After several weeks at sea, the cargo on the merchant ships returning from the New World would frequently start to emanate a particular fragrance. What was happening in these damp, airless, confined spaces packed with bales or barrels (“hogsheads”) of the finest tobacco leaves? This must have been worrying for whoever was in charge of the cargo, but in fact the “spoilt” shipment from Virginia was so desirable that it went like hot cakes amongst the smokers. Whatever strange process was triggered off during the voyage, the final result was so interesting that soon attempts were being made to reproduce it artificially.
Although there are no documents that record these events, it is reasonable to believe that this happened, based on legends and local reports. On the other hand, who knows how many random and fortuitous events occurring in different places and periods brought to light this phenomenon. There may also have been those experimenting with tobacco who sought to reproduce the process under controlled conditions, independently without outside reference, perfecting it and thereby achieving more or less the same results. Moreover, pioneers in this field could also include the Native Americans in Columbus’ time, when they buried tobacco for a while before smoking it. Even in more modern times people were unable to determine what process was underway in the bales, cases, layers and barrels of tobacco. Yet, they were not altogether unfamiliar with it, as the practice of fermentation is as old as the production of wine and cheese, and leavened bread. These fermentation processes themselves had also been accidentally discovered, often thanks to one or more “unfortunate” incidents, which were then transformed into something more controlled and rational once it was understood that the “incident” could be turned to advantage to improve the product. We now know that in specific environmental conditions during tobacco curing, certain types of bacteria are responsible for the anaerobic breakdown of organic matter involving the oxidation of some compounds with the aid of enzymatic processes. This leads to the breakdown of some molecules and the creation of others, which produces a great deal of heat. Above all, we do know that this busy microscopic activity is essential to transform raw tobacco into that magical substance that releases pleasant clouds of smoke for us.
When the raw tobacco leaves arrive in bales or barrels to be cured, they are untied or extracted from the barrels and laid out onto a large surface, where they will be sorted by size, colour and texture. This is to create piles that are as uniform as possible, ready for one of the curing methods. These methods depend on the place, tobacco type, and the final product that will be obtained. However, all these methods share some common features. For example, fermentation requires a rather humid environment with little airflow. In some cases ventilation is necessary to regulate the process, thus preventing the process from getting out of control.
As mentioned above, the method changes according to location, but there may be differences in techniques even between companies. These traditional techniques have been perfected over time, and are closely guarded secrets. The plant strain can also determine the curing method. For instance, dark tobacco leaves are thick, containing numerous substances that need to be refined and require lengthy fermentation, which results in a dark brown tobacco. On the other hand, light brown tobacco leaves are less substantial and so require less curing time. Indeed, their light colour is one of the product’s finer qualities and excessive fermentation would only darken it. The tobacco is aged through curing, a kind of bland fermentation. Other strains of tobacco with intermediate characteristics require other types of treatment, which also depends on the type of tobacco product desired. For instance, tobacco leaves for cigars require a more complex, lengthy process, whereas those selected for pipes have less complex procedures, which are still aimed at achieving high quality standards.
One of the rules for fermentation is that the more intense the process, the more moisture must be added to the leaves and the larger the mass of leaves. This is because a damp environment triggers the bacteria, which in a confined space use enzymes to break down the molecule chains in order to gain access to oxygen, and the larger the mass of leaves, the less air there will be within this mass. Thus, when the leaves are well moistened and amassed in large piles, sometimes weighing tons, the process is indeed spectacular. This type of treatment is generally used for dark tobacco, which requires fermentation. The centre of these piles of leaves may reach high temperatures, which could be hazardous and lead to spontaneous combustion. Thus, in the large barns experts are present to monitor the process and detect any unusual signs and act accordingly. They insert thermometers into the piles and if there are any risks of overheating they create holes to ventilate the leaves. The same experts regularly carefully rotate the piles so that the leaves are exposed on all sides and fermentation is uniform. The experts also have to decide when to halt the process, as excessive fermentation would ruin the tobacco. This decision is based on tobacco colour, fragrance, temperature and time, usually lasting one month.
Other processes are less spectacular, but not less effective. These involve relatively smaller stacks of selected tobacco leaves that are slightly moistened, tied into bales according to category and then either covered with burlap or packed into special boxes with movable side panels and then stacked together. The smaller the pile, the less intense is humidification and so fermentation takes longer, even several months. Although in this way fire hazard is reduced, nevertheless constant monitoring is required. The experts need to assess the stage of the process, and on the basis of certain conditions decide whether to speed it up or slow it down by acting on the bales, stacks or boxes. For example, if the side panels of the boxes are pushed inwards to reduce the space within, the fermentation process will accelerate, whereas creating more space in the boxes will provide more ventilation, thereby slowing down fermentation. Similarly, tightening the twine around the bales will speed up the process, while loosening it will slow it down. These are only a few examples of countless variations that exist based on various conditions. What is more, aromas are often added in the water used to moisten the tobacco to lend it a particular flavour, the bales are placed in large barns in which temperature and humidity are created artificially to accelerate the process, and some strains of tobacco are kept in presses while fermenting.
Once the leaves have undergone one or more different types of fermentation, they are retied into bales or covered for the curing stage. This is an extremely slow fermentation process that results in the final product. Once cured, the lighter coloured tobacco is then dried again at a high temperature, cooled down and then steamed to regain the right degree of humidity and texture. After the ribs have been removed from the leaves, the tobacco is then stored under controlled conditions where it continues to mature, an especially important process in the cases where little fermentation has occurred. The dark or light tobacco is then ready for the final stage prior to shipment. The batches of tobacco are graded according to aroma, flavour, colour and combustibility, and this determines whether they will be used for cigars, cigarettes or pipe blends. Naturally, we are interested in the last category and more will follow about what happens to pipe tobacco.