Table Of ContentTHE PENNSYLVANIA STATE COLLEGE
The Graduate School
Department of Agricultural and Biological Chemistry
STUDIES OF THE AGING OF
FLUE-CURED CIGARETTE LEAF-TOBACCO
A Thesis
Seymour Stanton Block
Submitted in Partial Fulfillment
of the requirements
for the degree of
Doctor of Philosophy
August, 19A2
Approved:
W * .TftV
Maj or^Prof essor
Head of the Department
TABLE OF CONTENTS
LIST OF TABLES
LIST OF FIGURES
INTRODUCTION
RESULTS OF PREVIOUS INVESTIGATIONS
PREVIOUS TREATMENT OF TOBACCO
A DESCRIPTION OF THE BACTERIA STUDIED
DESCRIPTION OF METHODS EMPLOYED
Chemical
Steam Volatile Acidity
Steam Volatile Bases
Steam Volatile Neutrals
Steam Volatile Aldehydes
Determination of pH
Potentiometric Measurements
Qxidation-Reduction Potentials and Poising
Effect
Viscosimeter Measurements
Moisture Relationships
Determination of Reducing Sugars
Bacteriological
Determination of Bacterial Numbers
Isolation and Morphology
Utilization on Sugars
Metabolism on Nitrogen Compounds
PRESENTATION OF THE EXPERIMENTAL RESULTS
DISCUSSION OF THE RESULTS
SUMMARY AND CONCLUSIONS
ACKNOWLEDGMENTS
BIBLIOGRAPHY
LEST OF TABLES
I* Aging Samples of Flue-Cured Cigarette-Leaf Tobacco of
the 1938 Crop
II* Aged and Unaged Flue-Cured Cigarette-Leaf Tobacco
Samples Used in These Studies
III. The Total Steam-Volatile Acids and Bases, and pH of
Aged and Unaged Flue-Cured Cigarette-Leaf Tobaccos
IV. The pH of Aging Flue-Cured Cigarette-Leaf Tobaccos
V. Potentioraetric Titrations of the Extract of Aged and
Unaged Flue-Cured Cigarette-Leaf Tobaccos
VI. The Drift in the Oxidation-Reduction Potentials of the
Extract of Aged and Unaged Flue-Cured Cigarette-Leaf
Tobaccos
VII. The Drift in the Oxidation-Reduction Potentials of the
Extract of Aged and Unaged Flue-Cured Cigarette-Leaf
Tobaccos
VIII. Viscosimeter Measurements on Aged and Unaged Flue-
Cured Cigarette-Leaf Tobaccos
IX. Moisture-Holding Capacities of Aged and Unaged Flue-
Cured Tobaccos
X. Bacteriological Assay of Aging Flue-Cured Cigarette-
Le^f Tobaccos
XI. Bacteriological Morphology of Aging Flue-Cured Cigarette-
Leaf Tobaccos
XII. Bacteriological Assay of Virginia Cigarette-Leaf Tobacco
from Flue-Curing to One Year of Aging
XIII. The Development of Molds on Aged and Unaged Flue-Cured
Cigarette-Leaf Tobaccos after Exposure for One Week
Over Distilled Water at Room Temperature
XIV. The Rate of Reproduction of Bacteria Isolated from Aging
Flue-Cured Cigarette-Leaf Tobaccos in Media Containing
Pure Organic Nitrogen Compounds
XV. The Oxidation-Reduction Potentials and Drift in Potentials
of Aged and Unaged Flue-Cured Cigarette-Leaf Tobaccos
LIST OF FIGURES
The Distillation Apparatus for the Determination
of the Volatile Constituents of Tobacco
Potentiometric Titrations of the Extract of Aged
and Unaged Flue-Cured Cigarette Tobacco
The Drift in the Oxidation-Reduction Potentials
of the Extract of Aged and Unaged Flue-Cured
Cigarette Tobaccos
The Effect of the pH on the Oxidation-Reduction
Potential of Tobacco Extract Sample No. 361
Mold Growth on Aged and Unaged Flue-Cured
Cigarette-Leaf Tobaccos After Exposure Over
Distilled Water for One Week at Room Temperature
The Utilization of Mono- and Disaccharides by
Types of Bacteria Isolated from Aging Flue-Cured
Cigarette-Leaf Tobaccos
INTRODUCTION
AND
RESULTS OF PREVIOUS INVESTIGATIONS
INTRODUCTION
Before flue-cared tobacco is ready to be manufactured into
cigarettes there elapses a period from two to three years of Maging.”
