1. bookVolumen 31 (2022): Edición 2 (July 2022)
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Advancements and Challenges of Cigar Science, Testing and Regulation: A Review

Publicado en línea: 15 Aug 2022
Volumen & Edición: Volumen 31 (2022) - Edición 2 (July 2022)
Páginas: 73 - 89
Recibido: 05 Nov 2021
Aceptado: 30 Mar 2022
Detalles de la revista
License
Formato
Revista
eISSN
2719-9509
Primera edición
01 Jan 1992
Calendario de la edición
4 veces al año
Idiomas
Inglés
INTRODUCTION

A cigar is defined as a roll of tobacco wrapped in leaf tobacco or in a substance that contains tobacco (other than any roll of tobacco which meets the definition of cigarette) (1). Despite the abundance of literature on the composition of traditional conventional cigarettes, published research is limited on the physical and chemical properties of cigars. Interest in expanding fundamental knowledge and standardization has increased in the last few years. Hence, there has been a marked uptick in activity from industry, academic and private laboratories with regard to research and testing designed to better understand cigar properties. For example, there were 27 presentations or publications tracked by CORESTA on the topic in 2017, approximately the same number as the previous ten years combined (2).

The overarching aim of this work has been to advance the scientific knowledge of cigar tobacco content and the resulting deliveries of select smoke constituents while developing a foundational understanding of the inherent variability of the product.

Cigars are combustible tobacco products consisting of filler, binder, and wrapper derived from tobacco. Generally, cigars of all designs fall into two main categories: Handmade/Premium cigars and machine-made cigars (MMCs). Premium cigars are typically made from whole tobacco leaves of a single tobacco type (dark air cured); are hand rolled; are usually large, with burn times of up to several hours; and are relatively expensive compared with other tobacco products. For most premium cigars, unblemished leaves are required for the wrapper. The binder is also natural leaf and the filler is hand-rolled (i.e., not cut) (3). Alternatively, MMCs are typically made using homogenized natural leaf wrapper, with or without binder, and with cut tobacco for filler. MMCs are mass produced by machines and may contain Generally Recognized as Safe (GRAS) additives and/or non-tobacco components such as a mouthpiece. In this paper we attempt to summarize and comment on recent scientific efforts and analytical testing standardization efforts by the industry, and to discuss challenges and opportunities with regard to analytical efforts for the product category.

METHODS

Approximately 1100 peer reviewed publications including extant monographs were systematically compiled from this subject-specific research. Digital data bases used to identify and screen the articles were the CORESTA website, University of California San Francisco library of tobacco industry bibliographies, FDA website and google scholar. On-line resources like Comsol (www.comsol.com) and Cigar Aficionado (www.cigaraficionado.com) were also utilized. Public health related studies, cigar consumption studies, unpublished manuscripts, thesis, dissertations and newspaper articles were considered irrelevant for meta-analysis and therefore excluded.

In situations where different articles from the same authors were cited, the articles were scrutinized to ensure that the data from each study was independent of each other and without conflicts of interest.

Figure 1 shows a pictorial illustration of our method; depicting the huge statistical differences that exist between availability of published cigar literature, cigarette literature and that of e-cigarettes. Our observations in Figure 1 highlight an extremely limited availability of cigar science research publications, therefore literature as far back a 1950 up to 2021 was utilized to capture inter-generational scientific developments and milestones in the tobacco industry. Key words/phrases searched were cigar science, cigar tobacco, cigar regulation, cigar method development, cigar chemical analysis, cigar tobacco variability, cigarette tobacco, machine-made cigars, premium cigars, handmade cigars, cigar smoke constituents and cigar tobacco farming. All the articles were collated using the EndNote referencing tool (https://endnote.com/).

Figure 1

Statistical hierarchy of review method findings based on (a) general tobacco literature search and (b) cigar science literature search for about 1100 peer reviewed publications.

SOURCES AND ATTRIBUTES OF CIGAR VARIABILITY
Demographic variability of cigar tobaccos

All testing, whether content or yield related, are impacted by the tobacco and ultimately the growing conditions of that tobacco. There have been recent efforts to increase understanding in this area for cigar tobaccos. Some have argued that testing and reporting multiple constituents in cigar leaf and smoke without having in-depth knowledge of what drives the variability/variations will engender the submission of somewhat valueless and inconsequential data to the regulatory institutions (4). Generally, controls to minimize year-to-year variability from seed planting and harvesting to the finished tobacco leaf remain a challenge. Variability in cigar tobacco is a well-known issue and FDA has acknowledged that blend changes due to “natural variability” do not require a product to undergo premarket review

Deeming Tobacco Products to be Subject to the Federal Food, Drug, and Cosmetic Act, as Amended by the Family Smoking Prevention and Tobacco Control Act; Restrictions on the Sale and Distribution of Tobacco Products and Required Warning Statements for Tobacco Products, 81 Fed. Reg. 28,974, 28,996 (published May 10, 2016) (the “Final Deeming Rule”).

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Cigar tobaccos, like cigarette tobaccos, have defined categories (such as dark air-cured and sun-cured tobaccos). Within each of the categories are numerous sub-types such as Sumatra, and Jatim), and varieties (such as Vuelta Abajo). Unlike cigarette tobaccos, cigar tobaccos have little to no standardization and are typically local varieties produced from suppliers and even farm-based selections. Unlike cigarette tobaccos, there are limited varieties produced through any type of seed certification process. So, though the total number of cigar tobacco varieties is much lower than that of cigarette tobaccos, standardization is significantly lower for cigar seeds and the range in seed sub-types and varieties is much greater (3, 4). In addition, the soil and climate conditions of the growing area are significant factors impacting variability of cigar tobacco physical and chemical properties (5). Knowledge of the relationship between the different types of soil, climate and the varieties of crops allows tobacco breeders to produce and distribute seeds specifically adapted to specific growing locations. For example, LUNDH affirmed that the strength, elasticity, thickness and shining quality of cigar wrappers strongly depends on the type of soil and climate in which the tobacco seed is planted. He claimed that even when Nicaraguan seed is planted in Ecuador, the tobacco wrapper produced is very different from a native Nicaraguan wrapper. He explained that the humidity from the constant cloud cover in Ecuador yields firm and elastic wrappers while the volcanic soil type in Nicaragua yields wrappers that are less elastic (6).

Lindegaard reported results for a controlled study whereby the same dark air-cured tobacco seed was planted in the same crop year by two different farmers in the same country and local area. A very significant natural variability was quantified including a 379% difference between the arsenic content, 115% difference in N-nitrosonornicotine (NNN) levels, 53% difference in ammonia content, 31% difference in 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) levels, 12% difference in cadmium content and 11% variation in the nicotine content (4).

Lindegaard's findings accentuated the existence of an innate variability within the cigar product due to variations in the tobacco itself. Additionally, Mukoyi et al. advised researchers, investors, leaf merchants, policy makers, and other stakeholders to trade and invest in the viable high-quality cigar wrappers, binders, and filler grown in Zimbabwe. They reported that conditions in the Burma valley area in Zimbabwe, such as ideal loamy to loam-clay well drained soils, high geographical altitude, high ambient relative humidity > 65%, high temperatures (28–35 °C), and high rainfall > 1000 mm/week, promote the growth of pliable fine textured, unique wrapper leaf, which favors the design of premium cigars. They demonstrated that the soil and environment in that precinct are also conducive to performing agronomic germ plasm holistic research to produce a various preeminent shade cloth-cured tobacco leaves capable of resisting foliar diseases like frog eyes, deformations from the scorching sun, droughts and hailstorms (7).

