Fraction I protein is the most abundant protein in tobacco and accounts for 50 % of its soluble protein. It is composed entirely of amino acids. Its specific nutritional value is comparable with milk and surpasses that of soybeans. During tobacco combustion, Fraction I protein may contribute to the formation of HCN and other undesirable nitrogenous constituents in smoke. It can be removed from harvested leaf tobacco through homogenized leaf curing (HLC) process to improve leaf quality and usability. Considering the total world tobacco production as a whole, Fraction I protein and other soluble proteins so recovered may provide enough food for millions of people. In addition, there will also be a better smoking product
An examination of several samples of leaf tobacco, including three types of good-grade tobaccos and heavily molded flue-cured tobacco, and of cigarette smoke condensate, failed to detect aflatoxin B1. Pure aflatoxin B1 added to cigarettes was not recovered in the smoke condensate indicating that aflatoxin B1, when present, was changed or decomposed during the smoking process.
The fate of fatty compounds and surfactants used for tobacco sucker inhibition was studied with 14C-labelled materials applied to field-grown Nicotiana tabacum L. cv. Maryland Catterton plants. Residual materials recovered from test tobacco showed the following: [ 1 ] When lauric acid was used, the residual material was maintained essentially in the acid fraction.  When lauryI alcohol was used, a considerable part (9.7-24.8 %) was converted to the acid fraction, indicating possible oxidation of alcohol in the field; smaller amounts (7.4 to 14.8 %) were found in the ester fraction.  When methyl laurate was used, most (54-77 %) of the residue was recovered in the acid fraction, a small part (12.6 to 22.7 %) was found in the alcohol fraction, and the rest (10.3-23.3 %) remained in the ester fraction.  When Tween surfactants were used, nearly all the residual materials had been hydrolyzed to free polyol and fatty acids
Simple correlation and multiple regressions among 160 variables of leaf characteristics and smoke constituents were calculated, based on experimental cigarettes made from 4 cultivars of bright-type tobacco, each from 8 stalk positions. Smoke composition is a function of the botanical, physical, and chemical properties of leaf tobacco used to make the cigarette. Detailed simple correlation data, multiple-regression equations, and expressions of variety and stalk position as factors of TPM and BaP formation are presented.
Leaves taken from eight different stalk positions of four bright-tobacco varieties were used to make 85-mm cigarettes. The cigarettes were smoked under standard conditions, and the mainstream smoke was analysed for selected toxic agents. The results demonstrate that the higher the leaf on the stalk, the less its filling power and combustibility and the greater the pH, total particulate matter, nicotine, hydrogen cyanide, volatile phenols, and polynuclear aromatic hydrocarbons of the mainstream smoke. Carbon monoxide, acetaldehyde, and acrolein are found in the highest concentration in the smoke formed from leaves in the middle stalk positions. The concentration of CO2 was comparable for the smoke from the leaves of all stalk positions of a given bright-tobacco variety. These chemical-analytical data suggest that the relative potential toxicity and tumorigenicity of the smoke of bright tobacco increase with the ascending stalk position of the leaf.
A changing concept in recent years on the usability of tobacco leaf has introduced many problems that may, not fit the traditional requirements of leaf quality. Usability represents the state of being usable without adverse effects to consumers. Theoretical Model I with selected markers is proposed for the development of tobacco materials with emphasis on improving tobacco usability. This preliminary Model I is based on currently available data, and can be improved as new information becomes available. Plant scientists may use this model to develop leaf tobacco of improved usability either through breeding, selection, and culture, or by means of homogenized leaf curing and reconstitution
Effects of sucker control chemicals on cell division and differentiation were studied by observing changes in root-tip cells continuously submerged in 5 × 10-3M solutions of MH-30 (maleic hydrazide), fatty ester T-43 (methyl caprate), fatty alcohol T-148 (mixture of 1-octanol and 1-decanol), Penar (dimethyldodecylamine acetate), and surfactants Tween-20 (polyoxyethylene sorbitan monolaurate) and Tween-80 (polyoxyethylene sorbitan monooleate). No adverse cytological effects were induced by surfactants. Meristematic cells treated with MH-30 appeared to be normal but there was no cell division. MH-30 also caused fragmentation or duplication of nuclei on differentiating cells. The effects of fatty materials (T-43 and T-148) include immediate swelling of the nucleus and then a general cessation of cell division. Penar caused enlargement of differentiating cells and nuclear fragmentation or duplication, a higher frequency of binucleate cells was found to be induced by Penar than T-148 or even MH-30. In general, sucker control compounds tested in this study induced a rather low incidence of endomitotic action which was limited to certain differentiating cells.
ExperimentaI cigarettes from tobaccos varying in genotype, nitrogen nutrition, stalk position, suckering practice, and curing methods were used to examine the Ievels of N-dimethylnitrosamine (DMN) in smoke. Measurable amounts of DMN were found in all experimental samples, ranging from 1.7 to 115 ng per gram of tobacco burned. DMN content in smoke generally increased as rate of N fertilization increased. However, there were wide seasonal, cultural, and varietal effects. Burley-type tobacco produced a much higher level of DMN than the bright-type tobacco. DMN content in smoke was significantly and positively related to Ieaf total N, totaI alkaloids, nicotine, nornicotine, total volatile bases and nitrate N, but negatively related to reducing sugars. Reconstituted sheet tobaccos made with homogenized-leaf-curing samples produced much lower amounts of DMN than conventionally cured leaf. Additional information is needed to elucidate the primary leaf constituents that serve as precursors of DMN.
Fatty compounds including lauryI alcohol and methyl laurate and Tween 20 surfactant (polyoxyethylene  sorbitan monolaurate) and Tween 80 surfactant (polyoxyethylene  sorbitan monooleate) with 14C-labelling at various positions were used as suckering agents for Maryland, Burley, and bright tobacco types (Nicotiana tabacum L.) and their residues on the tobacco determined. An average residue of 1.61 ppm of fatty compounds and 1.0 ppm of surfactants were found. The combined totaI of 2.6 ppm residue due to these suckering agents is far below an earlier preliminary test of 4.8 ppm of residue in comparison with 7.000 ppm naturally occurring fatty compounds in tobacco.
A new procedure (HLC) of curing tobacco leaf through homogenization, incubation, and dehydration is described. At the homogenate stage, chemicaI composition can be improved by controlled enzyme action, by extraction, or with chemical additives. PhysicaI properties can be improved by reconstitution. Preliminary results show HLC may provide smoke with quality comparable to that from conventionally cured material, but with relatively lower biologicaI response. There is a great potential in using the HLC procedure for labour saving as well as for improving leaf usability.