Identifying VOCs Influencing Tobacco Fermentation Quality Using GC and E-nose

A recent study (1) has highlighted the important role of volatile organic compounds (VOCs) in shaping the flavor profile of filler tobacco leaves (FTLs). Past studies have suggested that FTLs are the core of a cigar (2), making them a key component in cigar production, particularly in hand-rolled cigars.

Brown cigar on grey background | Image Credit: © Aiina - stock.adobe.com

The tobacco industry is big business, generating billions of dollars in revenue all around the world (3). According to the Word Health Organization (WHO), there are estimated to be 1.25 billion adult tobacco users around the world (4). Numbers of tobacco users have fallen globally, with 1 in 5 adults consuming tobacco in 2022 against 1 in 3 in 2000 (5). The number of cigarette smokers has declined in line with this; however, the smoking of non-cigarette tobacco such as cigars has increased–particularly among the young (6)–with aficionados looking forward to a range of flavors, including nutty, earthy, sweet, chocolate, and fruity. Contrary to cigarette tobacco, cigar tobacco requires a fermentation process (1). This process breaks down the proteins, cellulose, and starch and converts the resulting sugars and amino acids into a range of VOCs (1), which the team set out to pinpoint using several analytical techniques.

In this study, the team used a combination of an electronic nose (E-nose), headspace solid-phase microextraction-gas chromatography–mass spectrometry (HS-SPME-GC–MS), and headspace gas chromatography-ion mobility spectrometry (HS-GC–IMS) for a multidimensional analysis on nine groups of FTLs. E-nose is used in a range of industries, including food, pharma, cosmetics, and agriculture, for the purposes of quality control. The E-nose data revealed a gradual increase in nitrogen-oxygen compounds throughout fermentation, suggesting their influence on the tobacco’s aroma. HS-SPME-GC–MS detected 56 VOCs, while HS-GC–IMS identified 55 VOCs, highlighting the complexity of the volatile profile. Principal component analysis (PCA) revealed significant differences between FTLs at different fermentation stages.

To refine their findings, the researchers employed partial least squares discriminant analysis (PLS-DA) to isolate 12 key VOCs as markers of the fermentation process. These metabolites are primarily involved in critical biochemical pathways, including pyruvate, phenylalanine, and nicotinate/nicotinamide metabolism, signifying their role in developing FTL flavor characteristics.

The team concluded that their study could enhance the understanding of flavor development during tobacco fermentation and offers insights into optimizing fermentation techniques. Helping producers to improve the quality and consistency of cigar tobacco products can help to build up more refined and distinctive flavor profiles in the industry.

References

(1) Zhang, M.; Guo, D.; Wu, G.; et al. Analysis of Volatile Compound Metabolic Profiles During the Fermentation of Filler Tobacco Leaves Through Integrated E-Nose, GC–MS, GC-IMS, and Sensory Evaluation. J. Chromatogr. A 2024, 1737, 465472. DOI: 10.1016/j.chroma.2024.465472

(2) Geng, Z.; He, P.; Gao, H.; et al. Aroma Precursors of Cigars from Different Tobacco Parts and Origins, and Their Correlations with Sensory Characteristics. Front. Plant Sci. 2023, 14, 1264739. DOI: 10.3389/fpls.2023.1264739

(3) Action on Smoking and Health. https://ash.org.uk (accessed 2024-12-02).

(4) World Health Organization, WHO global report on trends in prevalence of tobacco use 2000–2030. https://www.who.int/publications/i/item/9789240088283 (accessed 2024-12-02).

(5) World Health Organization, Tobacco use declines despite tobacco industry efforts to jeopardize progress. https://www.who.int/news/item/16-01-2024-tobacco-use-declines-despite-tobacco-industry-efforts-to-jeopardize-progress (accessed 2024-12-03).

(6) So Britain’s Young People Are Taking Up Pipes And Cigars? This Was A Trend I Had To Investigate, The Guardian, https://www.theguardian.com/commentisfree/2024/mar/16/britain-young-people-pipes-cigars (accessed 2024-12-02).