The effect of soil nitrogen content has been shown to impact certain quality attributes of Kentucky dark fire-cured tobacco. Sifola et al. showed that increasing the soil nitrogen impacted the brightness and increased “body” (thickness, density, and weight) of the leaf (8).

Another research group led by Borges performed experiments to establish the optimum nitrogen concentration for percent yield and quality of cigar tobacco based upon leaf chlorophyll content (9). Other researchers have found that nitrogen fertilizer impacted alkali metals like potassium but not alkali earth metals like calcium and magnesium (10). Over a threshold level of nitrogen, however, leaf quality declined rapidly (11) and potassium fertilizers may positively impact yield (12).

Monzón Herrera in collaboration with the University of Hohenheim, Germany, utilized greenhouse (hydroponic and pot farming) techniques to examine the effects of some micronutrients and macronutrients on the development and growth on four Cuban dark tobacco varieties used for “Habanos” cigars. Their extensive study showed that soil types deficient in micronutrients like boron, phosphorus, zinc, magnesium, potassium nitrogen and manganese resulted in various detrimental foliar diseases and defective stem growth patterns in the tobacco plant. They ascertained that the soil nitrogen content strongly impacted the composition of metallic cations in the green tobacco leaf. In conclusion the group advised that (i) early application of nitrogen is needed for intensive vegetative growth of the tobacco plant on landscapes that have compact soils which rarely undergo lixiviation of nitrates, and (ii) for farmers to obtain the best yield and quality harvest the nitrogen content must be increased to about twice the current recommended amount required for soil fertilization (13).

Agricultural practices on cigar tobacco variability

There has been significant research conducted in the area of Crop Protection Agents (CPAs) specifications and application in tobacco farms as well as Good Agricultural Practices (GAP). Vann and Fisher conducted a study on the effects of three CPAs (azoxystrobin, butralin, and flumetralin) on flue-cured tobacco grown in six different areas in North Carolina, USA. The goal of the researchers was to evaluate residue levels of the CPAs in order to administer their proper application rates as well as to determine the minimum preharvest interval application of specific CPAs. They gathered their data based on individual year, individual location, individual CPA, and individual stalk position (lower, middle, and upper) of the tobacco plant. They concluded that although residue concentration of azoxystrobin was quite high compared to butralin and flumetralin, azoxystrobin played a critical role in the control of target spot (Rhizoctonia solani), a foliar disease which was responsible for a 7% yield loss in North Carolina in the 2013 growing season (14).

In 2017 the CORESTA Agro-Chemical Advisory Committee (ACAC) developed and documented various trials performed by different companies across the globe to standardize and mandate specific Cigar Guidance Residue Levels (C-GRLs) for dark air-cured tobacco. Some of the mandates for farmers included strictly controlling fertilization of the soil, proper leaf variety selections, systematic curing strategies, proper topping and suckering as well as optimizing the fermentation process of the cigar leaves. To further bolster the standardization initiative, CORESTA also launched the Agrochemical Residue Field Trials Task Force (RFT-TF) which focused on the development of new agrochemical candidates for setting GRLs in terms of leaf quality and integrity to draw clear distinction between cigar leaf and cigarette tobacco leaves. The task force compared the yields and CPA residues data at different stalk positions between two crop protection programs (the local one, normally based on CPA application relative to when the pathogen is present and the worst-case scenario based on weekly CPA applications), to confirm which was the most effective for eradication of the three main fungal and insect-related tobacco diseases (15).

Design characteristics

Differences in conventional cigarettes typically result from variations in tobacco blends and relatively small variations in cigarette construction and physical dimensions such as length, diameter and pressure drop (16). In the case of cigars, the physical parameters vary greatly within and across product categories. In fact, there are several categories of cigars; each consisting of tobaccos that are unique and different from each other. The two major categories which are premium and machine-made cigars (MMCs) are discussed below.

Premium cigar design characteristics

“Premium”, handmade, hand-rolled, (or long-filler) cigars consist of whole tobacco leaves that, when rolled, run the length of the cigar. Long-filler cigars are of a higher quality than short-filler or medium-filler cigars and tend to burn for a longer time. Most “premium” cigars are made entirely of long-filler tobacco, wrapped in a quality natural tobacco binder and wrapper. Tobacco is sorted, bunched, rolled, molded, and pressed by hand. Finally, the outer wrappers are added. During quality control evaluations, cigars are color matched for packaging (3).

Figure 2 shows a premium cigar design with sections labelled using typical vocabulary while Figure 3 shows the layers/parts of tobacco leaf used for making cigars (17, 18). Typically, the premium cigar body is composed of the wrapper (outer tobacco), binder, and the filler (inner tobacco). Generally, the wrappers are harvested from plants cultivated under shade (shade grown tobacco) whereas the fillers and binders are cultivated under full sunshine (sun grown tobacco). The binders are leaves selected from the lower part of the tobacco stem and should be wide, large, and undamaged as possible. During manufacturing, the binder is rolled around the filler leaves and are together referred to as the bunch. The filler leaves are composed of three proportions or varieties (from bottom to top positions of the stem, respectively) namely, volado (filler itself, which mainly contributes to combustibility), seco (dry, mainly contributes to aroma), and ligero (light, mainly contributes to strength). During the cigar hand rolling formulation process, the ligero leaves are sandwiched between the volado and seco leaves (7, 19). The wrapper leaf which is finally wrapped around the bunch must have excellent pliability and elasticity.

Figure 2

Construction of a typical premium cigar product (17).

Figure 3

Strata, morphology and parts of tobacco leaves used for cigar construction. Colored “stripes” in the diagram represent concentric/rolled layers of tobacco (18).

Figure 4 (a) shows the art of hand-made premium cigars and (b) an ideal cigar wrapper (15). It is reported and putative that the filler contributes about 85% of the total cigar weight, the binder 10%, and the wrapper the remaining 5% (20).

Figure 4

The art of hand-making premium cigars (a). The ideal cigar wrapper after curing in a barn (b) (15).

MMC design characteristics

MMCs cover much more of a range in design complexity and variables compared to premium cigars. The two broad sub-categories are large filter (short-filler) cigars and Medium-Filler cigars. Large filter (or short-filler) cigars are MMCs that consist of chopped up tobacco leaves, which are then rolled into cigars and have a conventional acetate filter applied.

The tobacco in this category of cigars often comes from pieces of the leaf that have been discarded during the process of rolling “premium” or long-filler cigars. Large filter cigars tend to burn hotter and quicker than their long-filler counterparts. By using short-filler tobacco and machines to aid in the cigar rolling process, manufacturers can substantially increase the volume of production relative to a hand-made long-filler cigar.

Medium-filler cigars are MMCs that consist of tobacco leaves, which are chopped into pieces larger than short-filler. Typically, tobacco used in the head and body may differ for an MMC product. These cigars may differ greatly in parameters such as diameter, length, and shape. These variables impact the combustion products, generation of water, variation within cigars, and air flow within the different cigar products.

Due to these broad design variables for both MMCs and hand-made cigars, the standardized smoking regime was developed to maintain a constant airflow through the cigar during machine smoking rather than a constant puff volume as has been specified with standardized cigarette smoking (21).