During this process of aging there develops in the tobacco the aroma
and mildness necessary for good smoking* As well as causing the
tobacco producer to risk buying for a market three years hence,
there is the expense and care connected with the storage of the
tobacco. To add to the uncertainty is the natural quality of diff-
t
erent tobaccos with respect to the aging process* Some tobaccos age
much more readily than others, and some will not age properly.
These are some of the problems of the tobacco manufacturer
with regard to aging of tobacco* If the changes that occur during
the aging process are better understood, there appears some hope that
the problems involved might be solved and the tobacco industry become
more secure. The present studies have been undertaken with this
consideration in mind.
The chief purposes of these investigations ares
1) To study some of the chemical, physical, and bacteriological
changes that occur in tobacco leaves as a result of the aging process;
2) To establish definite methods for recognizing and ascertaining the
degree of aging undergone by the tobacco;
3) To suggest, if possible, some of the mechanisms which may be re
sponsible for the desirable changes that occur during aging;
4) To reveal new methods and techniques for studying the problems
of aging so that future investigations may be facilitated.
3
RESULTS OF PREVIOUS INVESTIGATIONS
The scientific information available on the aging of flue-
cured cigarette tobacco is unfortunately very meager; the greater
portion of the work along these lines having been done on the "fer
mentation" of cigar-leaf and chewing tobacco. It has often been
necessary, therefore, to translate these results, as far as is
possible, to the process of aging of cigarette-leaf tobacco.
Since the fermentation and aging processes are decidedly unlike,
it must be pointed out that any conclusions carried over from the
former process to the latter are very likely to be invalid. It
must be noted, however, that many of the earlier workers did not
distinguish between these two processes but regarded them together
as “fermentation."
The views with regard to the fermentation and aging proces
ses generally fall into three distinct categories. They include
those conceptions which explain the above processes on the basis of
1) changes that occur as a result of purely chemical oxidations of
the leaf constituents; 2) changes that occur due primarily to the
action of the microorganisms on the tobacco leaves; and 3) changes
which result from the action of enzymes which originate in the plant
tissue. The literature will be reviewed with regard to these three
viewpoints, respectively.
Nessler (26) (27), in 1867, advanced the theory that under
the proper conditions fermentation can occur in the absence of
u
enzymic or microbial activity* Boeckhout and Ott de Vries (5) for
warded the theory that the fermentation was a purely chemical
process activated by the oxygen of the air and added that iron of
the plant acts as a catalyst for the oxidation* According to Loew
(23), ‘’repeated efforts have been made to replace the sweating or
fermentation process by a direct oxidation. Dr. Mew, of the Army
Medical Museum in Washington, assures the writer that experiments
made by him about twenty years ago to improve the cured tobacco
leaf by direct application of a dilute solution of potassium per
manganate resulted in an essential improvement. Similar results
have also been mentioned by Kiessling (19). In Germany a patent has
been granted by the firm of S iemens and Halske for treating tobacco
with ozone.'’ The absorption of oxygen by yellow tobacco in the
process of fermentation has been used as a measure of the fermentation
by Smirnov (39) and is called "the oxygen number".
The most recent and staunchest support of the chemical oxi
dation theory, with respect to flue-cured cigarette tobacco, is given
by Dixon et al (7) of Duke University. These workers are convinced,
as a result of their experiments on aging tobacco, that bacterial,
fungous, and enzymic action, if at all related to the aging process,
certainly play a minor role. They suggest the mechanism that during
aging there is a reaction between the sugars and amino acids of the
leaf to produce "melanoidins", (1), with the liberation of carbon
dioxide. Favoring this theory they find 1) significant losses of
amino nitrogen and reducing sugars during aging, 2) melanoidins made
