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UNITED STATEI 



DEPARTMENT of AGR JCttTURE 



DEPARTMENT CIRCULAR 350 



Washington, D. C. 



September, 1925 



AN IMPROVED TYPE OF PRESSURE TESTER 

 FOR THE DETERMINATION^ OF FRUIT 

 MATURITY 



J. R. MAGNESS" 



Physiologist 

 and 



GEORGE F. TAYLOR 



Associate Biophysicist 

 Office of Horticultural Investigations, Bureau of Plant Industry 



CONTENTS 



Page 



Introduction 1 



The pressure test as a measure of 



maturity 2 



Description of the apparatus 3 



Details of manufacture 3 



Essentials of manufacture 5 



Use of the pressure tester on apples. 5 



Page 



Effect of testing with and without 



peel removed 



Influence of rate of application of 



pressure on pressure-test results — 

 Range of pressures in apples as 



tested by this type of equipment — 



INTRODUCTION 



The determination of maturity in fruit is one of the most difficult 

 problems which the grower and handler must meet. The condition 

 of the fruit as to degree of maturity when it is removed from the 

 tree largely determines its dessert quality as well as its storage 

 or transportation possibilities. This factor of picking maturity is 

 of special importance with such fruits as peaches, plums, pears, and 

 apricots, which have a short shipping or storage life at best and vary 

 greatly in quality, depending upon the degree of maturity reached 

 when picked. Allowing the fruit to become too mature on the tree 

 results in a product which will not carry through to market, whereas 

 picking the fruit in a too immature condition results in an almost 

 inodible product. There is great need of definite picking standards 

 tor such fruits which will allow them to be left on the tree as long 



1 The writers wish to express their appreciation of assistance rendered by H. C. Diehl 

 and M. H. Haller, Junior Physiologists, in testing this instrument, and to R. E. Newton, 

 mechanic, for many valuable suggestions. A. F. Wahlstrom made the drawings. Others 

 of the Bureau of Plant Industry from time to time made helpful suggestions and 

 f ritieisms. 



42986—25 



