Sun-cured tobacco is leaf dried in direct sunlight with no artificial heat, and Swedish Match says the tobacco in its snus is “air and sun-dried” — but no law that governs snus defines the term, requires it on a can, or lets anyone check it. FDA names sun-curing as one of four curing methods. USDA’s own classification regulation recognises three, and files “Virginia sun-cured” inside the air-cured class as a geographic market label. Nobody has ever measured a sun-cured snus against an otherwise-cured one.
This is one of those words that sounds like a specification and behaves like an adjective. It is not invented — sun-curing is a real process with a real chemical consequence, and the company that makes most of the world’s snus publishes a sentence saying it uses sun-dried leaf. But the distance between “a maker says this” and “you can verify this” is the whole story, and it is wider than I expected. If you want the process rather than the vocabulary, how Swedish snus is made, from leaf to can is the companion piece, and the snus pillar is the place to start cold. Regional snus styles across Sweden is the companion to this one: the same shape of question, about place rather than process.
What sun-curing actually is
The clearest statement of the taxonomy comes from an unexpected place — FDA’s 2017 proposed product standard for N-nitrosonornicotine in smokeless tobacco, which includes a section on curing techniques. It says: “There are four main methods for curing tobacco: Sun, air, flue, and fire curing.” And it distinguishes them: “Sun-cured tobacco is cured on outdoor racks exposed to the sun while air-cured tobacco is cured on racks in a well-ventilated barn under ambient temperatures (Ref. 4). Flue and fire curing occur in artificially heated and ventilated barns.” On duration, it says only that “Curing can take from a few days to several weeks depending on the curing method (Ref. 44).” And on why any of it matters at all: “The curing process not only dries out and preserves the tobacco but also imparts characteristic flavor.”
That is a proposed rule, and I could not establish whether it was finalised or withdrawn — treat it as FDA’s published characterisation rather than a standard in force.
The research side agrees on the definition and immediately flags the problem with it. A 2026 study in Frontiers in Plant Science from Hunan Agricultural University opens: “Sun-cured tobacco is cured by means of natural sunlight, a process that is highly susceptible to fluctuations in external environmental conditions, hindering standardized production and consequently leading to poor quality consistency.” The distinguishing feature is light, not heat: “Light exposure is essential in the curing process of sun-cured tobacco and represents the most distinct difference compared to the curing methods of flue-cured tobacco.” Its cycle ran nine days through yellowing, colour-fixing and stem-drying. Two of its authors were employed by Hunan Tobacco Company, a subsidiary of the China National Tobacco Corporation, and the paper says so.
And “sun-cured” covers at least three unrelated things: Chinese sun-cured yellow tobacco, American Virginia sun-cured, and Greek and Turkish oriental leaf.
The term is defined in US law — as a place, not a process
I expected a clean negative here and did not get one. “Sun-cured” appears 23 times in the Code of Federal Regulations. But look at how.
7 CFR Part 30, the tobacco classification regulation, defines exactly three cures as processes. Flue-cure, at § 30.11, is “To cure tobacco under artificial atmospheric conditions by a process of regulating the heat and ventilation without allowing smoke or fumes from the fuel to come in contact with the tobacco.” Fire-cure, at § 30.12, is “To cure tobacco under artificial atmospheric conditions by the use of open fires, the smoke and fumes of which are allowed to come in contact with the tobacco.” Air-cure, at § 30.13, is “To cure tobacco under natural atmospheric conditions without the use of fire, except for the purpose of preventing pole burn (house burn) in damp weather.” There is no section headed “Sun-cure” in Part 30 or in Part 29, and I checked every section heading in both.
Where sun-cured does appear, it is a market label tied to a geography. 7 CFR 30.38(g) and 29.3560 both define type 37 as “That type of air-cured or sun-cured tobacco commonly known as Virginia Sun-cured, Virginia Sun and Air-cured, or Dark Air-cured of Virginia, and produced principally in the central section of Virginia north of the James River.” Note the “or”: the type is defined by where it is grown, with the curing method as an alternative description. And Part 30 then files it under “Class 3b, Dark Air-cured tobacco, including types 35, 36, and 37”. The US regulatory system treats sun-curing as a variant of air-curing.
