33 B.i^-^"'^'^ 



Auother instauce where an oxidizing enzym plays a part in a technical 

 branch is the "fermentation'' of the olive, which is practiced in certain 

 parts of Italy. It is believed that by this oi)eration an oil of superior 

 quality is obtained and that the yield by pressure is larger, but this 

 has not been confirmed. It has been shown by Tolomei^ that this olive 

 '"fermentation" is due to the action of an oxidizing enzym, to which 

 also is due the fact that olive oil is bleachable by sunlight. 



When the freshly gathered olives are kept in sacks their temperature 

 gradually rises far above that of the rooms, oxygen is absorbed, and 

 carbonic, acetic, and sebacic acids, and small quantities of the higher 

 volatile fatty acids are formed. This process goes on to a larger 

 extent when a temperature of 35° C. (95° F.) is reached. These changes 

 do not occur if the olives are kept in nitrogen or carbonic acid gas; 

 neither do they occur when the olives have been heated to 75° O. (167° F. ) 

 for forty five minutes. For obvious reasons the spontaneous rising of 

 temperature is noticed only when a large number of olives are kept 

 together. Tolomei showed that the oxidase extracted with water and 

 purified by a repeated precipitation with alcohol produces guaiac blue 

 from guaiac tincture, forms purpurogallol from pyrogallol without the 

 aid of peroxide of hydrogen, quinhy drone from hydroquinone, and 

 a brown substance from gallic acid. He calls this oxidizing enzym 

 oiease. As unripe olives do not contain this olease, the oil pressed from 

 them will not bleach upon exposure to the sunlight, but will do so after 

 being shaken with an aqueous extract of the ripe olives. On the other 

 hand, olive oil will sooner acquire rancidity in the presence of the olease 

 than when free from it. 



Finally, still another case may be j)ointed out where oxidases might 

 possibly play a part — that is, in the so called fermentation of the cacao 

 beans, by which a bitter princii^le is destroyed. 



SUMMARY. 



(1) The so called tobacco fermentation is not caused by bacteria. 



(2) The amount of water i^resent in normally fermenting tobacco 

 leaves is insufficient to bring nourishment for the microbes from the 

 interior of the cells to the surface of the leaves. It barely suffices for 

 imbibition of the organic matter. 



(3) There exists no bacterial coating on the fermenting tobacco leaves 

 under normal conditions, but some spores may occur. 



(I) In the so-called petuuing of tobacco an immense number of bac- 

 teria may be transferred to the leaves. These bacteria, however, are 

 not essential for the fermentation, but on the contrary, may prove 

 noxious as soon as a small surplus of water enables them to further 

 develop. 



(5) Suchsland's theory that the aroma of tobacco is caused by spe- 

 cific bacteria is incorrect. 



' Atti della Reale Accademia del Lincei, 1896, p. 122. 

 15840 3 



