FRUIT PRESSURE TESTERS 



Tests made through the skin of the fruit indicated that with the 

 needle-tvpe plunger ( 32 /ooo of an inch in diameter) the toughness of the 



;;.::j'^M\ 



skin was a disturbing factor, whereas with a plunger 

 diameter too great a 

 pressure (18 to 23 

 pounds) was required 

 to give accurate read- 

 ings. Blake, therefore, 

 preferred the plunger 

 % of an inch in diam- 

 eter, although he stated 

 that either size appar- 

 ently gives dependable 

 results. 



On prunes Hartman 



(33) used an Oregon- 

 type pressure tester 

 with a plunger % 6 of 

 an inch in diameter. 

 Hartman and Bullis 



(34) described a pres- 

 sure tester having a 

 plunger 2 millimeters 

 in diameter for use with 

 cherries. 



Culpepper and Ma- 

 goon (19) described a 

 needle- type pressure 

 tester with a No. 16 

 brass wire (%oo of an 

 inch in diameter) for 

 a plunger, reading from 

 to 400 grams. This 

 instrument was used to 

 test the toughness of 

 sweet corn kernels in 

 studies of maturity and 

 quality of different va- 

 rieties for canning. 

 The same type of in- 

 strument has been used 

 by Culpepper and his 

 associates in studies of 

 development and ma- 

 turity of a number of 

 fruits and vegetables, 

 such as peaches (17), 

 strawberries (18), snap 

 beans (15), asparagus 

 (20) , summer squash 

 (16), peas, and other 



of an inch in 



■j0!'^ 



Figure 2. — The Idaho pressure tester for stone 

 fruits (except peaches) and strawberries. 



products. For some of these purposes the instrument has been 

 modified by changing the strength of the spring and the range of the 

 scale and by using needles of different diameters. 



