 Department Circular 350, U. S. Dept. of Agriculture 



ticularly applicable to this fruit, though they may be equally per- 

 tinent to the testing of others. 



The use of the apparatus is illustrated in Figure 3. The skin of 

 the apple to be tested is first removed by slicing off an area one-half 

 to three-quarters of an inch in diameter, because the sldn tends to 

 mask the actual condition of the flesh of the apple, as will be shown 

 later. The fruit is then placed against a wall or any convenient sur- 

 face, and the end of the plunger is directed squarely against the cut 

 surface. Tlie opposite end of the apparatus rests against the hand, 

 as illustrated, and pressure is applied until the plunger penetrates 

 the fruit sufficiently to push the collar (A) up against the disk (F). 

 This completes the circuit, lighting the flashlight. The number of 

 pounds indicated on the scale when the light flashes is recorded. 



The dimensions of the plunger here shown have been found very 

 satisfactory for the testing of apples, particularly for determining 

 the storage maturity of the fruit. They closely approximate those 

 of the Oregon Agricultural Experiment Station tester. For certain 

 fruits plungers of smaller cross section or depth of penetration may 



■^HBj^H 



r-#=^^^^^^^pf %':■•- •■'■ ■■ .:- 



l^U 



^^^.i^^^jiT^ 





■ .^^ JHe' iji # ' ' 



•^.^ / '*^^l 



Fig. 3. — Pressure tester, illustrating the method of its use with an apple 



be desirable. If so, they can be developed readily on the same gen- 

 eral principle, or plunger tips of varying sizes can be used with the 

 instrument here described. 



EFFECT OF TESTING WITH AND WITHOUT PEEL REMOVED 



In Table 1 are reported certain data from specific tests which 

 serve to emphasize the necessity of testing apples with the peel 

 removed. Tests made at the time of picking several varieties with 

 and without the peel removed are recorded, together with tests of 

 similar fruit when in prime eating condition. All of the data here 

 reported are averages of the determinations of 25 apples, and the 

 tests when the fruit was in prime eating condition were made on 

 fruit of the same pick and from the same trees as that made at the 

 time of picking. 



A comparison of the difference between the tests made with ,and 

 without the peel removed shows that, with the exception of Mcintosh, 

 every variety showed a greater difference due to the skin when the 

 fruit was soft or in prime eating condition than at the time of pick- 

 ing. In most cases the difference in the soft fruit, depending on 

 whether or not the peel was removed, was practically double that 

 found in fruit at picking time, showing that the skin tends to mask 



