Dr. Oscar Loew 47 



and the access of air accelerates the blackening 

 process. 



A case in which tannin is changed by partial 

 oxidation for the sake of removing the 

 astringent taste is observed in the curing of 

 the fruit of certain varieties of persimmon 

 (kaki) in Japan. By the curing- process, 

 which consists in keeping the fruits in alcohol 

 vapour or in subjecting them to slow desicca- 

 tion in the sun, the tannin is changed, in con- 

 tact with an oxidizing enzyme and oxygen, to 

 a brown, tasteless substance. 1 The fruit thus 

 acquires an agreeable taste. 



Since a moderately brown colour is also pro- 

 duced in white "nibs," free of cacao red, it 

 follows that the brown colouration is not due 



facture by fermentation, and we find that we do not 

 know what is the cause of this process. If we rule the 

 pure oxidation theory as out of court there then remain 

 the enzyme theory and the micro-organism theory. The 

 former as propounded by Dr. Mann that fermentation 

 is caused by a soluble ferment or enzyme which exists 

 in the cells of the leaf, and which on being set free 

 during rolling causes the oxidation of the tannin. The 

 latter was advocated about two years ago by Dr. C. L. 

 Bernard, of Java, who claimed that fermentation is 

 caused by soluble enzymes which do not exist in the 

 cells of the leaf but in those of micro-organisms. Much 

 the same uncertainty is attached to practically every 

 branch of tea manufacture. It is surprising that a 

 Scientific Department was not created many years ago. 

 If such had been the case we should probably now be 

 "groping in the dark" to a much less extent than we 

 are. H. H. S. 



1 S. Sawamura. Ibid., 5 (1902-3), p. 237. 



