IIG EXPERIMENT STATION RECOED. 



study of the chemical and physiological changes which occur in tobacco during 

 the process of drying the ripe leaf is a specially constructed barn and under 

 such conditions as will develop the desired properties or qualities. Very little 

 attention has been paid to this phase of tobacco curing and most of the inves- 

 tigations deal with fermentation or after-fermentation or to certain special 

 phases of the subject. 



Curing is considered essentially a vital jirocess, and this seems to be proved 

 by the fact that killing the protoplasm at very low or high temperatures or 

 with poisons, such as chloroform, prevents normal curing. Imperfect curing 

 can not, therefore, be fully corrected by subsequent fermentation. 



The results of experiments covering several years show the loss in weight 

 of dry matter in air curing when the leaf is primed (leaves picked from the 

 stalk as they mature or " ripen " and arranged on strings or sticks suitable 

 for hanging in the curing shed) or cured on the stalks, and were confined to 

 the cigar-wrapper leaf section of Connecticut. The types of tobacco included 

 in the experiments were Havana Seed, Halladay, and a so-called John Williams 

 broadleaf. It was found that " the average loss in weight of dry matter in 

 curing the picked leaves is 12 to 15 per cent, while in curing the leaves on the 

 stalk the loss in di\v weight is approximately twice as great. In other words, 

 a cigar-wrapper leaf picked from the stalk will weigh after curing approxi- 

 mately 14 to 18 per cent more than would the same leaf when cured on the 

 stalk. In the curing of the export and manufacturing types and of cigar-filler 

 types, which are harvested in a riper or more mature condition, the loss in 

 weight of dry matter is greater than in the case of cigar-wrapper leaf, fre- 

 quently amounting to 35 to 40 per cent, even when the leaves are picked from 

 the stalk in harvesting." 



In a 4-year experiment the content of pure ash of cured leaves was higher 

 than the uncured leaves and in proportion to the loss in dry weight. While the 

 green leaves contained considerable and variable amounts of starch, the cured 

 leaves were practically free, as shown by the iodin test. The cigar-wrapper 

 leaf types contain less starch at the time of harvesting than other commercial 

 types of leaf, because they are at a less mature stage when harvested and are 

 produced under conditions less favorable to the accumulation of starch during 

 the ripening period. " One of the most marked physiological differences between 

 the green and cured leaves is the content of protein insoluble in dilute acid. 

 In all cases the protein content of the cured leaves is much less than that of 

 the uncured leaves. The content of nitric acid in the green and in the cured leaves 

 is about the same. The green leaves at most contain only traces of ammonia, 

 while the cured leaves contain considerable quantities. The cured leaves con- 

 tain relatively much larger quantities of amid and amido compounds than the 

 green leaves. The relative content of total nitrogen is somewhat less in the 

 green than in the cured leaves." 



The changes produced in the leaf harvested on the stalk were the same as in 

 the leaf harvested by priming. In a 3-year experiment the composition of cigar- 

 wrapper leaf cured on the stalk and the uncured leaf were compared. "As in 

 the primed leaves, the ash content of the whole leaf is higher in the cured than 

 in the uncured leaves. The cured leaves are again practically free from starch 

 and reducing sugars, except where the curing was incomplete. The difference 

 as regards protein is similar to those noted in the cured and uncured leaves 

 in the preceding expei'iments. The differences with reference to amid and 

 amido compounds are somewhat variable, but it is evident that the cured leaf 

 does not contain appreciably larger quantities of these constituents, relatively, 

 than the green leaf, and the same is true as to ammonia. It is clear that the 

 cured leaves contain considerably less total nitrogen than the green leaves." 