Cigars and cigarettes comparisons

Much of the recent analytical research for cigars has been designed as a comparison to conventional cigarette results. Some research has been focused on smoking perception but much of the work has been in the area of comparing analytical content and yield or product variability. Two notable differences with regard to cigar smoke are (i) cigar smoke tends to be more alkaline than cigarette smoke and (ii) tobacco commonly used for cigars contains lower levels of reducing sugars than the rapidly dried varieties of tobaccos commonly used in cigarettes. Normal mouth (buccal) saliva is known to be neutral or slightly basic. The impact of the higher alkalinity of cigar smoke (pH 8.5) on nicotine absorption has been studied by Armitage and Turner. The group asserted that because of the higher concentration of unprotonated nicotine in alkaline medium, nicotine in cigar smoke is much more readily absorbed through the buccal mucous membranes than the protonated nicotine in acidic cigarette smoke (pH 5.3) (22). Extensive research by Leffingwell corroborated the complexity and variability in the chemical composition of tobacco leaf types (yellowed, flue-cured, Burley, Oriental, enzyme treated, Virginia, etc.) grown in different parts of the globe (23). They reported that Oriental leaf exclusively contained significant amounts of labdanoid (Z-abienol) and sugar tetraesters, which impact sensory attributes of the Oriental leaf. Quantitative examination of the cuticular tobacco components of cigar leaf and other leaf by Severson and associates outlined striking differences in the levels of analytes such as hydrocarbons, sucrose esters, docosanol and diterpenes (24). Table 1 (adopted from the Tobacco Monograph by Hoffmann and Hoffmann) points out unique chemical composition differences between cigar tobacco and four selected cigarette tobaccos. For example, the table depicts that cigar tobacco contains less than 0.1% polyphenols relative to tobacco blends used for conventional cigarettes (1.6–5.1%) (25). Conversely the cigar nitrate content appears higher than for cigarette tobaccos. Additionally, the burn characteristics of the cigar products differ from conventional cigarettes because cigars typically burn “inside – out” (tunneling) as opposed to the “outside – in” burn characteristics of conventional cigarettes (26). Clearly one would expect that the pyrolysis product profile for cigars will thus differ significantly from that of cigarettes.

Comparison of some selected components in the tobacco of cigars and four cigarette tobacco types (% of dry weight of tobacco) adapted from Hoffmann and Hoffman (25).

Component Cigar Tobacco type used for cigarette

Burley Maryland Bright Oriental
Nitrate 1.4–2.1 1.4–1.7 0.9 <0.15 < 0.1
pH 6.9–7.8 5.2–7.5 5.3–7.0 4.4–5.7 4.9–5.3
Reducing sugars 0.9–2.7 1.5–3.0 1.2 7.0–25.0 5.5
Total polyphenols < 0.1 2.0 1.6 5.1 4.5
Nicotine 0.6–1.7 2.0–2.9 1.1–1.4 1.2–1.9 1.1
Paraffins 0.3–0.32 0.34–0.39 0.34–0.41 0.24–0.28 0.37
Neophytadiene 0.4–0.8 0.4 0.4 0.3 0.2
Phytosterols 0.14–0.16 0.3–0.39 0.38 0.3–0.45 0.26
Citric acid 5.5–6.0 8.22 2.98 0.78 1.03
Oxalic acid 3.3–3.6 3.04 2.79 0.81 3.16
Maleic acid 1.5–1.8 6.75 2.43 2.83 3.87

Table 2 identifies differences between selected volatile components in the smoke of cigars, little cigars, and cigarettes. The concentrations of nitrogen oxides (NOx) are significantly higher in cigar smoke compared to cigarette. This is attributed to the elevated nitrate content of the cigar tobacco, the incomplete combustion, and the naturally low porosity of cigar binders and wrappers (25). In contrast, the ammonia content of cigar smoke is more than three times less than the amount in cigarette smoke. The sources and physical attributes (e.g., full length, filler length, weight, etc.) of the cigars and cigarettes used in the above study are defined in a previous investigation by Hoffmann and Wynder (27).

Components in the gas phase of mainstream smoke of cigars and cigarettes, values are given for 1.0 g tobacco smoked adapted from Hoffmann and Hoffmann (25).

Component Cigars Non-filter cigarettes Little cigars Filter cigarettes
Carbon monoxide (mg) 39.1–64.5 16.3 22.5–44.9 19.1
Carbon dioxide (mg) 121–144 61.9 47.9–97.9 67.8
Nitrogen oxides (NOx) (μg) 159, 300 160 45, 150 90–145
Ammonia (μg) 30.5 95.3 200, 322 98
Hydrogen cyanide (μg) 1,035 595 510, 780 448
Vinyl chloride (ng) n.a. 17.3, 23.5 19.7, 37.4 7.7–19.3
Isoprene (ng) 2750–3950 420, 460 210, 510 132–990
Benzene (μg) 92–246 45, 60 n.a. 8.4–97
Toluene (μg) n.a. 56, 73 n.a. 7.5–112
Pyridine (μg) 49–153 40.5 61.3 27.6, 37.0
2-Picoline, μg 7.9–44.6 15.4 17 14.8, 15.6
3- + 4-Picoline (μg) 17.9–100 36.1 32.9 12.6, 20.2
3-Vinylpyridine (μg) 7.0–42.5 29.1 21.2 102, 192
Acetaldehyde (μg) 1020 960 850, 1390 94.6
Acrolein (μg) 57 130 55, 60 87.6
N ’-Nitrosodimethylamine (ng) n.a. 16.3–96.1 555 7.4
N ’-Nitrosopyrrolidine (μg) n.a. 13.8–50.7 24.5 6.6

n.a.: data not available

Cigar tobacco chemical composition and variability

While testing of cigar smoke is more akin to in-use testing, understanding of tobacco content and variability is an important area of research with significant recent focus. Several studies have focused on fundamental understanding of the leaf. For example, Lauterbach and Grimm extensively investigated the chemistry of cigar wrappers used on MMCs from various brands (28). They identified biomolecules like deoxyfructosazines and fructosazines (sugar-ammonia biomarkers) in the wrappers. They proposed to further study the interactions of the biomarkers and tobacco fillers. In a separate study, Lin et al. observed that the chemical composition of cigar wrappers varied significantly from topping to maturation of the tobacco leaf wrappers. For example, during the first 21 days (from topping to maturation) the ratio of total nitrogen to nicotine decreased constantly whereas the sugar, calcium and magnesium contents increased (29). These results are consistent with composition from topping to maturation of tobaccos used for cigarettes. The effect of curing temperature on the fatty acids profile and ability of amylase and invertase to regulate the carbohydrate content of cigar wrapper leaf has also been reported (30, 31).

On the other hand, many of the recent tobacco studies have focused on understanding content and variability of analytes of regulatory concern. Typically, this is with an underlying objective of determining relevance and feasibility of routine Harmful and Potentially Harmful Constituent (HPHC) testing for this product category.

For example, Lindegaard studied dark air-cured cigar tobacco of the same leaf grade (i.e., same seed, country, local area, texture, color) grown by the same farmer from 2013 to 2015. He noticed significant variability in the composition of ammonia, nicotine, NNN, NNK, arsenic, and cadmium.

It is interesting to note that the difference in nicotine concentration between 2013 and 2014 was 89% whereas the difference in the same analyte between 2014 and 2015 was a nominal 2%. As discussed earlier, this researcher found marked differences in tobacco analyte content in a study wherein the same seed was planted in the same crop year by different near-by farms (4). Wagner et al. also carried out a point-in-time variability study on the smoke and tobacco. With regard to tobacco analysis, the focus of the study was cigarette and smokeless tobacco HPHCs: ammonia, arsenic, cadmium, NNK, NNN, and nicotine. They inferred that for ammonia and nicotine, the %RSD was the same for cigarettes and cigars at approximately 2%. However, for the other analytes, the %RSD of the MMC fillers was twice that of the cigarettes (32). Tayyarah et al. tested different cigar products at multiple laboratories for tobacco HPHCs. The choice of analytes was based on FDA requirements for cigarettes and smokeless tobacco products since there were no specified HPHCs for cigars at the time of the study (33). The design of that study included evaluation of the results to compare range of content and variability between cigars of different design, by laboratories testing cigars from the same lots but using their own methods. The group ensured that participating laboratories were ISO 17025 accredited and used validated methods. With regard to tobacco analytes, there was a clear difference in content for different cigars.

