io6 Journal of Agricultural Research voI.v.no.s 



work of the authors themselves. Briefly summarized, the results of 

 these investigations show that the principal changes which take place in 

 the apple during ripening are as follows : 



(i) A slight but continuous decrease in total acidity calculated as 

 malic acid. 



(2) A gradual decrease in sucrose. 



(3) A gradual increase at first, followed by a later slight decrease, in 

 invert sugar and total carbohydrates calculated as invert sugar. 



(4) The disappearance of starch early in the ripening process. 



ENZYMS IN APPLES 



The literature which is available to the writer contains very few 

 references to any investigations of the enzyms that are present in 

 apples. 



Lindet (9) found in the juice of apples a soluble ferment which causes 

 coloration of the tissues by the absorption of oxygen and the giving off 

 of carbon dioxid, which is inoperative when the juice has been boiled, 

 which may be precipitated from the juice by alcohol, and which oxidizes 

 pyrogallol to purpurogallin. He concluded that the coloration is due to 

 oxidation of tannin by a soluble ferment of the kind designated by 

 Bertrand as laccase (now called "oxidase"). 



Warcollier (12) is the only other author who reports work on enzyms 

 in apples. Although he was unable to find invertase in apple juice, he 

 beheves that it must be present in order to account for the apparent 

 inversion of sucrose during the ripening process. He suggests that the 

 enzym may have been retained by the apple marc and consequently may 

 have escaped his observation. 



The meagerness of the work which has been done along this line is 

 probably due to the fact that the flesh of the apple is not an important 

 element in the physiology of the plant's growth and has little scientific 

 interest to students of plant physiology or biochemistry. But its eco- 

 nomic importance and the desirabihty of knowledge concerning the 

 ripening process as a factor in the storage of perishable fruit products 

 are apparent and, in the writer's opinion, fully justify a thorough study 

 of the subject. The present paper does not constitute an exhaustive 

 report. It does not include, for example, a comparison of enzymic 

 activity of rapidly maturing varieties of apples as contrasted with those 

 which ripen more slowly and, hence, are better keepers. It is beUeved, 

 however, that the facts here presented will serve as a foundation for such 

 further work as may be found desirable. 



EXPERIMENTAL WORK 



The apples used in these investigations were secured from an orchardist 

 in the State of Washington and were of varieties known to be good 

 keepers — ^i. e., slow in ripening in storage. . 



