CHEMICAL CHANGES IN APPLES DURING STORAGE 87 



COMPOSITION OF HAND-PICKED AND WINDFALL APPLES, 1898. 



At temperatures of 60 degrees to So degrees Fahr. apples 

 change rapidly, and so far as this change is due to the forma- 

 tion of invert sugar, the temperature is the most important 

 factor in its control. Cane sugar is changed to invert sugar by 

 a ferment or enzyme called invertase,* which exists in the cells 

 of many species of plants, and especially the yeasts. It has 

 been found in several fruits and probably exists in the apple. 

 By the transformation of cane sugar to invert sugar, a sugar is 

 formed which is capable of further decomposition into simpler 

 compounds, the best known change being the one into alcohol 

 and carbon dioxide, occurring in fruit juices, of which cider 

 and wine are made. 



O'Sullivany has shown that the enzyme invertase is active 

 but slow at 32 degrees Fahr., while at 70 degrees its effect on 

 the inversion of sugar is quadrupled, in fact, its activity doubles 

 for every increase of rS degrees Fahr. 



It is evident, therefore, that the lowest possible temperature 

 at which apples may be kept without freezing, is necessary to 

 most effectively retard changes in the fruit, which are entirely 

 independent of the attacks of fungi ; but are the results of 

 activity within the cells of the apple itself. 



*" Fermentation," Reynolds Green, Chap. 8. 

 t Jour. Chem. Sec, 57, 834. 