For example, nicotine ranged from approximately 8.3 mg/g to approximately 30 mg/g. However, more interesting findings from the study were that the reported values from the different laboratories for the same samples were in some cases different enough that, in a blind study, one may conclude the results were from different samples. For example, for Sample F, the tobacco NNN values reported by Laboratory 1 and Laboratory 3 were in a similar range at 1748 ng/g and 2050 ng/g, respectively. Laboratory 2 reported a value of 4497 ng/g for the same sample batch, which was more than twice that of the other labs. The differences in standard deviation of the nicotine values between the laboratories were particularly conspicuous with %RSD values of 0.8%, 14%, and 4% for Laboratory 1, 2, and 3, respectively. This supports the essence of current initiatives to increase standardization of testing, including a validated, internationally recognized methodology. Other reported studies on tobacco constituents are consistent with these findings. They include investigations by Koszowski et al. wherein they described extensive variability of the nicotine content and physical dimensions of cigars and cigarillos in the cigar market (34). This substantive difference in cigars has been studied and confirmed by other research groups (35, 36, 37, 38).

Physical parameters as a measure of inherent product variability

Some researchers have focused attention on physical parameters as a direct and practical measure of product variability. Testing for weight and length is relatively inexpensive with high throughput and low measurement variability.

Testing for diameter and pressure drop may be less reliable given the range of product designs and lack of standardization for measurement technology; it is advisable to limit comparisons of results for these measures between products of different design and/or between laboratories using different analytical methodology.

Wagner et al. found striking differences in magnitude of weight and pressure drop (referred to as resistance to draw in their work) when comparing a set of 10 hand-made cigars, 77 machine-made cigars, and 10 typical cigarettes. The researchers found that the relative weight of 100 replicates varied as much as 48% for hand-made products and 70% for machine-made products in the study but was typically less than a 14% spread for cigarettes (39). Teillet, Vernon and Colard presented findings from a study of diameter, length, weight, and pressure drop for hand-made cigars. Teillet reported low variability for direct control measures (length and diameter). However, measures not directly controlled during the hand-making process had point-in-time %RSDs of 40% (weight) and 120% (pressure drop) (40). The findings highlighted in this review are supported by additional studies conducted by other researchers (41, 42, 43).

Cigar smoke chemical composition and variability

There is a rich body of literature, inter-laboratory studies, and significant hands-on experience for testing constituents of conventional cigarettes. For example, standard validated ISO methods for analyses of polyaromatic hydrocarbons (PAHs) tobacco-specific nitrosamines (TSNAs), polyaromatic amines (PAAs), ammonia, chlorides, volatile organic compounds (VOCs), “tar”, nicotine, and carbon monoxide (TNCO) and metals in conventional cigarette smoke are well-documented, established across the tobacco industry, and in use in ISO-accredited third party labs. In addition, several cigarette smoking regimes (ISO, HCI, Massachusetts, CORESTA) and cigarette references have been established, beginning as early as the 1960s (44). In contrast, expertise and standardization with cigar HPHCs testing is substantially limited. For instance, there is a standardized puffing regime and handling requirements (described in CORESTA Recommended Methods (CRM) 64 and 65) (21, 45), but application of that regime to cigars for constituents beyond “tar”, nicotine, and carbon monoxide (TNCO) methods needs optimization for both method development and testing consistency across labs. Within the past decade, study designs, presentations, and publications have revealed the challenges encountered and strides achieved in cigar testing method development. The challenges include optimization of smoke holder accessories needed to accommodate different cigar sizes, lack of in-house method development for cigar analysis and inter-lab proficiency studies for both MMC and premium cigar products.

Recent reports related to analytical testing of cigar smoke have focused on understanding yield differences across the product category, often in comparison to conventional cigarettes, inherent variability of smoke analytes, and challenges with regard to smoking parameters and technology.

Wagner et al. presented results for a TPM (total particulate matter) comparison between cigarettes and machine-made cigars smoked under standard regimes. The cigarettes were smoked using the standard regimes (ISO, HC (Intense)) and the cigars were smoked using the cigar smoking CRMs referenced herein. The holder used for cigar smoking, an ALCS smoke trap, was a custom design (39). Figure 5 presents a striking example with the simplest smoking measurement (the weight of trapped particulates), to support observations of inherent product variability and the challenges of machine-smoking cigar products (39). It can be inferred from Figure 5 that the variability in TPM of the cigars was substantially higher than the two cigarette regimes. While the cigarette ISO and HCI smoking regimes yielded approximately 5–25% and 30–70% TPM variability respectively, the cigar variability was 40–120% which was over 70% higher than that of the cigarettes. In another study, Tayyarah et al. compared mainstream cigarette smoke analytes tested in different laboratories using their own in-house methods. The analytes under study were HPHCs typically performed on cigarettes such as carbon monoxide, smoke nicotine, selected carbonyls, VOCs, tobacco nicotine, tobacco ammonia, TSNAs, PAAs, and PAHs (33). Despite the fact that all the labs were ISO 17025 accredited and used properly validated methods, their conclusions were similar to most findings for tobacco analytes i.e., the analyte levels varied greatly between samples and between reported results from different laboratories testing the same product lots.

Figure 5

TPM variability comparison for 146 commercial cigarette products and 86 commercial cigar products under different smoking regimes, n = 55 (39).

Wagner et al. (32) also carried out a short-term variability study on the smoke and filler of 24 MMCs and 146 cigarettes products. They compared the variability between MMCs and cigarettes of 19 selected HPHCs under ISO, Intense and CORESTA smoking regimes. Their results affirmed that, under a specific smoke regime, variability between each quantified analyte was about 5–20% more pronounced in cigars than in cigarettes. For example, under ISO, the average %RSD of NNK for cigars was approximately 22% relative to about 5% for cigarettes. Similarly, under ISO Intense, the average %RSD of formaldehyde was 20% for cigars and about 8% for cigarettes.

For cigars, the CORESTA regime produced the highest HPHC variability while the ISO regime recorded the highest HPHCs variability amongst cigarettes.

Young et al. also investigated the extent of chemical composition and weight variations within some selected small (SM), large (LG), and sheet-wrapped (SW) cigar products under the CRM 64 guidelines. Their results in Table 3 summarize the changes in the mean %RSD that occurred in the carbonyl yields from 2016–2017. The values indicated represent the analytes that showed statistically significant differences between 2016 and 2017. For example, in 2016 the mean %RSD of formalde-hyde for Phillies Blunt (LG) was 9.6 and increased to 19.8 in 2017. This computes to a notable mean formaldehyde yield %RSD difference of about 106% within a year. Even products of similar size that were tested in the same year showed a wide range of %RSD values in parenthesis. They inferred that since no certified/qualified cigar reference was available to be used as a control, they could not confidently attribute the relative %RSD values to either the inter-sample or method variability (46).

Carbonyl yields in cigarillo and leaf-wrapped cigar products tested in 2016 and 2017 under CRM 64 smoking regimen (n = 7) adapted from Young et al. (46).