Sun-cured does make the statutory list of kinds of tobacco, at 7 CFR 29.1(j): “means any one of the following: Flue-cured, Burley, Fire-cured, Dark air-cured, Maryland or Virginia sun-cured.” But USDA publishes Official Standard Grades only for flue-cured tobacco — on its own grades and standards page, “flue-cured” appears fifteen times and “sun-cured” not once.
There is a nice piece of regulatory self-awareness in the same part. Oriental tobacco, the leaf most people mean when they say sun-cured, is deliberately not defined by curing. 7 CFR 30.44 says “Type designations for class 9 are based on (a) utilization, (b) curing method, or both, with no reference to physical characteristics”, then names type 92 foreign-grown flue-cured, 93 foreign-cured burley, 95 foreign-grown dark air-cured and 96 foreign-grown fire-cured — while type 91, the oriental class, is described by use and aroma alone.
So: the term is regulated, and it is regulated as a name for a particular Virginia dark tobacco. That is close to the opposite of what a snus marketer means by it.
Why curing method matters at all: nitrate, nitrite, nitrosamines
The reason anyone in the snus world cares about curing is tobacco-specific nitrosamines. The pathway is microbial. FDA sets it out plainly: “As the tobacco leaves are cured, the nitrate acts as a substrate for microorganisms reducing the nitrate to nitrite.” The nitrite then reacts with nicotine and nornicotine during curing to form compounds including NNN. A 2024 review supported by the National Institutes of Health and the CDC puts the same mechanism more precisely: “New mechanistic insights are presented regarding the role of dissimilatory nitrate reductases in certain microorganisms involved in the conversion of nitrate to nitrite that leads to the formation of NNN and NNK during curing and processing of tobacco.”
Curing method is one of the levers on that. FDA: “During the curing process, the curing method, humidity, air flow, temperature, and the fuel used for heating the tobacco influence the extent to which the NNN level changes (Refs. 45, 46).” And it publishes a ranking: “Studies have shown that flue and fire-curing tobacco results in higher NNN levels than when the same tobacco is air-cured (Refs. 47, 42, 1).” A Virginia Tech extension publication explains why flue-curing runs two ways at once — “The higher temperatures and accelerated drying of the leaf greatly reduces the activity of microorganisms responsible for TSNA formation”, but “the pathway for TSNA formation in flue-cured tobacco primarily involves nitrous oxides (NOx), produced as a by-product of combustion of LP or fuel oil, with specific alkaloids present in the tobacco”.
Here is the hinge of this whole article. FDA’s ranking is flue and fire above air. Sun is not in it. FDA names sun-curing in its taxonomy, and names it again when describing GothiaTek, and nowhere in that document does it say whether sun-cured tobacco carries more or less NNN than air-cured tobacco. The only sun-specific number FDA publishes is about storage, not curing: “Researchers have reported a 2-fold increase in NNN levels in sun-cured tobacco and a 3-fold increase in NNN levels in Burley tobacco when stored at ambient temperatures over a 1-year period (Ref. 41).”
And the published differences that do exist sit at the level of tobacco type rather than cure. FDA again: “Burley tobacco also contains more NNN compared to Virginia and Oriental types, whether grown in the same or different geographical locations (Ref. 37).” A study whose funding statement reads “Philip Morris International is the sole source of funding and sponsor of this research.” explains why burley is the high-TSNA type, and the answer is agronomy: “Interestingly, BU tobaccos also require exceptionally high nitrogen fertilization rates and accumulate more nitrate within the leaf”. Nitrate in the leaf is the substrate; curing is what the microbes do with it.
The one clean quantitative contrast that involves sun-curing is about sugar, not nitrosamines. A 2025 Chemical Research in Toxicology review, NIDA-funded with no competing financial interest declared, reports that “sugars may comprise 8–30% of tobacco weight in flue-cured Virginia tobacco and 10–20% in sun-cured Oriental tobacco because elevated temperatures prevent sugar metabolism”, against burley where “This is because Burley is typically subjected to air-curing, a slow processing method that allows sugars to be enzymatically metabolized” and sugars “account for only <0.2% of tobacco weight”. Sun-curing, on that measure, behaves like flue-curing rather than like air-curing: heat beats enzymes.
