Journal of Agricultural Research 



Vol .V, No. 3 



Table III. — Results of tests for invertase in the flesh of apples 



Reducing sugars. 



Variety and material. 



Yellow Newtown Pippin: 



Decanted juice 



Decanted juice (boiled) 



Decanted juice (neutralized) 

 Control (water only) 



Rome Beauty: 



Decanted ^uice 



Decanted juice (boiled) 



Decanted juice (neutralized) 

 Control 



G^n. 



o. 0113 



. 0217 

 .0103 



None. 



.0103 

 . 0207 

 .0113 

 None. 



These results being so contrary to what was expected, it was thought 

 best to use material prepared for examination in several other ways in 

 testing for invertase. Accordingly, a water extract was made of some 

 acetone-dried powder from Rome Beauty apples, another sample of the 

 same apples was ground with quartz sand and its juice expressed, and 

 finally a sample of the Gore's concentrated apple juice was diluted to 

 about the same concentration as normal apple juice. Each of these 

 materials was then incubated with sugar solution in the usual way, using 

 unboiled and boiled samples of both the acid and neutralized juice in each 

 extract. The reducing sugars found in the digested mixture from the 

 unboiled or "active" extract and from an equal aliquot of boiled extract 

 are given in Table IV. 



Table IV. — Tests for invertase in various preparations from the flesh of apples 



The results shown in Tables III and IV indicate the absence of any 

 invertase in apple flesh and confirm the observations of WarcolUer (12), 

 referred to above. It appears, therefore, that changes during ripening 

 which result in the inversion of sucrose, if they actually occur, must be due 

 to som.e other cause than the presence of invertase in the apple tissues. 

 The fact that some investigators have not been able to find evidence of 

 this inversion of sucrose during ripening casts some doubt upon its actual 



