REHANDLING AND FERMENTATION OF TOBACCO LEAF PRIOR TO MANUFACTURE
SELECTION OF LEAF. TREATMENT AND BLENDING. OBJECTS AND METHODS OF
FERMENTATION. ACTION OF MICROBES.
REHANDLING AND FERMENTATION OF TOBACCO LEAF PRIOR TO MANUFACTURE
We have seen how the tobacco passes from the grower to the manufacturer or
leaf dealer. Before it is fitted, however, for manufacture into cigars or
other finished products the leaf must go through many processes, the most
important of which is fermentation. These processes, which are usually
known as rehandling, are carried out in special buildings which are called
leaf houses and stemmeries. The procedures in different leaf houses may
vary somewhat, but the general principles and objects in view are the same
in all. Moreover, the treatment is different, according to the ulterior
disposition of the leaf, i. e. whether intended for cigars, pipe smoking
or other product.
The general treatment as carried out in large establishments is about as
follows:
The leaf as soon as it is received whether in casks, cases, bales, or
otherwise is opened up and inspected in the casing room. Large concerns
which manufacture or deal in cigar and other kinds of leaf, sort out the
different kinds suitable for each class of product, i. e. wrappers,
fillers, binders, cigarette leaf, plug leaf, etc. These are distributed
to either special houses or departments. The tobacco leaf when first
received is usually dry and brittle. The bundles are carefully opened up
and the leaves loosened and spread out on large trucks where they are
sprayed with water. When the leaf has soaked the water and is pliable it
undergoes a sorting which is done by selecting leaves from different cases
or even bundles of leaves and in a general way arranging them so that each
truckfull represents a blend of the different kinds of leaf which are
suitable for the purpose in view. These sorted packages are then roughly
fastened together and after being again sprinkled thoroughly are sent to
the "sweating" room to undergo fermentation which may last several weeks.
The temperature of this room must be carefully regulated and is usually
kept at about 90 deg. F.
The selection and blending of the different kinds of leaf is most
important. It requires accurate and expert knowledge in choosing leaves
and kinds possessing different strengths and other qualities and in
combining them in such proportions that the final effect of the blend
gives just what is required.
It is particularly in this expert treatment of the leaf before manufacture
that the greatest advance has been made in the tobacco industry. The
smoker has the advantage and satisfaction of knowing that not only does he
get the benefit of improved scientific knowledge and sanitary conditions
by which anything that might be harmful or undesirable is removed, but
that handling the leaf in large quantities effects great economics and
procures for him the benefit of choicest selected grades at a reduced
cost.
It may be said here incidentally that leaves of the very best tobaccos
which are defective merely in size, or color, etc., are put through
exactly the same processes as the choicer quality leaves, and are used in
the manufacture of the popular priced machine-made "little cigars" and
"cheroots."
It will be necessary now to digress for a short time and consider what
happens during the process of fermentation.
FERMENTATION OF TOBACCO
The fermenting of tobacco leaf has for its principal objects, (1) the
removal of acrid matters, (2) the fixing of the color, and (3) the
production of flavor. Fermentation can only take place under suitable
conditions of heat and moisture, and is essentially a chemical process
during which certain organic compounds stored in the plant are split up
and others formed.
A certain amount of fermentation takes place in the curing houses during
the "yellowing" of the leaf after it has been harvested, but as we have
seen the main process of fermentation does not occur until it is
"rehandled" by the manufacturers.
The general opinion held at present as the result of investigation is that
the transformations which are effected in the leaf are purely the result
of chemical processes. As the plant slowly dies and decomposes special
ferments are produced. These ferments set up an oxidization process which
splits up the complex organic compounds which still exist in the leaf
cells. The starch in the plant is changed into sugar which is slowly
consumed. There is a decrease in the fats and gummy substances, also in
nicotine and nitrogenous compounds, and there is a formation of certain
organic acids such as malic, citric and oxalic which are essential in the
production of flavor. Briefly it may be said that the process is an
attempt by the plant to prolong its existence by feeding on its own
substance, by drawing on its own reserves and on its own structure for the
food which its cells no longer receive through the natural growing
process. When the struggle is over the "fermentation" is complete. The
necessity for maturing tobacco has long been known but the exact nature
of the changes that take place during the process were not understood.
Since the discoveries of Louis Pasteur regarding the part played by
bacteria in general fermentative processes it has been generally claimed
by bacteriologists that the changes wrought in the leaf and the production
of flavor are solely the work of bacteria. Although this view has not been
proved it has never been fully disproved, and there appears to be no doubt
that the microbes known to exist in the leaf during the fermentation
process play an important part in the process. Fermentation can only take
place as stated under suitable conditions of heat and moisture and these
are the conditions which favor the development of microbes and enable them
to work. The results obtained are probably partially due to chemical
action and partly to bacterial action, the two being complementary to each
other.
