Tobacco processing

PLANT

When America was discovered by Columb, mankind has received four plants, which have played a great role in economical and industrial development. The above mentioned plants are: tomato, potato, paprika and tobacco. We are going to deal with tomato and potato afterwards but now let it be tobacco. Tobacco is an annual plant. Its roots do not put down deep into soil, however mature plant can reach three metres height depending on the conditions and the grade. In the course of longstanding practice there was bred more than one hundred grades of tobacco and all of them were produced from two main species. That is Virginia |Tobacco (Nicotiana tabacum L.) and Rural Tobacco. Virginia Tobacco reachs two metres height and one plant have from 8 to 20 leaves that reach 60 centimeters of length. It was this very species from which were bred most of the grades of tobacco which are used for manufacture of quality product. Maryland Tobacco as well as Kentucky, Berly, Semi-Virginia and the other ones are also used in tobacco production except for Virginia Tobacco.
Rural Tobacco grows for cheap cigaretes and tobacco. By the way, Russian makhorka (poor tobacco) is the variety of Rural Tobacco. Height of this type is no more than one metre and it is rather undemanding to climatic conditions. That is why, it is apparently get acclimatized in Russia. The tobacco plant as well as some other plants of this family contains nicotine which has a stimulatory action in small quantities.And as is well known, it is enough the only one drop of it to kill a horse. Everything is poison as well as everything is medicine as was said by one of the intelligent person.
Besides, it is clear that tobacco has also different aromatic and taste qualities.
Tobacco seeds are quite diminutive. The obly gram of it has some 12.000 and the only one seed is enough for growing the one plant as evident. That is to say, it is enough only some grammes of seeds for sowing the whole tobacco field.

SPROUTING

BEDDING OUT

In the regions where a lot of sunshine, for example in Cuba, tobacco plantations will be covered with thin and light sheds to cast a shadow on them. This method needs great expense but then there will be perfect leaves, especially suitable for outside covering of the cigar leaves.

HARVESTING

When the tobacco leaves are definetely mature, it is time to harvest. Commonly it is happened after 2-3 months have passed after bedding out when leaves are turning to deep-green color.

Harvesting of cigarette tobacco is always reaped only by hand as the bottom leaves are ripened initially. That is why harvesting of leaves is reaped in some of the stages. It is considered that the most qualitive are those leaves that are in the middle part of stalk .

DRYING

There is 85 % of water in the tobacco leaf when it is fresh. By drying, this percentage should be to about 25 % At the time of drying leaves change their color into yellow or brown ones.

When the usual air-curing is used in terms of cigarette tobacco for instance, time and temperature is regulated with the help of ventilation of drying room. For this, the transom is fixed in the walls and roof. As for the drying rooms, for the most part they are made of wood.
During the first stage of drying all the transoms are closed. Later when the leaves are turning the necessary color, drying rooms are completely opened.
Air-curing process usually lasts from 5 to 10 weeks, depending on the climatic conditions.
Another metod of drying is so-called Fire-curing which was invented in the USA. As a general rule it is used for pipe or cigarette tobacco which should have especially light color, for instance Virginia. Here, the point is that all of it lies in the pipe which extends through all the drying room and on which the heat is supplied. Advantage of this method is that in addition to receiving especially light tobacco, it also takes much less time. The whole process takes altogether 4-5 days.
As for the rest of the drying methods, it is worth to mention Sun curing. However, there is not so much space on the ground where the climate allows to dry tobacco out of doors. That is why it is preferable to use combination method, which consists of sun-curing and air-curing.

Chemical processes which happens in tobacco during drying process is continuing to be during fermentation. Because of fermentation starch is turning into sugar, nicotine content is reduced; proteins are also decaying into elementary substances. Exactly at this stage raw material turns into tobacco that we know.

Dried tobacco is tied into small bunches which is consequently packed up into big sheaves, 4-5 ton each. Shortly after that, the temperature is starting to rise in tobacco. To control temperature, during packing up into sheaves, from the middle to the edge, hollow bamboo sticks are introduced in which for its turn thermometers are inserted. Non-observance of thermal behavior can lead to aromatic oils, which have an influence on taste of tobacco can be burnt out. In 4-5 days when the temperature in the middle of sheaf achieves 55-60 degree, sheaf is separated and tobacco is quickly refrigerated. After that it is packed up into sheaves once again, but in such a way that tobacco that was earlier in the middle was found nearer to the edges and vice versa. The temperature in the sheaves is once more starting to raise but some slower. When the temperature achieves 60 degree, tobacco is placed elsewhere and it is continuing until the temperature does not stop rising. It takes usually 5-6 stowage for achieving this. After that tobacco is prepared for packing into so-called Serones, briquettes weighing 60 kg which are transported to the factories.

A LITTLE CHEMISTRY

Chemistry of tobacco depends on its type, conditions of growing, method and time of harvesting and largely on composition of the soil.
Fresh-collected leaves contain 80-90% of water, after drying in leaves remains less than 33% of water. In two main tobaccos (Virginia, Burley), the left 66% contains the following components:

(Virginia)
15-25% carbohydrates
16% alkali substances
10% different acids
10% minerals
6% pectin
1-3,5% nicotine

(Burley)
20% different acids
10% pectin
10% pitch
8% calcium
7% nitrogen
6% potassium
1,5-4,5% nicotine

Acidity (PH)
Virginia 5,0
Burley 5,8

It is clear that smoker is more interested not in tobacco leaves composition but in tobacco smoke composition, though there is a close connection between them.
So, according to chemical reaction of smoke one tell about two groups:
1. alkaline, these are Burley and Kentucky
2. acid - Virginia and Orient

Smoke of the alkali group is dry, practically without sweetness and has a big content of nicotine.
As for the smoke of the acid group, it is sweet and has less nicotine in its content.
Kentucky, consequently is stronger, and Orient is smoother tobacco in its groups.
Thus, by mixing two main tobacco - Virginia and Burley, necessary balance can be achieved between dryness and sweetness and at the same time the quantity of nicotine is regulated.
In their own laboratories, large tobacco factories make an analysis of trial purchase of raw material before purchases of great lots are made. At that, the following parameters are examined:
1) Taste and aroma
2) speed of burning
3) color and appearance of the tobacco
4) moisture
5) nicotine content.

Speed and easiness of burning, for instance it is better for Burley than for Virginia because of big content of potassium in Burley. It is clear that the moisture is of importance, which should be within the limits of 12-18% of prepared tobacco.
As to nicotine, tobacco strength is defined by the following manner::
0,6-1% - light
1-2% - medium
2-3% - strong
3-4% - extra strong
Tobacco, which has a content of 4%, is considered as unsuitable for using as a tobacco for smoking. Nicotine content depends not only on the type of tobacco but also on the time of harvesting and on the drying method. Late harvesting as well as quick drying gives tobacco more nicotine content. As for the tobacco bush, its content is increased from the bottom leaves to the upper ones.