The methods, side by side
Blank cells are honest. I did not find a source for them.
| Sun-curing | Air-curing | Flue-curing | Fire-curing | |
|---|---|---|---|---|
| Heat source | None; leaf on outdoor racks in direct sun | Ambient, “without the use of fire, except for the purpose of preventing pole burn” — though US practice uses gas burners, coke stoves or small wood fires in damp weather | Artificial heat, smoke kept away from the leaf | Open fires, smoke in contact with the leaf |
| Duration | Nine days in one controlled trial; FDA gives only “a few days to several weeks” for curing generally | About four weeks for the main changes; ten weeks in a barn, or 56 ± 10 days in a field trial | Roughly 144 hours, stepping 100°F yellowing to 130°F leaf drying to 160°F stem drying | “Six to seven weeks to fire-cure a crop of dark tobacco by conventional means” |
| Sugars | 10–20% in sun-cured oriental | <0.2% in burley | 8–30% in flue-cured Virginia | Not sourced |
| Nitrosamines | No published comparison against any other method. One storage result only: 2-fold NNN increase over a year at ambient temperature | Microbial nitrate-to-nitrite route; higher with high humidity; burley’s load driven by leaf nitrate | Lower microbial route, but a combustion NOx route instead | Highest of the four on FDA’s own ranking |
| Used in snus? | Yes, per the maker | Yes | No — excluded by GothiaTek’s no-artificial-heat description | Formerly yes; phased out in the 1990s |
What Swedish snus is actually made from, on the record
Swedish Match does publish a curing claim, on its snus production page, under a heading about raw material requirements: the tobacco in its snus products “is air and sun-dried” and is selected so that internal limits for undesired substances are met for each product.
Its own scientists put it more firmly in a peer-reviewed paper. A 2011 article in Harm Reduction Journal describing the GothiaTek standard says “The components of Swedish snus are a blend of air and/or sun-cured tobacco, water, sodium chloride, sodium carbonate, humectants, and flavoring agents.” and, of snus made to the standard, that it “is exclusively made from selected, low-nitrosamine raw tobacco (N. tabacum) that has been air or sun-cured. This means that curing is achieved without artificial sources of heat and humidity.” That is the most specific curing statement in print about Swedish snus — and the competing-interests statement reads “All authors are or have been employees of Swedish Match AB.” The paper carries no funding statement, and its figures are sourced to internal company documentation. It says so itself.
Then the record starts disagreeing with itself. The same company’s consumer FAQ says snus “consists of air-dried ground tobacco, water, salt, flavoring and taste additives and is pasteurized in a heat-treatment process, which produces very low levels of harmful substances”, with no mention of sun. Its business overview says the product “contains selected air-dried tobacco variations, water, salt, softening agent, conservatives and flavoring.” So of three pages on one website, one says air and sun, two say air.
FDA contradicts itself inside the same document. Describing Swedish snus: “It typically consists of low-nitrosamine tobacco that has been air-cured, moistened, ground, and heat treated (Refs. 4, 12, 11).” Then, in the next paragraph, describing the standard that governs it, FDA says GothiaTek establishes limits for low-nitrosamine raw tobacco that has been air-cured or sun-cured. Of American snus, it says: “From the limited information available, snus manufactured in the United States appears to consist of tobacco that has been air-cured or sun-cured and is pasteurized or heat treated (Refs. 20, 21).”
None of this is bad faith. It is evidence that nobody downstream of the raw-material buyer has a reason to be precise, because nothing makes them be.
What GothiaTek actually audits, and it is not the method
This is the part that settles the question. The GothiaTek standard’s own published components, as the company’s paper enumerates them, are: maximum levels for undesired constituents in the finished product; guidance residue levels for agrochemicals; a raw-material standard described as “Leaf tobacco selection and an "early warning" chemical analysis program designed so that the limits for undesired constituents in finished products are met.”; an ingredient policy; requirements for the manufacturing process covering particle size, controlled heat treatment, a closed system and hygiene; and consumer information.
There is no curing clause anywhere in that list. The standard audits the molecule in the finished can, not the process that produced the leaf. And the public GothiaTek standard page bears this out: across the whole page, “cure”, “curing”, “cured”, “sun” and “dried” return zero occurrences. What it publishes instead is a limits table — nitrite at 3.5 mg/kg against a 2025 content below 1, NNN and NNK combined at 0.95 mg/kg against 0.35, N-nitrosodimethylamine at 2.5 µg/kg, benzo(a)pyrene at 1.25 µg/kg. Measured outputs, not declared inputs. The GothiaTek standard, explained goes through the whole thing, and TSNAs in snus covers what those nitrosamine numbers mean. The same “measure the output, not the input” logic shows up in nicotine pouches and dry mouth, where the measurement simply does not exist yet.
