Material guide · 172
Material guide: sulfurol — 27th in the database by supplier count, and no perfumer has heard of it
· 22 min read
CAS 137-00-8, 105 suppliers, with only 26 materials in the whole database carrying more. Yet its odor field reads fatty, cooked, beef juice, meaty, brothy, nutty, yeasty, bready, oily, sulfurous, and its odor family is meaty. This material lives in the flavour world, and a perfumer will never meet it. The notes field explains what it is in one line: the thiazole portion of thiamine. Vitamin B1 is a pyrimidine ring and a thiazole ring bridged together; cut off the thiazole half, hang an ethanol chain on it, and this is what you get. The occurrence list matches that origin, being entirely things that have been heated: roasted beef, beer, brandy, cocoa, cognac, roasted peanut, wine, with porcini and malt added by the notes. A 2003 University of Florida paper made the point cleanly: put 0.024 mM thiamin in model orange juice at 35 °C for eight weeks and 13 aroma-active components appear, two of them within days and accounting for 33% of total aroma activity by day seven, detected by nose before the instrument found them. The same chemistry is flavour in beef and spoilage in juice.
About a 5 minute read.
Too long, didn't read
- Name: sulfurol, properly 4-methyl-5-thiazoleethanol, CAS 137-00-8, 105 suppliers
- 27th in the whole database by supplier count; only 26 materials have more
- Odor family meaty; descriptors: fatty, cooked, beef juice, meaty, brothy, nutty, yeasty, bready, oily, sulfurous
- The notes field, in one line: the thiazole portion of thiamine
- Listed in all four regulatory indexes: JECFA 1031, FEMA GRAS 3204, CoE 11621, FLAVIS 15.014, and FCC listed
- Specific gravity 1.192–1.210 (heavier than water), vapour pressure 0.003 mmHg, longevity field empty
- The supplier odour samples on record are 10% in ethanol and 10% in PG, not neat
27th, and no perfumer has heard of it
Start with the scale. 105 suppliers means only 26 materials out of 42,225 carry more. It sits in the same bracket as geraniol and clove bud oil.
Then read its odor field: fatty, cooked, beef juice, meaty, brothy, nutty, yeasty, bready, oily, sulfurous. Odor family meaty. This is not in any perfume.
Only 46 materials in the database carry the odor family meaty, and the six best supplied are:
| Material | Suppliers | First descriptors |
|---|---|---|
| sulfurol | 105 | fatty, cooked, beef juice, meaty, brothy |
| 2-methyl-3-tetrahydrofuran thiol | 61 | roasted beefy, chicken, meaty, sulfurous |
| methionol | 44 | sulfurous, onion, sweet, soup, vegetable |
| bis(2-methyl-3-furyl) disulfide | 43 | meaty, roasted, scallion, onion, sulfurous |
| sulfuryl acetate | 43 | meaty, beef juice, beefy, brown, brothy |
| meaty dithiane | 27 | pork, lamb, chicken, savory, bouillon, onion |
Add up the savoury side of the odor families (meaty, roasted, alliaceous, cheesy, onion, burnt, nutty, vegetable, cabbage, fatty, sulfurous) and you get 593. The perfumery side (floral, woody, musk, citrus, fruity, green, herbal, balsamic, amber, aldehydic) totals 4,343. 7,001 records carry an odor family at all.
So the database's centre of gravity really is on the perfumery side. The supplier count column is not, though. That column records what the flavour industry actually moves, and that world is bigger than perfume. When the ethyl acetate piece found DPG mentioned only 222 times, it was the same fact seen from the other side.
It is half of vitamin B1, cut off
The first sentence of the notes field says it: the thiazole portion of thiamine.
Thiamine (vitamin B1) is a pyrimidine ring and a thiazole ring joined by a methylene bridge. Take the thiazole half on its own, with a methyl group on the ring and an ethanol side chain, and that is 4-methyl-5-thiazoleethanol, which is sulfurol.
The occurrence field matches that ancestry, because everything on it has been heated: grilled beef, roasted beef, beer, brandy, cocoa, cognac, roasted peanut, rape and wine. The notes add porcini (Boletus edulis) and malt.
Nothing raw. The pattern points at one mechanism: something containing thiamine gets hot, the thiamine breaks apart, and the thiazole half comes out as an odorant.
In orange juice, the same chemistry is called spoilage
In 2003 Dreher, Rouseff and Naim at the University of Florida's Citrus Research and Education Center ran a clean experiment (PMID 12720398).
The design: model orange juice solutions containing 0.024 mM thiamin hydrochloride, stored for up to eight weeks at 35 °C in amber glass. Volatiles were evaluated primarily by gas chromatography with olfactometry, alongside a flame ionization detector and a pulsed flame photometric detector (PFPD).
