Oct. i8, 1915 
Enzyms of Apples 
hi 
occurrence, there being always the possibility that observed changes in 
the nature of the sugars present in successive samples may be due to the 
action of organic acids during the preparation of the samples for analysis. 
TANNASE 
Determinations of the tannin content of each of the four varieties of 
apples which were being used by Proctor's modification of Lowenthal’s 
method 1 showed that the flesh of the apples contained the following per¬ 
centages of tannin: Rome Beauty, 0.208; Arkansas Black, 0.192 ; Yellow 
Newtown Pippin, 0.208; King David, 0.132. 
It seemed advisable to ascertain, therefore, whether any tannin¬ 
hydrolyzing enzym was present in these tissues. Accordingly, a quantity 
of pulp from each variety was ground with quartz sand and the juice 
expressed. One portion of the juice from each variety was boiled and 
another left unboiled. Aliquots of the boiled and unboiled juice were 
placed in each of two test tubes, to one of which 2 c. c. of a 10 per cent 
solution of Merck’s tannic acid was added, in order to insure sufficient 
excess of substrate material. The four sets of four tubes each were placed 
in an incubator at 40° C. for 24 hours. At the end of this time a few drops 
of a 10 per cent solution of ferric chlorid were added to each test tube 
and the intensity of color developed in the tubes containing check boiled 
and unboiled juices was compared. In no case could the slightest 
difference in intensity of color be observed, from which it was concluded 
that the juices contained no tannase. 
EMULSIN 
Glucoside-splitting enzyms were tested for in boiled and unboiled 
juices prepared from each of the four varieties of apples by digesting 
aliquots of these juices with 2 c. c. of a 1 per cent solution of amygdalinfor 
24 hours at 40° C. In no case was any odor of benzaldehyde perceptible 
at the end of this time, while check tubes to which emulsin was added 
gave a pronounced odor after only 10 minutes’ contact with the amyg- 
dalin used. Hence, it was concluded that the apple flesh contains no 
enzym of the emulsin type. 
ESTERASES 
One of the noticeable changes in an apple during the ripening period 
is the development of its characteristic odor and flavor, due chiefly to 
the ester ethyl malonate. Such esters are usually accompanied in nature 
by a corresponding esterase; hence, it seemed advisable to test the flesh 
of the apples for an esterase which would hydrolyze ethyl malonate. 
Accordingly, apple juice was obtained by the quartz-sand method and 
a series of test tubes prepared with the following contents: (1) 5 c.c. 
of apple juice, 5 c. c. of ethyl malonate, and 10 c. c. of distilled water; (2) 
5 c. c. of apple juice which had been previously boiled for 10 minutes, 
1 Wiley, H. W., et al. Official and provisional methods of analysis, Association of Official Agricultural 
Ckemists. U. S. Dept. Agr. Bur, Chem. Bui. 107 (rev.), 272 p. 1908. See p. 150. 
