2 Department Circular 350, U. S. Dept: of Agriculture 



as possible and at the same time assure their carrying through to 

 market in satisfactory condition. 



Of equally great importance, especially with such fruits as apples 

 and winter pears, which have a long storage or holding season, is the 

 determination of what may be termed "storage maturity." This 

 consists in the determination of the condition of the fruit between the 

 time of its removal from the tree and its ultimate consumption. Dur- 

 ing this period the fruit imdergoes a marked ripening process. The 

 texture of the flesh changes from firm or hard to soft and mealy, ac- 

 companied by changes in the chemical composition of the fruit and 

 oftentimes by changes in the color and appearance of the skin. 



In the case of apples and winter pears certain terms, such as 

 " hard," " firm," " ripe," " soft ripe," " dead ripe," or " overripe," 

 have been used to signify various stages of storage maturity. 

 Whether a certain lot of apples or pears falls into one class or the 

 other has been a matter of personal judgment. This has led to con- 

 fusion and to differences of opinion, which have often resulted in 

 rejections of shipments or adjustments of prices in the commercial 

 trade. These differences of opinion and the general uncertainty 

 regarding maturity- standards indicate the necessity of some test 

 for maturity in fruits aside from the unsupported judgment of an 

 individual. 



THE PRESSURE TEST AS A MEASURE OF MATURITY 



The most outstanding characteristic of the ripening process in 

 nearly all fruits is softening. Although this is associated with other 

 changes both chemical and physical in nature, the softening of the 

 fruit both on the tree and following picking appears to be one of the 

 most marked changes which occur during the ripening process, 

 particularly with deciduous-tree fruits. 



Pressure to determine the maturity of fruits by indentation of 

 the fruit with the thumb has probably been practiced as long as 

 fruits have been eaten by man. The use of a mechanical device to 

 measure the hardness of the fruit was first suggested by O. M. 

 Morris, of the Washington Agricultural Experiment Station. 

 Murneek ^ and other workers ^ of the Oregon Agricultural Experiment 

 Station have used such a test to determine the picking maturity of 

 pears and have developed a mechanical apparatus for determining the 

 pressure required to force a rounded plunger of definite dimensions 

 into the fruit for a certain distance. This apparatus has been used 

 to a limited extent for several years for determining the picking 

 maturity of pears in Oregon. The writer and others* have used a 

 slightly modified form of this apparatus in connection with apple- 

 storage studies and have found it to give an excellent index of the 

 actual condition of ripeness of the fruit at any time during the 

 storage period. It quickly became apparent, however, that if such 

 an apparatus is to come into general use for determining fruit 

 maturity, an equipment simple in design, easily portable, relatively 



2 Murneek, A. E. A new test for the maturity of the pear. Ore?. Sta. Bui. 186. 1921. 



'Hartraan. Ilenrv. Studies relating to the harvesting and storage of apples and pears. 

 Greg. Sta. Bui. 206. 1924. 



* Magness, J. R., and Burroughs, A. M. Storage investigations, 1921-22. The Marble 

 Laboratory (Inc.). 



and Diflil. II. C. Pliysiological studies on apples in storage. Journ. of Agr. 



Research, vol. 27, No. 1, G-347. 1924. 