If you want to know how far out of date the company’s own regulatory references are: that page still says snus in Sweden is regulated by LIVSFS 2012:6, an instrument the National Food Agency repealed on 5 March 2024 and replaced with LIVSFS 2024:2.
The one time changing the cure in snus was measured
There is exactly one before-and-after in the literature, and it is about fire-curing. From the same Swedish Match paper: “Traditionally snus was made from a selection of tobacco varieties typically including a large proportion of fire-cured tobacco. This resulted in relatively high levels of PAH:s in the finished products. During the 1990s use of fire-cured tobacco was phased out.” The measured result: “the level of B(a)P in finished snus products decreased from c. 20-25 ng/g to less than 2-3 ng/g based on dry weight”. And a consequence the company volunteers: “In part, flavoring is used to compensate for the fact that fire-cured tobacco is no longer used in snus”.
That is a real demonstration that the cure changes the product measurably. It is also the only one, it is about the method that was removed rather than the ones that remain, and the measurement is the manufacturer’s own. The other heat step in the process — pasteurisation — is covered in why Swedish snus is pasteurised and American snuff is fermented.
Nothing on a snus can has to say how the tobacco was cured
I grepped five instruments for every variant I could think of — sun-cured, suncured, sun-dried, soltorkad, lufttorkad, torkning, curing, cured, oriental, Turkish. The Swedish Food Act (2006:804), the Tobacco Act (2018:2088), the National Food Agency’s snus regulation LIVSFS 2024:2, the Agency’s own Kontrollwiki guidance article on snus, and the EU Tobacco Products Directive. Zero occurrences of every term, in all five documents.
The Directive mentions curing twice, and it is the same sentence twice — once as a recital and once as Article 7(3) — permitting “sugar to replace sugar that is lost during the curing process”. The EU’s only legislative acknowledgement that curing exists is a permission to add the sugar back.
The Swedish mandatory label is five items: net quantity in grams, day of manufacture, a storage instruction if storage affects shelf life, and the name and address of the manufacturer, packer or seller — and the address may be swapped for a website or a Swedish phone number. Section 13 adds that the pack must carry the designation snus or tuggtobak, and that a brand or fancy name may not be used in its place. And the ingredient declaration in descending weight order, at section 14, applies only to tobacco-free, nicotine-free snus-like products. A can of real Swedish tobacco snus is not required to carry an ingredient list at all, let alone a curing declaration.
Nor does the regulation say anything about claims. LIVSFS 2024:2 contains no occurrence of märkning, marknadsföring, reklam, presentation or påstående as applied to claims, and the Agency publishes no guidance on snus marketing claims. The only backstop is the general offence in the Food Act’s section 28 a, which reaches anyone who “i större omfattning märker, marknadsför eller presenterar ett livsmedel på ett sätt som är eller kan vara vilseledande” — misleading labelling, marketing or presentation, but only at scale.
Oriental leaf, and the one named sun-dried snus
I went looking for Turkish or Greek oriental leaf in Swedish snus and it is not there. Across 893 pages of swedishmatch.com, “oriental” appears four times: twice as a flavour description in snus marketing, twice in company history about cigarette blends. Not once as a raw material. Skruf publishes its tobacco origins — India, the Philippines and South Africa — and across all 74 pages of its site, soltorkad, sun-cured, sun-dried, lufttorkad, curing, oriental and Virginia all return zero. GN Tobacco says nothing about tobacco at all.
The one specific sun-dried product claim Swedish Match makes points to South America. A 2009 press release for Kardus, its limited-edition loose snus, says: “Air-dried tobacco from Guatemala, sun-dried tobacco from the province of Salta at the foothills of the Andes and a first-class, 23-year-old dark rum from Guatemala.” One product, in an edition of 500, seventeen years ago.
And the company’s own publication list makes the point better than I could. Of 166 papers it lists, four mention curing. Two are about TSNA formation during air-curing and are tagged to GothiaTek, snus and TSNA. One is about flue-curing Virginia tobacco. The fourth, its only sun-cured paper, is Volatile Acids of Sun-Cured Greek Nicotiana tabacum from 1973, tagged to structural chemistry and tobacco chemistry — not to snus, and not to TSNA.