Tobacco Product Brand Name 2016-Carbonyl yields, mean (RSD) 2017-Carbonyl yields, mean (RSD)


Tobacco product weight (mg/unit) Form-aldehyde (μg/unit) Acet-aldehyde (μg/unit) Acrolein (μg/unit) Tobacco product weight (mg/unit) Form-aldehyde (μg/unit) Acet-aldehyde (μg/unit) Acrolein (μg/unit)
Cheyenne Cigarillo Dark & Mellow (SM) 2462 (6) 11.6 (16) 1015 (8) 20.2 (22) 2688 (4) 8.9 (12) a 1246 (16) a 14.2 (54)
Cheyenne Cigarillo Dark & Sweet (SM) 2354 (8) 10.2 (14) 1258 (12) 21.8 (21) 2806 (3) 9.8 (20) 1333 (13) 16.2 (25) a
Dutch Masters Cigarillo (SM) 2484 (9) 16.7 (34) 2232 (9) 46.2 (30) 2879 (9) 9.8 (16) a 2259 (23) 23.1 (32) a
Game - Black (SM) 2161 (8) 16.3 (25) 1681 (10) 33 (22) 2363 (6) 12.1 (22) a 1817 (14) 30.8 (30)
Swisher Sweet Cigarillos - Sticky Sweet (SM) 2277 (5) 13.1 (11) 1551 (11) 33.6 (18) 2794 (2) 10.7 (17) a 1571 (19) 22.5 (41) a
Swisher Sweet Cigarillos (SM) 3048 (14) 16.1 (19) 1926 (10) 15 (43) 2682 (3) 12.9 (22) 1889 (15) 36.2 (31) a
Swisher Sweet Cigarillos - Black (SW) 2457 (3) 9.8 (24) 1548 (9) 25.7 (36) 2676 (3) 9.3 (18) 1799 (31) 20.7 (55)
Dutch Masters President (LG) 7538 (3) 11.8 (12) 4855 (7) 49 (16) 7603 (5) 16.3 (9) a 3913 (17) a 34.5 (22) a
Phillies Blunt (LG) 6611 (6) 9.6 (15) 3152 (4) 35.8 (25) 6931 (4) 19.8 (18) a 4145 (20) a 64.6 (33) a

Diameter at 15 mm: SM = 9–10.5 mm, SW ≤ 8 mm, LG = 15–16.5 mm

indicates statistically different constituent yield for the tobacco product analyzed in 2016 and 2017 (p < 0.05)

Curing, pre-processing, aging and sampling on cigar tobacco variability

The variability of tobacco-specific nitrosamines (TSNAs) which occurs during flue-curing and air-curing of cigar dark tobacco has been a contentious public health debate and well-studied. Cultivation of dark air-cured requires high quantity of fertilizers in nitrate NO3 form, which produces high concentration of this polyatomic anion in cured leaves. According to BUSH and coworkers, during curing the aerobic conditions cause the reduction of the nitrates to nitrites (NO2) which then react with the secondary alkaloids within the tobacco leaf to form the TSNAs (47). Richmond et al. studied the correlation between curing environment and TSNA accumulation in two barns about 200 miles apart. They found that although barn curing conditions like temperature and relative humidity impacted concentration of TSNAs, other crucial factors like the barn construction, inconsistency in microenvironments within the same barn and improper positioning of data loggers (which records/monitors the temperature and humidity) could also introduce more TSNA variability (48). Thus the impact of curing on analyte variability is an important consideration.

Another source of variability within this product category is sampling. The significance of monitoring analytes in cigar tobacco via product sampling and sample size considerations cannot be overemphasized. Borges Miranda et al. performed extensive characterizations of both raw materials and cigar products to underscore the inconsistencies of tobacco blends used for premium cigars as well as the variability that arises from different testing methodologies and analytes. In 2019, the group utilized the near-infrared-reflectance-spectroscopic technique to characterize 322 powdered samples (raw materials and products) of dark air-cured Cuban cigar tobacco that were processed the same way (19). Their study revealed significant statistical differences between the total alkaloids-nicotine, total nitrogen, and total ash concentration in the cigar tobacco. They processed the spectra and evaluated the variability of these analytes with several statistical regression models such as the PLS, PCR, and MLR models and ascertained that the PLS model exhibited better reproducibility, precision, and prediction statistics. To enhance standardization and mitigate some of the variability in premium cigar tobacco, the group recently analyzed about 3780 different cigars and proposed a chemosensory technique and methodology for selecting raw materials from specific lots and optimizing the aging time required for processed tobacco leaves. Their study also identified specific chemical constituents and independent variables in the raw materials that could be analyzed and used as indexes of the cigar strength (49). Borges Miranda et al. have once again reported that it is consequential to sample raw materials at the end of the stripping workshop, which is the phase where the low-quality leaves are separated from the production line for premium cigars. The group utilized a randomized sampling design and three estimation errors (difference between sample mean and actual population mean) to measure the nicotine content of different batches of tobacco produced in different geographical precincts. They concluded that although about 2016 samples a year could be analyzed (with an estimation error of 0.2 % w/w), the sample count should be increased to include and account for leaves pre-processed daily during the pre-processing season (50).

Odelin and Borges Miranda also inferred that the weight of cigars had a substantial influence on the concentration of the smoke analytes; and determined the minimal sample size required to estimate the weight of a single premium cigar (51). It is worth noting that CORESTA has embarked on crucial studies as part of international standardization efforts to address the TSNA variability and sampling predicament (52, 53). Other researchers have focused on agronomic and germplasm studies as means to standardize, optimize and homogenize the cigar leaf composition at the end of preprocessing to help minimize variability. In this regard, Morán Gómez et al. investigated the correlation between bacteria genera population density, the pH and nicotine concentration in cured tobacco leaves harvested from different locations of the stalk/stem. They identified and isolated bacterial microbiota such as Staphylococcus, Arthrobacter genus and the Bacillus genus. They found that although the Staphylococcus and Arthrobacter species are important indicators, the Bacillus genera were the most predominant in the leaves processed from all stalk positions. They also inferred that the bacteria population density was more dependent on the leaf nicotine levels than the changes in pH values. The group further emphasized that genomic technology could reduce the processing time of tobacco leaves, improve the quality of lower grade leaves, and ultimately promote a more homogeneous composition of the leaves at the end of pre-processing (54). Ye et al. conducted a similar study using genetic sequencing to identify beneficial microbial strains which could improve the quality of the cigar products (specifically the aging process of the cigar product itself) and hence reduce the end-product variability. Their study revealed quite a significant diversity of fungi and bacteria strains in ten different cigar products. The predominant bacterial genera were Staphylococcus, Acinetobacter, and Pseudomonas while that of the fungal genera was Aspergillus (55).

ANALYTICAL METHODS DEVELOPMENT AND STANDARDIZATION EFFORTS

Several researchers have reported findings that shed light on the challenges of analytical cigar smoking. These include conditioning protocols for cigar products, the effects of lighting technique on smoke constituents, number of relights, effects of ash removal, and the complexity of choosing a proper cigar holder (56, 57, 58).

