Volume 20 (2002): Issue 1 (February 2002)

Leaf samples of different flue-cured Virginia tobacco varieties were analyzed and compared to a standard, the typical American Virginia cultivar K 326. Plants were grown in the Plovdiv region, Bulgaria, under conditions appropriate for Virginia varieties. The tobaccos were characterized by means of high performance liquid chromatography (HPLC) of polyphenols and capillary gas chromatography (CGC) of the neutral volatiles of essential oils, as well as by a sensory evaluation of color and aroma. All cultivars examined contained twelve polyphenol components in their HPLC profiles and differed only in quantitative aspects. Both qualitative and quantitative variations between the CGC profiles of essential oils of the cultivars were observed. The chromatographic profiles of polyphenols and essential oils were compared by the pattern recognition method (PRM) and used for calculating the similarity indexes (I_s,%) of the samples to the standard Virginia variety K 326. The chemometric data obtained are completely compatible with sensory evaluation of color and aroma. Based on the results obtained the tobaccos may be distinguished as: typical full-flavored Virginia - aromatic (Virginia 330); typical full-flavored Virginia - less aromatic (Virginia 0454); non-typical (filler type) Virginia (Virginia 42). The possibilities of the PRM for objective evaluation of color and aroma of Virginia tobaccos were demonstrated.

Previous work has demonstrated potential handling and curing efficiencies in the use of cut-strip tobacco. The present work considers further the effect of cut-strip size, packing density and mode of orientation on cured leaf chemistry (starch, reducing sugars, and total alkaloids) and leaf quality. Results showed that cured leaf chemistry of 15.2 × 22.9 cm cut-strip more closely matched properties of whole leaf than pieces 15.2 × 15.2 cm or smaller. Starch contents were significantly higher for the smaller cut-strip sizes, perhaps due to edge drying effects, while alkaloids were significantly lower. Within the range of 194 to 292 kg/m, packing density had little effect on leaf chemistry, with the exception that reducing sugars were slightly lower for the higher packing densities. This could be due to a longer time for the drying front to move through the more tightly packed tobacco, and hence more respiratory loss of sugars. Government grades and average market prices of cured strips were essentially unaffected over the range of strip sizes or packing densities tested. Based on airflow resistance measurements and observed drying characteristics, vertical orientation of strips was far superior to horizontal orientation, both with vertical airflow through the tobacco. The higher packing density reduced specific energy use (kWh/kg green tobacco) by as much as 22%, indicating potential energy savings for cut-strip over whole leaf curing.

Among the insect species causing infestations and serious damages to stored commodities, the cigarette beetle, Lasiodermaserricorne (F.) and the tobacco moth, Ephestiaelutella (Hübner) are the major pests of both raw and manufactured tobacco. Post-harvest tobacco control is achieved through sanitation, insect monitoring, and fumigation with phosphine. However, insect resistance to phosphine and control failures have been reported, and increasing regulatory pressure is being exerted on fumigants. Biological control agents such as Bacillus thuringiensis (Bt) appear to be environmentally sound and potentially viable alternatives to chemical control. Bt is a bacterium that produces insecticidal crystal proteins during the sporulation phase and has been, for more than 40 years, the microorganism of choice for the biocontrol of phytophagous insect pests. It produces insecticidal crystal proteins that display specific activity against certain orders of insects and become active upon ingestion by the insect. Our laboratory has conducted extensive research and worldwide surveys to evaluate the presence of Bt in stored tobacco and has confirmed previous findings indicating that Bt may be considered part of the naturally occurring phylloplanemicroflora. Several Bt strains were isolated from tobacco and characterized by DNA and protein profiling. The insecticidal activity of selected strains and of two commercial products against the larvae of L. serricorne was determined by diet incorporation assays. Moreover, the stability of Bt spores and crystal proteins on cured tobacco leaves was assessed over a storage period of time of 30 months. Cigarette prototypes were made with Bt-treated tobacco. Standard cigarette and smoke evaluations did not show any significant difference between the test and control cigarettes. Although the tested Bt strains and products did not yield satisfactory levels of mortality at the required times and doses, the experimental results summarized in the present review indicate that B. thuringiensishas potential for the control of the cigarette beetle. The integration of conventional control approaches with novel systems based on biological agents with different modes of action should offer new avenues for the effective management of stored tobacco pests in line with integrated pest management (IPM) concepts.

