170 



as well as during the curing and fermentation periods. New 

 chemical substances are formed and others are decomposed. The 

 final result of these reactions gives the color, texture and aroma 

 to the finished product. A change in these transformations is 

 sufficient to destroy the value of the crop." For the rest, the 

 article goes on to show, partly on the authority of Loevv, that the 

 curing process is not due to bacterial agencies, for, "if this were 

 so, it would be possible to produce any desired brand of tobacco 

 simply by inoculation," but that the changes "are due to soluble 

 ferments or enzymes, which are produced in the plant during its 

 development ;" Loew having shown the presence of diastase, oxi- 

 dases, peroxidases, proteolytic enzymes and cellulose-dissolving 

 enzymes. In elaboration of this theory the article says that the 

 enzymes are in the nature of proteins, and are present in the 

 protoplasm of the cells. They are easily destroyed by excessive 

 heat or too rapid drying. In studies of these enzymes in two 

 Kentucky tobaccos, "the seed and leaves showed in every case 

 the presence of appreciable quantities of invertase, diastase, emul- 

 sin and reductase, in many cases inulase and a proteolytic enzyme 

 were also found. Soil, on the other hand, contained no enzymes 

 except in two cases. Oxidases appear to be present in the tobacco 

 leaf at all stages of its growth and gradually increase in amount 

 from the seedling stage until the topping stage, after which they 

 gradually decrease until, in the cured leaf, they practically dis- 

 appear. 



"During the curing and fermentation periods there is a great 

 loss in weight, as much as 15 per cent., about Y^ of which is solid 

 matter. Certain gases are developed, amongst which ammonia is 

 easily detected. Practically all the starch disappears during the 

 early part of the process and sugar is formed as a new product. 

 This shows the important part played by diastase. The sugars 

 also disappear, being probably destroyed by oxidases. The pres- 

 ence of invertase leads to the conclusion that cane sugar may 

 be stored in the root and afterwards translocated to the leaves. 

 The protein content of the leaves decreases considerably during 

 the ripening of the plant, also during the curing and fermentation 

 period. The presence of amino-compounds during these i)rocesscs 

 is further proof of proteolytic enzymes. The nitrates also de- 

 crease and the nicotine content diminishes. This suggests the 

 ))resence of reductase and probably there are enzymes acting on 

 the resins and gums. It is believed that the aroma of tobacco is 

 jiartly due to the decomposition products of gums and resins, as 

 well as to the breaking up of glucosides. Positive tests have been 

 obtained for a glucosifle splitting ferment. The presence of fats 

 and proteins results in tobacco of inferior flavor. They are re- 

 moved by lipeolytic and proteolytic enzymes, j)rovided the con- 

 flitions are favorable. 



"The characteristic brown color which develo])s during fer- 

 mentation is attributed to the action of oxidases. During the 