Continued refinement and extension of standard analytical methods and techniques along with establishment of reference products is the primary response to these challenges (21, 45). Specific analytical methods and validation protocols for cigars need to be developed. Listed in Table 4 are a summary of results for several studies which focused on testing of constituents in cigar tobacco leaf and smoke which could be adopted or further developed (59, 60, 61, 62, 63, 64, 65). Several researchers have investigated the feasibility of extension of cigarette smoking methods for use with cigars, but this work has only confirmed the need for cigar-specific smoking methods. For example, the CORESTA Tobacco and Tobacco Products Analysis (TTPA) and Smoke Analysis (SA) Sub-groups have formally taken this as a primary approach to CRM development (66). Prepelitskaya et al. investigated the feasibility of analyzing the ammonia content of cigars using the already standardized CRM 83 “Determination of Ammonia in Mainstream Cigarette Smoke by Ion Chromatography” for testing cigarettes. Their findings indicated that specialized methods needed to be developed for the analysis of ammonia in cigar smoke as the CRM 83 method had shortcomings when applied to cigars (67). Brooks presented a method for volatile organics in cigar smoke using a modification of an existing in-house method for cigarettes (68). Separately, Jablonski et al. and Ballentine et al. took a similar approach to developing a smoke carbonyls analytical method for cigars (36, 69).

Selected analytical methods previously applied to testing of cigar leaf and cigar smoke constituents.

Sample analyzed Constituent and method of determination Method feasibility with existing equipment Detection limit
Tobacco (1.0 g) from cigarettes was placed into a 20-mL head-space vial. Internal standard solution (2 μL of 1 μg/μL 2,6-dichlorotoluene) and flavor spike mixture (1 μL of 1 μg/μL each benzaldehyde, tetra-methylpyrazine, methanol, and anethole in ethanol) were added. The samples were sealed and allowed to equilibrate for 2 h at room temperature before analysis (59) Flavor additives to tobacco (e.g., menthol, anethole, benzaldehyde, and tetramethylpyrazine)Headspace solid-phase microextraction-gas chromatographymass spectroscopy (HS-SPME-GCMS) for both qualitative and quantitative analysis) Feasible but could be very tedious, time consuming & unproductive Benzaldehyde = 66 ng/gmethanol = 120 ng/ganethole = 16 ng/gtetramethylpyrazine = 163 ng/gacetophenone = 41 ng/g
10.0 g tobacco sample was added to 40 ml dichloromethane. Then the mixture was shaken overnight and steam distillated for 3 h to obtain 800 mL aqueous solution of volatile components using a simple apparatus (60) Lactones, benzaldehyde, 6-methyl-2-heptanone, 2,4-dimethyl-1-penten-3-one, etc.Steam distillation (SD), simultaneous distillation and extraction (SDE) and headspace co-distillation (HCD)-GC-MS utilized for all volatiles Feasible but could be very tedious, time consuming & unproductive Total detected 315.72–445.48 μg/g
Evaluation of volatiles from flue-cured tobacco varieties, smoke organoleptic (61) Lactones, benzaldehyde, 6-methyl-5-hepten-2-one, etc.Steam distillation of 10 g tobacco, capillary GC/GC-MS Distillation system must be available 200–600 μg/g
Smokeless tobacco products including snuff, plug tobacco, chewing tobacco, pellets, and snus (62) α- and β-angelica lactonesHeadspace gas chromatography mass spectrometry (HS-GC-MS) Feasible. However, reference standards for β-angelica lactone unavailable or difficult to obtain The limit of detection was 30 ng/g and limit of quantitation 65 ng/g with a variability of 9–44% (RSD)
Tobacco samples used for analysis were Brazilian flue-cured, Kentucky Burley, N. rustica, and Greek and a sample of commercially available roasted peanuts (63) Benzaldehyde, 6-methyl-5-hepten-2-one, acetone, hexenal Chromatography-mass selective detection-flame ionization detection (PT-GC-MSD-FID) hyphenated technique with purge-and-trap-gas Feasible with little modification Semiquantitative and qualitative analysis
Qualitative and quantitative analysis was developed and validated for volatile flavour components in flue-cured tobacco (64) Flavour components in flue-cured tobacco (e.g., pyridine, 6-methyl-5-hepten-2-one, benzene acetaldehyde, benzaldehyde, furfural)HS-SPME followed by GC × GC-TOF-MS Feasible but must have TOF-MS on scope 5.7–147.6 ng/g
Determination of selective phenolic compounds in cigarette and MMC cigar smoke (65) Phenolics (e.g. hydroquinone, resorcinol, phenol, catechol, and o-, m-, and p-cresol).Ultra-high pressure liquid chromatography (UHPLC) and fluorescence detector (FLD) with a sub-2 μm pentafluoro-phenylpropyl phase analytical column Feasible high throughput method that is based on CRM 78, which has a run time of 10 minutes Quantitative and qualitative analysis

Studies are currently underway to evaluate cigar tobacco leaves and smoke tested for HPHCs typically applied to cigarette and/or smokeless tobacco testing like carbon monoxide analysis, smoke nicotine, selected carbonyls, VOCs, tobacco nicotine, tobacco ammonia, TSNAs, PAAs, and polyaromatic hydrocarbons. A typical example is CORESTA Project 198 which is a collaborative study to analyze BaPs and TSNAs in cigar smoke (70). For smoke measurements, CORESTA recommended and ISO methods for conditioning, smoke collection, and TNCO analysis of cigar tobacco products as described in CRM 64 and CRM 65 have been employed. Details from these analyses, along with information regarding challenges associated with testing across a range of cigars have fairly been investigated.

Cigar reference products

Another concern is that although there is availability of multiple reference cigarettes, internationally approved cigar testing/smoking references or monitors have not been established.

Fortunately, a project led by an industry team and the University of Kentucky in collaboration with CORESTA and accredited tobacco testing facilities to develop cigar monitors/references was completed in 2019 to fill this gap. A set of reference products, described in Table 5, were formulated with different tobacco composite blends and with varying design features that can represent most of the cigar shapes and sizes (71). The university has developed and marketed several tobacco references, including RT6, a flavored cigar ground filler, and RT8, an unflavored cigar ground filler (72). The University of Kentucky was recently awarded a U.S. federal grant to develop a set of certified reference products (73). Nonetheless, until this project is completed, gaps will exist in the literature for the definitive comparison of physiochemical composition of cigar tobacco leaf and smoke constituents. Additional studies related to analysis of cigar smoke in the recent past include work by Dethloff et al. and Mueller and Colard, among others (74, 75, 76, 77, 78).

Cigar reference products available through the University of Kentucky (72).

Reference cigar Product type Cigar diameter (mm) Cigar length (mm)
1C1 Large machine-made cigar 15.9 136.5
1C2 Machine-made filtered cigar 7.8 99.0
1C3 Small machine-made cigarillo 11.0 109.5
1C4 Large machine-made natural wrapper 12.8 103.0
REGULATION

World-wide tobacco regulation is in various stages of implementation along different strategic pathways. Typically, cigars represent a small fraction of a country's tobacco market and have been a much lower priority for regulatory actions than cigarettes. In most countries that have implemented regulations, the focus has been on physical measurements, ingredient and marketing reports. In the USA, the FDA has taken an approach similar, though delayed, to the approach taken for cigarettes. FDA regulation of cigarettes and smokeless tobacco products began in 2009 (79). Over time, an expanded list of recommended HPHCs for those products has been established. As previously noted, in 2016, the FDA published a Final Deeming Rule extending its regulatory scope under the Tobacco Control Act to all other tobacco products, including cigars (80).

Once FDA publishes final guidance relating to HPHC testing, the Final Deeming Rule as written will require stand-alone HPHC testing data for cigars. While stand-alone testing may be required for these products under the Tobacco Control Act, the challenges discussed herein related to the variability inherent to cigars make testing for comparative purposes unreliable. Accordingly, researchers consistently urge caution against use of any such analytical testing data as metrics for product comparisons in the context of substantial equivalence review.