What nobody has measured
No published study measures nitrosamines, nitrate or anything else in a snus product as a function of how its tobacco was cured. I searched for sun-cured against snus, against smokeless tobacco, against nitrosamines and TSNA, and against curing method generally, and inspected the titles returned; there is nothing. I should say that search engines loosen quoted phrases, so that is “I found none after reading the titles”, not a machine-proven zero.
No authority has published anything consumer-facing about curing claims on snus. No standards body document was reachable — both CORESTA and ISO refused automated access, so I am reporting those as unchecked rather than as silent.
So what should you do with the word?
Treat it as provenance, not as a grade. It says something real about how a leaf was dried, the way “air-dried” on another can does. It is the maker’s statement, and the maker has not been asked to prove it, because the standard governing the product checks what comes out rather than what went in — and on the evidence of that limits table, checking what comes out works. If you want a number that actually separates one snus from another, the ones that exist are nitrosamine content, moisture, grind and pH, and all four are measured. This is the same pattern as handmade versus machine-made snus: a word that sounds like a grade and turns out to have no instrument behind it.
Frequently asked questions
Is sun-cured snus lower in nitrosamines than air-cured snus? Nobody has measured it. FDA publishes a ranking that puts flue and fire curing above air curing for NNN, and does not place sun curing on that scale at all.
Is “sun-cured” a protected or regulated term? In US tobacco classification, yes — but as the name of a Virginia dark tobacco type defined by where it is grown, filed inside the air-cured class. In Swedish and EU law governing snus, no: the term does not appear.
Does any snus can have to tell me how the tobacco was cured? No. The Swedish mandatory label is five items, and a can of tobacco snus is not required to carry an ingredient list at all.
Is sun-cured the same as oriental or Turkish tobacco? Often that is what people mean, but the term also covers Chinese sun-cured yellow tobacco and American Virginia sun-cured, and US regulation pointedly declines to define the oriental class by its cure. No Swedish maker publishes that it uses oriental leaf in snus.
Was fire-cured tobacco ever in snus? Yes, in quantity, and removing it in the 1990s took benzo(a)pyrene in finished snus from about 20–25 ng/g down to under 2–3 ng/g by the manufacturer’s own measurement. That is the clearest evidence that the cure matters.
Sources
- FDA, Tobacco Product Standard for N-Nitrosonornicotine Level in Finished Smokeless Tobacco Products, proposed rule, 82 FR 8004 (PDF) — the four-method taxonomy, the curing-and-NNN discussion, and both characterisations of Swedish snus.
- 7 CFR Part 30 and Part 29 — the three process definitions, type 37, class 3b, and the class 9 type designations.
- USDA Agricultural Marketing Service, Tobacco grades and standards — official standard grades for flue-cured tobacco only.
- Rutqvist et al., Swedish snus and the GothiaTek standard, Harm Reduction Journal, 2011 — all authors Swedish Match employees; the curing specification, the GothiaTek components, and the fire-cured phase-out.
- Chen et al., Frontiers in Plant Science, 2026 — sun-curing definition and nine-day cycle; two authors employed by Hunan Tobacco Company.
- Stepanov et al., Sugars in Tobacco Products, Chemical Research in Toxicology, 2025 — sugar content by curing method; NIDA-funded.
- Hilfiker et al., Frontiers in Plant Science, 2022 — burley nitrate loading; sole funder Philip Morris International.
- Carcinogenesis, 2024 — dissimilatory nitrate reductases and TSNA formation; NIH and CDC funding named in the record.
- Reed, Curing Tobacco, Virginia Cooperative Extension (PDF) and University of Kentucky Extension ID-160 (PDF) — flue-curing schedule, NOx mechanism, air- and fire-curing durations.
- Livsmedelslag (2006:804) and Lag (2018:2088) om tobak och liknande produkter.
- LIVSFS 2024:2 (PDF) — the mandatory label and the ingredient-declaration split; and Kontrollwiki, snus and chewing tobacco.
- Directive 2014/40/EU (PDF) — recital 16 and Article 7(3), the sugar-replacement permission.
- Swedish Match, snus production, the GothiaTek standard page, its FAQ, the Kardus Superior Blend 2009 release and its publication list; Skruf’s production page; GN Tobacco.
Last verified 10 November 2026. CORESTA and ISO documents on tobacco terminology were unreachable and are reported as unchecked, not as silent.