Bialous and Yach have recently published an article in Tobacco Control in which they claim that all smoking-machine standards stem from a method developed unilaterally by the tobacco industry within the Cooperation Centre for Scientific Research Relative to Tobacco (CORESTA). Using a few highly selective quotations from internal tobacco company memos, they allege, inter alia, that the tobacco industry has changed the method to suit its own needs, that because humans do not smoke like machines the standards are of little value, and that the tobacco industry has unjustifiably made health claims about low “tar” cigarettes. The objectives of this paper are to review the development of smoking-machine methodology and standards, involvement of relative parties, outline the significance of the results and explore the validity of Bialous and Yach's claims. The large volume of published scientific information on the subject together with other information in the public domain has been consulted. When this information is taken into account it becomes obvious that the very narrow and restricted literature base of Bialous and Yach's analysis has resulted in them, perhaps inadvertedly, making factual errors, drawing wrong conclusions and writing inaccurate statements on many aspects of the subject. The first smoking-machine standard was specified by the Federal Trade Commission (FTC), a federal government agency in the USA, in 1966. The CORESTA Recommended Method, similar in many aspects to that of the FTC, was developed in the late 1960s and published in 1969. Small differences in the butt lengths, smoke collection and analytical procedures in methods used in various countries including Germany, Canada and the UK, developed later, resulted in about a 10% difference in smoke “tar” yields. These differences in methodology were harmonised in a common International Organisation for Standardisation (ISO) Standard Method in 1991, after a considerable amount of interlaboratory comparisons of the developing methodology had been undertaken by CORESTA. As acknowledged by Bialous and Yach, the purpose of the standards is to determine the “tar”, nicotine and carbon monoxide content of cigarette smoke when the cigarette is smoked under precisely defined conditions, and hence to allow a comparison of the yields from different cigarettes when smoked under identical conditions. Such yields are not predictive of the yields humans obtain when smoking, nor were they ever expected to be so, since no two smokers smoke exactly the same nor does a smoker smoke a cigarette the same way on every occasion. This purpose has been stated consistently many times, originally by the FTC in 1967 and subsequently in the scientific literature, published by the tobacco industry and health/regulatory authorities, over the last 35 years. From the 1950s onwards numerous public health scientists have advocated that lower “tar” cigarettes should be developed on the grounds that they may reduce to some extent the risks of smoking, while at the same time advocating that the best way to avoid risks is not to smoke. Some health authorities have have used the standard machine-smoking yields to set limits on “tar” as a way of reducing the health impact of cigarette use. The tobacco industry has co-operated with these health authorities by developing cigarettes with lower “tar” but has also followed public health advice by not advertising lower “tar” cigarettes as safe cigarettes. The available evidence, taken as a whole, indicates that compensation by smokers who switch from a high to a low “tar” cigarette is partial in the short term, and that such smokers do obtain a reduction in smoke component uptake.

In order to reduce the nitric oxide (NO) and nitrogen oxides (NO) content in mainstream tobacco smoke, a new class of catalyst based on Cu-ZSM-5 zeolite has been synthesized. The effectiveness of the new catalyst (degree of reduction and specific catalytic ability) was tested both by adding Cu-ZSM-5 zeolite directly to the tobacco blend and by addition to the filter. We have determined that adding the catalyst to the tobacco blend does not cause any changes in the physical, chemical or organoleptic properties of the cigarette blend. But, the addition reduces the yield of nitrogen oxides while having no influence on nicotine and “tar” content in the tobacco smoke of the modified blend. The catalyst addition increases the static burning rate (SBR). The changes in the quantity of NO and NOmay be explained by changes in burning conditions due to the increase of Oobtained from catalytic degradation of NO and NO, and adsorptive and diffusive properties of the catalyst. The changes in mainstream smoke analytes are also given on a puff-by-puff basis.