For instance, with regard to HPHC testing, LONG recently enumerated the challenges associated with the proposed FDA objective to use HPHC data as an analytical rubric to determine the substantial equivalence (SE) for cigars. He elaborated on an extensive study carried out by Tabacalera USA (TUSA) using 91 premium cigars of 43 different sizes and 18 different blends of dark air-cured tobacco, wherein they inferred that almost all the 36,000 data points generated were statistically misleading, inconclusive and disclosed the immeasurable variability that existed even between cigars of the same size as well as cigars made from the same tobacco composite blends (81). In general, researchers emphasized that, based on the relatively high inherent variability of many analytes with unknown factors, it is advisable to avoid cigar comparisons using HPHC testing (4, 81).

ON-GOING CHALLENGES AND ACTIVE OPPORTUNITIES

First and foremost, researchers and regulators must understand that there are certain challenges with this product category that will always be a consideration for study design, data analysis, and evaluation of data across the product category. The inherent variability of cigar tobacco due to uncontrollable agricultural considerations, along with variability of the seed genome, and product construction cannot be mitigated with analytical controls or method standardization. That said, there are many active and potential opportunities in this area of testing.

For example:

Establishment of ISO standardized analytical methodologies for appropriate measures and analyses to properly characterize cigars and cigar smoke across the spectra of designs,

Full characterization and consistent use of recent and pending reference cigars and cigar tobaccos for surrogate characterization studies, aging studies, and method or laboratory comparisons,

Increasing standardization with regard to smoking equipment, physical parameter measurement requirements, cutting and measurement standards, lighting and relighting techniques,

Continued evaluation of the approach for collecting mainstream smoke as applied to all cigar categories to account for the significant differences in design parameters. For example, design parameters like circumference, length, mouthpiece-type, diameter determination of cylindrical vs. non-cylindrical products, ventilation, and raw components vary significantly across the portfolio of cigar products,

Improvements to conditioning and storage requirements to allow greater consistency between laboratories, and

Establishment of data reporting norms that allow for consistent data analysis across the product category.

To address the challenges above, several approaches have been undertaken, or are currently underway. In the absence of standardized testing specific for cigars, several contract testing laboratories have chosen to incorporate in-house developed cigar methods into the scope of their ISO 17025 accredited methodologies for tobacco product testing. The salient risk in these scenarios would be how to track cigar testing as well as how to account for inter- and intra-laboratory data/report reproducibility or uncertainties over time. Within CORESTA, several active working groups are addressing these challenges for all cigar products. The CORESTA active working groups acknowledge that there are many different types of cigars and that one testing methodology will not be appropriate for all cigar products. For example, the CORESTA Cigar Smoking Methods Subgroup is currently documenting and publishing the technical reports and technical guidelines associated with the TNCO testing of a variety of cigar products (82). In addition, three CORESTA Recommended Methods (CRMs 46, 64, and 65) for conditioning and collection of smoke from cigars have been revised to more accurately reflect technology capabilities and applicability to a wider range of cigar products (21, 45, 83). Further, a CORESTA project to specifically address challenges for testing handmade long-filler cigars has recently been concluded. Lastly, the CORESTA SA Sub-group and the TTPA Sub-group are both actively seeking opportunities to include cigars in inter-laboratory proficiency studies as capabilities to enable standardized and uniform testing across all laboratories. The TTPA Sub-group has brought cigars into scope for nine tobacco methods with additional methods expansions in progress (84). The SA Sub-group has recently completed its first joint experiment for cigar smoke constituents and has established a long-term plan for cigar CRM development (85). The University of Kentucky has established plans to expand the scope of their proficiency testing program to include cigar testing (71, 73)

CONCLUSIONS

This review provides a summary of recent analytical research in the area of cigar testing. Undeniably, relative to cigarettes, there is much less research on cigars, hence challenges envisaged with analytical testing of cigars remain to be addressed thoroughly. Especially with regard to the substantial variety between same cigars and cigars of different brands as well as tobacco leaves of different origin, year of harvest and/or method of cultivation. However, there is consistency in the findings reported herein, which underscores the fact that cigars have a very high inherent variability which leads to a very wide range of agricultural yields.

There has been significant on-going activity with regard to cooperative methods of development and standardization. Recent successes in this area have included establishment of a set of reference cigars, establishment of guidance for hand-made cigar testing, and strategies for expansion of scope for standard or accepted methodology specific to cigars. With regard to regulatory oversight, researchers recommend against using HPHC testing for product regulation, comparison, and characterization due to the high inter- and intra-product variability. Physical parameters and ingredient reports seem most practical metrics for product comparison given the high complexity and inherent variability of the product category along with the relatively immature foundation of analytical standardization.

While the studies reviewed in this manuscript highlight an increase in the volume of research associated with cigar testing, additional standardization and cooperative testing is needed to establish a true foundation of analytical understanding of this product category.

Figure 1

Statistical hierarchy of review method findings based on (a) general tobacco literature search and (b) cigar science literature search for about 1100 peer reviewed publications.
Statistical hierarchy of review method findings based on (a) general tobacco literature search and (b) cigar science literature search for about 1100 peer reviewed publications.

Figure 2

Construction of a typical premium cigar product (17).
Construction of a typical premium cigar product (17).

Figure 3

Strata, morphology and parts of tobacco leaves used for cigar construction. Colored “stripes” in the diagram represent concentric/rolled layers of tobacco (18).
Strata, morphology and parts of tobacco leaves used for cigar construction. Colored “stripes” in the diagram represent concentric/rolled layers of tobacco (18).

Figure 4

The art of hand-making premium cigars (a). The ideal cigar wrapper after curing in a barn (b) (15).
The art of hand-making premium cigars (a). The ideal cigar wrapper after curing in a barn (b) (15).

Figure 5

TPM variability comparison for 146 commercial cigarette products and 86 commercial cigar products under different smoking regimes, n = 55 (39).
TPM variability comparison for 146 commercial cigarette products and 86 commercial cigar products under different smoking regimes, n = 55 (39).

Comparison of some selected components in the tobacco of cigars and four cigarette tobacco types (% of dry weight of tobacco) adapted from Hoffmann and Hoffman (25).

Component Cigar Tobacco type used for cigarette

Burley Maryland Bright Oriental
Nitrate 1.4–2.1 1.4–1.7 0.9 <0.15 < 0.1
pH 6.9–7.8 5.2–7.5 5.3–7.0 4.4–5.7 4.9–5.3
Reducing sugars 0.9–2.7 1.5–3.0 1.2 7.0–25.0 5.5
Total polyphenols < 0.1 2.0 1.6 5.1 4.5
Nicotine 0.6–1.7 2.0–2.9 1.1–1.4 1.2–1.9 1.1
Paraffins 0.3–0.32 0.34–0.39 0.34–0.41 0.24–0.28 0.37
Neophytadiene 0.4–0.8 0.4 0.4 0.3 0.2
Phytosterols 0.14–0.16 0.3–0.39 0.38 0.3–0.45 0.26
Citric acid 5.5–6.0 8.22 2.98 0.78 1.03
Oxalic acid 3.3–3.6 3.04 2.79 0.81 3.16
Maleic acid 1.5–1.8 6.75 2.43 2.83 3.87

Components in the gas phase of mainstream smoke of cigars and cigarettes, values are given for 1.0 g tobacco smoked adapted from Hoffmann and Hoffmann (25).

