io6 
Journal of Agricultural Research 
Vol. V, No. 3 
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: 
(1) 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 
believes 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 desirability 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 believed, 
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 M slow in ripening in storage. 
