598 VEGETABLE ENZYMES. XIX 



, Enzyme Tests with Unripe Bananas. 



The enzyme tests with unripe bananas can be summarized briefly; 

 since (a) the general relations found were the same as with ripe 

 bananas, except that {h) greater enzyme actions were obtained with 

 ripe banana preparations than with unripe, and (c) the nature and 

 properties of the unripe banana rendered working with it more diflEi- 

 cult and less satisfactory. 



The methods of studying the unripe banana pulp were as follows: 



1. Pulp extracted with equal weight of water, filtered through 

 muslin. Filtrate and residue (to which an equal quantity of water 

 had been added) tested at different hydrogen ion concentrations in 

 1 per cent sucrose (also more concentrated) and starch solutions for 

 18 hours at 35°C. 



2. Same as Method 1 with one-half the weight of water. 



3. Same as Method 1 with one-quarter the weight of water kept 

 between 5° and 10°C. during the preparation. 



4. Pulp ground in food chopper, no water added. 



5. Pulp and peel ground together in food chopper, no water added, 

 and paste tested (mainly for amylase). 



6. Pulp ground with twice its weight of 95 per cent ethyl alcohol, 

 filtered through heavy mushn, and centrifuged. Residue ground 

 with half its weight of water, filtered through muslin, centrifuged, 

 and residue and liquid tested. 



It may be pointed out here that upon the addition of Lintner 

 starch solution to unripe banana extract, a precipitate was imme- 

 diately formed. With ripe banana extracts there was no precipitate. 

 With the unripe extract filtered through paper, upon the addition of 

 Fehling's solution to determine the enzyme actions, a gelatinous pre- 

 cipitate was formed. Only small portions could therefore be used 

 for the tests as otherwise filtration through the Gooch crucibles was 

 difficult. No such difficulty was experienced with ripe banana 

 extracts. Toluene was used as preservative throughout these experi- 

 ments. 



The general results of the enzyme tests were as follows : For amylase 

 action, in no case were the results such as to show definitely the 

 presence of this enzyme. In a few experiments small apparent 