Component Cigars Non-filter cigarettes Little cigars Filter cigarettes
Carbon monoxide (mg) 39.1–64.5 16.3 22.5–44.9 19.1
Carbon dioxide (mg) 121–144 61.9 47.9–97.9 67.8
Nitrogen oxides (NOx) (μg) 159, 300 160 45, 150 90–145
Ammonia (μg) 30.5 95.3 200, 322 98
Hydrogen cyanide (μg) 1,035 595 510, 780 448
Vinyl chloride (ng) n.a. 17.3, 23.5 19.7, 37.4 7.7–19.3
Isoprene (ng) 2750–3950 420, 460 210, 510 132–990
Benzene (μg) 92–246 45, 60 n.a. 8.4–97
Toluene (μg) n.a. 56, 73 n.a. 7.5–112
Pyridine (μg) 49–153 40.5 61.3 27.6, 37.0
2-Picoline, μg 7.9–44.6 15.4 17 14.8, 15.6
3- + 4-Picoline (μg) 17.9–100 36.1 32.9 12.6, 20.2
3-Vinylpyridine (μg) 7.0–42.5 29.1 21.2 102, 192
Acetaldehyde (μg) 1020 960 850, 1390 94.6
Acrolein (μg) 57 130 55, 60 87.6
N ’-Nitrosodimethylamine (ng) n.a. 16.3–96.1 555 7.4
N ’-Nitrosopyrrolidine (μg) n.a. 13.8–50.7 24.5 6.6

Selected analytical methods previously applied to testing of cigar leaf and cigar smoke constituents.

Sample analyzed Constituent and method of determination Method feasibility with existing equipment Detection limit
Tobacco (1.0 g) from cigarettes was placed into a 20-mL head-space vial. Internal standard solution (2 μL of 1 μg/μL 2,6-dichlorotoluene) and flavor spike mixture (1 μL of 1 μg/μL each benzaldehyde, tetra-methylpyrazine, methanol, and anethole in ethanol) were added. The samples were sealed and allowed to equilibrate for 2 h at room temperature before analysis (59) Flavor additives to tobacco (e.g., menthol, anethole, benzaldehyde, and tetramethylpyrazine)Headspace solid-phase microextraction-gas chromatographymass spectroscopy (HS-SPME-GCMS) for both qualitative and quantitative analysis) Feasible but could be very tedious, time consuming & unproductive Benzaldehyde = 66 ng/gmethanol = 120 ng/ganethole = 16 ng/gtetramethylpyrazine = 163 ng/gacetophenone = 41 ng/g
10.0 g tobacco sample was added to 40 ml dichloromethane. Then the mixture was shaken overnight and steam distillated for 3 h to obtain 800 mL aqueous solution of volatile components using a simple apparatus (60) Lactones, benzaldehyde, 6-methyl-2-heptanone, 2,4-dimethyl-1-penten-3-one, etc.Steam distillation (SD), simultaneous distillation and extraction (SDE) and headspace co-distillation (HCD)-GC-MS utilized for all volatiles Feasible but could be very tedious, time consuming & unproductive Total detected 315.72–445.48 μg/g
Evaluation of volatiles from flue-cured tobacco varieties, smoke organoleptic (61) Lactones, benzaldehyde, 6-methyl-5-hepten-2-one, etc.Steam distillation of 10 g tobacco, capillary GC/GC-MS Distillation system must be available 200–600 μg/g
Smokeless tobacco products including snuff, plug tobacco, chewing tobacco, pellets, and snus (62) α- and β-angelica lactonesHeadspace gas chromatography mass spectrometry (HS-GC-MS) Feasible. However, reference standards for β-angelica lactone unavailable or difficult to obtain The limit of detection was 30 ng/g and limit of quantitation 65 ng/g with a variability of 9–44% (RSD)
Tobacco samples used for analysis were Brazilian flue-cured, Kentucky Burley, N. rustica, and Greek and a sample of commercially available roasted peanuts (63) Benzaldehyde, 6-methyl-5-hepten-2-one, acetone, hexenal Chromatography-mass selective detection-flame ionization detection (PT-GC-MSD-FID) hyphenated technique with purge-and-trap-gas Feasible with little modification Semiquantitative and qualitative analysis
Qualitative and quantitative analysis was developed and validated for volatile flavour components in flue-cured tobacco (64) Flavour components in flue-cured tobacco (e.g., pyridine, 6-methyl-5-hepten-2-one, benzene acetaldehyde, benzaldehyde, furfural)HS-SPME followed by GC × GC-TOF-MS Feasible but must have TOF-MS on scope 5.7–147.6 ng/g
Determination of selective phenolic compounds in cigarette and MMC cigar smoke (65) Phenolics (e.g. hydroquinone, resorcinol, phenol, catechol, and o-, m-, and p-cresol).Ultra-high pressure liquid chromatography (UHPLC) and fluorescence detector (FLD) with a sub-2 μm pentafluoro-phenylpropyl phase analytical column Feasible high throughput method that is based on CRM 78, which has a run time of 10 minutes Quantitative and qualitative analysis

Cigar reference products available through the University of Kentucky (72).

Reference cigar Product type Cigar diameter (mm) Cigar length (mm)
1C1 Large machine-made cigar 15.9 136.5
1C2 Machine-made filtered cigar 7.8 99.0
1C3 Small machine-made cigarillo 11.0 109.5
1C4 Large machine-made natural wrapper 12.8 103.0

Carbonyl yields in cigarillo and leaf-wrapped cigar products tested in 2016 and 2017 under CRM 64 smoking regimen (n = 7) adapted from Young et al. (46).

Tobacco Product Brand Name 2016-Carbonyl yields, mean (RSD) 2017-Carbonyl yields, mean (RSD)


Tobacco product weight (mg/unit) Form-aldehyde (μg/unit) Acet-aldehyde (μg/unit) Acrolein (μg/unit) Tobacco product weight (mg/unit) Form-aldehyde (μg/unit) Acet-aldehyde (μg/unit) Acrolein (μg/unit)
Cheyenne Cigarillo Dark & Mellow (SM) 2462 (6) 11.6 (16) 1015 (8) 20.2 (22) 2688 (4) 8.9 (12) a 1246 (16) a 14.2 (54)
Cheyenne Cigarillo Dark & Sweet (SM) 2354 (8) 10.2 (14) 1258 (12) 21.8 (21) 2806 (3) 9.8 (20) 1333 (13) 16.2 (25) a
Dutch Masters Cigarillo (SM) 2484 (9) 16.7 (34) 2232 (9) 46.2 (30) 2879 (9) 9.8 (16) a 2259 (23) 23.1 (32) a
Game - Black (SM) 2161 (8) 16.3 (25) 1681 (10) 33 (22) 2363 (6) 12.1 (22) a 1817 (14) 30.8 (30)
Swisher Sweet Cigarillos - Sticky Sweet (SM) 2277 (5) 13.1 (11) 1551 (11) 33.6 (18) 2794 (2) 10.7 (17) a 1571 (19) 22.5 (41) a
Swisher Sweet Cigarillos (SM) 3048 (14) 16.1 (19) 1926 (10) 15 (43) 2682 (3) 12.9 (22) 1889 (15) 36.2 (31) a
Swisher Sweet Cigarillos - Black (SW) 2457 (3) 9.8 (24) 1548 (9) 25.7 (36) 2676 (3) 9.3 (18) 1799 (31) 20.7 (55)
Dutch Masters President (LG) 7538 (3) 11.8 (12) 4855 (7) 49 (16) 7603 (5) 16.3 (9) a 3913 (17) a 34.5 (22) a
Phillies Blunt (LG) 6611 (6) 9.6 (15) 3152 (4) 35.8 (25) 6931 (4) 19.8 (18) a 4145 (20) a 64.6 (33) a

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