In 1899 Suchsland, a German scientist, startled the tobacco world by
asserting that the flavor of tobacco was in no way due to the effects of
the soil and climate where it was grown, but was solely due to microbic
action, and that the specific flavor and aroma of any given tobacco could
be artificially produced by the cultivation of selected bacteria and
allowing the tobacco to cure and ferment under their action. He conducted
a series of experimental investigations in which he searched for and
isolated the specific microbes found in the best West Indian tobacco. From
these he made artificial cultures and introduced them into heaps of
inferior, coarse German tobacco which was undergoing curing. His results
were such that the smoking quality of the leaf was entirely changed. It
could scarcely be distinguished from the best Cuban tobacco and experts
and connoisseurs failed to identify the product as German tobacco. A
company was formed to exploit the new ideas commercially, but it does not
appear to have met with success. Other investigations failed to obtain
Suchsland's results and extensive investigation in the Agricultural
Experimental Station in the United States have not up to now produced any
results confirmatory of the theory.
We can now proceed to follow the course of the tobacco in its
peregrinations through the leaf house.
On their return from the first fermentation the bundles go to the picking
department. Leaves which are damaged or unsuitable in any way are here
picked out and put aside to be used in the cheaper grades. The leaves are
then subjected to a thorough cleaning to remove particles of sand, clay,
etc., packed tightly in bundles and returned to the sweating department
to undergo further fermentation and to allow for a thorough interchange of
the aroma of the different blends. In due course the bundles pass to the
stemming department for the removal of the midribs which usually form
nearly one-third of the entire weight. The resulting half leaves are then
arranged in piles of 50, each pile forming a "book."
From the stemming department the books pass to the drying room where any
superfluous moisture is removed by hot air currents.
From the drying room the books pass to the ordering room where they
undergo inspection for color, size, etc., and subjected to further
treatment if necessary. Here they are finally packed in cases and stored
for several months to allow perfect and uniform blending after which they
are ready for shipment to the factory. Filler leaf for the finest cigars
may stand in these cases for two or three years.
Leaf which is intended for chewing or pipe smoking is not subjected to so
great an elaboration of processes as cigar leaf, as the matters of
uniformity of color, and delicacy as well as individuality of aroma are
not of such great importance. Usually such tobacco leaf is fermented in
bulk, and the removal of the stems is done before the principal
fermentation.
After the preliminary selection of varieties, sorting, stemming and
cleaning, the leaf is dipped into large vats containing flavors; and after
drying are subjected to steaming. They are then packed away in bulk in the
sweating department where they slowly ferment until required for use.
These "bulks" or stacks may contain many tons of leaf. They require
constant turning over, etc. Indeed it may be said that every step in these
processes requires constant care. Temperature, moisture, length of
exposure, etc., must all be carefully seen to. Otherwise the tobacco will
spoil.
In the case of tobacco leaf intended for export trade rehandling consists
mainly of stemming and removal of moisture. This is done before shipment
in order to reduce the weight as customs duty is levied in accordance with
the weight of the imported packages in the countries importing.
REFERENCES
U. S. DEPART. OF AGRIC. _Farmers' Bulletins_ 6 and 60.
LAUREUT, L. _Le Tabac, sa culture et sa preparation, production et
consommation._ Paris, 1900.
BOUANT, E. _Le Tabac; culture et industrie._ Paris, 1901.
BOEKHOUT UND DE VRIES. _Uber Tabacfermentation._ "Centralbl. f. Bakter,"
1909. 2 Abteil. Vol. 24, p. 496.
LOEW, O. _Sind Bakterien die Ursache der Tabakfermentation?_ "Centralbl.
f. Bakter," 1909. Vol. 6, p. 108.
KILLEBREW AND MYRICK. _Tobacco Leaf._ Part I. New York, 1897.
SUCHSLAND, E. _Bobachtungen ueber die Selbsterwaermung des fermentierenden
Tabaks._ In "Festschrift 200-Jahr Jubel. d. Verein. Friedrichs Universit."
Halle-Wittenberg, 1894.
WOLF, JAKOB. _Der Tabak und die Tabakfabrikate._ Chapter IV. Leipzig,
1912.
HOAGLAND, J. G. _The Tobacco Industry._ In _Quarterly of the Nat. Fire
Protec. Assn._, 1907. Vol. 1, Nos. 2 and 4.
JACOBSTEIN, M. _The Tobacco Industry in the U. S._ Chapter II. New York,
1907.