.February, 1910.] 109 



DRUGS AND MEDICINAL PLANTS. 



THE FERMENTATION OF CIGaR- 

 LEAF TOBACCO. 



By J. C. Brunnich. 



(From the Queensland A gricultural 

 Journal, Vol. XXIII., Pt. VI., Dec, 1909.) 



The fermentation or sweating of cigar- 

 leaf tobacco is of the greatest import- 

 ance to produce an aromatic leaf, free 

 from harsh, bitter or other objection- 

 able taste. A large amount of work 

 of investigating this process has been 

 carried out in the United States of 

 America, and the results of the experi- 

 mental work with Florida and Connecti- 

 cut cigar-leaf are given in Report No. 

 60 — "Temperature Changes in Ferment- 

 ing Piles of Cigar-leaf Tobacco," by 

 Milton Whitney and Thos. H. Mears. 



In the course of these experiments 

 Dr. Loew made an examination of the 

 different leaves, which led to a dis- 

 covery of the greatest practical im- 

 portance. Dr. Loew proved that the 

 curing and fermenting of tobacco is not 

 due to the action of certain bacteria 

 as stated by many authorities, but is 

 caused mainly by the oxidising action 

 of soluble ferments or enzymes, called 

 oxidase and peroxidase. He showed 

 that the formation of these important 

 organic compounds can be increased by 

 certain treatment of the leaves, as by 

 slow drying of the leaves in barns or 

 sheds, and, again, can be completely 

 prevented from developing when the 

 leaves are suddenly dried by a dry 

 warm wind. 



For the most favourable development 

 of the oxidases a suitable amount of 

 moisture in the leaves is an absolute 

 necessity, but an excess of moisture 

 again will be detrimental. The presence 

 of the enzymes, oxidase, and peroxidase 

 is absolutely necessary to produce the 

 proper fermentation of the tobacco 

 leaves, which takes place with a con- 

 siderable rise of temperature. The 

 Florida leaf shows a particular vigorous 

 fermentation, with great heating, where- 

 as the Connecticut leaves fermented 

 slowly without much increase of tem- 

 perature, and, therefore, the fermenta- 

 tion failed to destroy by oxidation 

 many of the undesirable substances con- 

 tained in the tobacco. 



Mr. R. S, Nevill, the Tobacco Expert 

 of our Department, noticed a similar 



trouble in some of the cigar-leaf to- 

 bacco grown at Bowen, and he submit- 

 ted two samples of cigar-leaf from the 

 same crop to be tested in accordance 

 with Dr. Loew's method for the presence 

 of oxidase and peroxidase. One of the 

 samples— unfermented leaf — had hung in 

 the sheds for months, subject to weather 

 changes, the other sample — fermented 

 leaf — was stripped and packed in boxes 

 early in the season. 



The fermentation was unsatisfactory 

 by reason of the very low rise of tem- 

 perature (106 degrees) obtained, and Mr. 

 Nevill attributes this to insufficient 

 amounts of oxidase and peroxidase pre- 

 sent. Our tests distinctly proved the 

 complete absence of both oxidase and 

 peroxidase in the unfermented leaf, and 

 the presence of peroxidase and absence 

 of oxidase in the sweated sample. 



Mr. Nevill explains the entire absence 

 of the oxidising enzymes in the unfer- 

 mented leaf to its having been so long 

 exposed to the weather changes, and 

 I believe this to be correct, parti- 

 cularly if the tobacco was dried very 

 suddenly by warm winds. That some 

 of the enzymes develop in the sweated 

 leaf shows the advantage of preventing 

 such exposure by bulking the tobacco 

 as soon as dried sufficiently. The ac- 

 curate judging of the amount of mois- 

 ture is, as already explained, of utmost 

 importance, and we will never be able 

 to produce a high-class cigar-leaf if 

 strictest attention is not paid to all 

 details of stripping, drying, and bulk- 

 ing, as all the operations have an in- 

 fluence of the amount of oxidases formed 

 in the leaves, and without the presence 

 of oxidases a proper fermentation is an 

 impossibility. Based on this investiga- 

 tion, Mr. Nevill makes the following 

 suggestions :— Drying-sheds should be 

 made of grass or wood, to be closed or 

 kept open as desired, so that the to- 

 bacco could be dried slowly under uni- 

 form conditions, and be protected from 

 extremes of heat and wind, so that 

 the oxidising enzymes may be developed 

 and preserved for the subsequent stages 

 of fermentation. 



It would be of particular interest if 

 next season more samples of tobacco, 

 treated under various conditions and 

 in different classes of sheds, were sub- 

 mitted to us, in order to be tested 

 similarly for the absence or presence 

 of oxidising enzymes 