The result: they identified 2-methyl-3-furanthiol (MFT) and its dimer, bis(2-methyl-3-furyl) disulfide (MFT-MFT), confirming that thiamin could serve as the precursor to these potent off-flavours in thermally degraded citrus juices.
The numbers: 13 aroma-active components were observed in total. MFT and MFT-MFT appeared after only a few days of storage and produced 33% of the total aroma activity after 7 days. Both were observed olfactometrically earlier than they could be detected using PFPD.
Other aroma-active compounds included 4,5-dimethylthiazole (skunky, earthy), 3-thiophenethiol (meaty, cooked), 2-formyl-5-methylthiophene (meaty) and 2-methyl-3-(methyldithio)furan (meaty).
Two things there are worth a pause.
First, MFT-MFT is in the table above, at 43 suppliers with the odor family meaty. In a beef flavour product it is an ingredient; in orange juice it is a defect. The molecule does not change, only where it turns up. That is the same structure as ethyl acetate going from fruit to nail polish remover in Calvados.
Second, the nose beat the instrument. The GC-O sniffing port caught those two before the PFPD did, because their thresholds sit below the instrument's detection limit. A concrete case for odour thresholds.
How industry makes meat flavour without meat
In 2020 Raza and colleagues at Beijing Technology and Business University did the other half of the story (PMID 33026027): glutathione-enriched yeast extract (GSH-YE), with partial additions of cysteine and ribose, run through the Maillard reaction to simulate beef-like aroma.
They optimised the reaction conditions with a central composite design and characterised the key odorants by HS-SPME-GCMS. The optimised conditions produced numerous pyrazines, furans, thiazoles and sulfur- and nitrogen-containing compounds, with the predominant odorants being 2,5-dimethylfuran, 2,5-dimethylpyrazine, thiazole, 2-methyl-3-furanthiol, dimethyl trisulfide, 3,5-diethyl-2-methylpyrazine, 3,3'-dithiobis[2-methylfuran] and 2-methyl-3-(methylthio)furan.
They also recorded how sensitive the process is: initial pH and thermal temperature each changed the whole volatile profile dramatically, and cysteine and other amino acids were consumed faster at higher temperatures.
Modern meat flavour, in other words, does not come from meat. It comes from the Maillard reaction between yeast, amino acids and sugar, and thiazoles are regulars on the product list. Sulfurol is the member of that family you can buy to a stable specification.
Physical data: heavy, barely volatile, and no longevity
| Field | Value |
|---|---|
| Specific gravity @25 °C | 1.192–1.210 (heavier than water) |
| Refractive index @20 °C | 1.548–1.552 |
| Boiling point | 279–281 °C @760 mmHg; 135 °C @7 mmHg |
| Flash point | > 110 °C |
| Vapour pressure | 0.003 mmHg (est) |
| Water solubility | 9,081 mg/L (est) |
| Longevity | (empty) |
0.003 mmHg is very low, three times lower than eugenol at 0.010. And the longevity field is empty.
That blank is worth noticing. This database's longevity numbers come from smelling blotters, and nobody evaluates a meat material on a blotter. Its working life is being added to a soup or a sauce at parts per million and then eaten. The longevity field has nothing to hold, not because data is missing, but because the measurement does not apply to this material.
One more detail: the supplier odour samples on record are "10% in ethanol" and "10% in PG". It already circulates in catalogues as a dilution.
Buying and storing
105 suppliers, so supply is not a concern. The practical questions differ from a fragrance material:
- Confirm your use is within what it is cleared for. Its regulatory identity is a flavour material (JECFA 1031, FEMA 3204, CoE 11621, FLAVIS 15.014, FCC listed). The cosmetic uses field does say perfuming agents, but for anything on skin, check the current rules yourself.
- Buy the dilution, not the neat material. The sample form in the catalogue is 10%. At the use levels involved, neat material makes no sense for small-batch work.
- It is heavier than water (1.192–1.210), which is unusual on a perfumery bench. Do not convert by volume when weighing.
- Flash point > 110 °C and a vapour pressure of 0.003 make it one of the least volatile materials in this series, nearly forty thousand times below ethyl acetate at 111.7 mmHg.
- Structure class II (Cramer Class II); oral LD50 2,450 mg/kg in rat.
→ Sulfurol in the database: full physical data, 105 suppliers and suggested blends.
What this article does not establish
- "The supplier count reflects flavour industry volume" is inferred from this material's rank and odor family. The database does not record which industry a supplier belongs to.
- 593 against 4,343 uses odor family groupings I chose. There is no official boundary between savoury and perfumery families; a different word list gives different numbers.
- Dreher's study was model orange juice, not real juice and not meat. What it establishes is that thiamin can be the precursor of those off-flavours, not that the pathway in beef is identical.
- That paper did not detect sulfurol itself, but other products of the same thiamin breakdown. I use it for the mechanism, not as a measurement of this material.
- I attribute the empty longevity field to the measurement not applying; the database gives no reason.