STUDIES ON ENZYME ACTION. 

 XIX. The Sucrolytic Actions of Bananas. 



By K. GEORGE FALK and GRACE McGUIRE. 

 {From the Harriman Research Laboratory, The Roosevelt Hospital, New York.) 



(Received for publication, February 3, 1921.) 

 INTRODUCTION. 



The change of starch into simpler carbohydrates such as glucose 

 sucrose, etc., or the reverse reaction, is a general phenomenon which 

 accompanies the growth and development (so called ripening) of 

 many edible fruits and also of a number of vegetables. For example, 

 the starch of apples and of bananas in the maturing of the fruit 

 becomes converted into simpler carbohydrates, while the sugars of 

 maize kernels and of peas are converted into starches.^ In the belief 

 that enzymes and enzyme actions play an important, if not a pre- 

 dominating, role in these chemical changes, a study was begun of the 

 enzymes which might be expected to be involved in these reactions. 

 The banana {Musa sapientum) was chosen as a typical example of a 

 fruit in which such changes occur because of the possibility of readily 

 obtaining large quantities of the unripe fruit, the rapidity with which 

 it can be made to ripen, the fact that it ripens when separated from 

 the growing plant, and the extensive change from starch into glucose, 

 invert sugar, and sucrose which accompanies the ripening. 



Previous Work. 



For the purpose in view, the chemical composition of the unripe 

 and ripe bananas is of interest. The results given by Gore^ are per- 

 haps the most satisfactory and may be quoted as follows: As a result 

 of ripening a number of bananas, a loss in weight of 3.88 per cent was 



^ Cf. Sherman, H. C, Chemistry of food and nutrition, New York, 1918, 12. 

 2 Gore, H. C, /. Agric. Research, 1914-15, iii, 187. 



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