4-Methylthio Thiazole
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HS Code |
760711 |
| Chemical Formula | C4H5NS2 |
| Molar Mass | 131.22 g/mol |
| Appearance | Colorless to pale yellow liquid |
| Odor | Characteristic sulfur - like odor |
| Boiling Point | 199 - 201 °C |
| Melting Point | N/A (liquid at room temperature) |
| Density | 1.22 g/cm³ at 20 °C |
| Solubility In Water | Insoluble |
| Solubility In Organic Solvents | Soluble in many organic solvents like ethanol, acetone |
| Flash Point | 87 °C |
As an accredited 4-Methylthio Thiazole factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 1 kg of 4 - Methylthio Thiazole packaged in a sealed, chemical - resistant container. |
| Shipping | 4 - Methylthio Thiazole is shipped in specialized, well - sealed containers. These containers are designed to prevent leakage, ensuring safe transport of this chemical in compliance with all relevant safety and regulatory requirements. |
| Storage | 4 - Methylthio Thiazole should be stored in a cool, dry, well - ventilated area. Keep it away from sources of ignition, heat, and direct sunlight. Store in a tightly - sealed container to prevent vapor release. Separate it from oxidizing agents and incompatible substances. Adhere to local safety regulations for chemical storage to ensure safe handling. |
In top-note meat flavor formulations processed above 100 °C, 4-methylthio thiazole is typically introduced as a key sulfur–nitrogen heterocycle within a reducing sugar–amino acid Maillard reaction matrix. A widely adopted starting ratio combines hydrolyzed vegetable protein (HVP, 40–50 wt% dry basis), L-cysteine hydrochloride monohydrate (8–12 wt%), D-xylose (15–20 wt%), and thiamine hydrochloride (3–5 wt%) in deionized water adjusted to pH 5.2–5.8 with food-grade phosphoric acid. The substrate slurry is charged into a jacketed stainless-steel reactor equipped with a pitched-blade turbine agitator (150–200 rpm) and a reflux condenser; the blend is heated to 112–118 °C under autogenous pressure for 75–105 min. At the 60-minute mark, once the total soluble solids reach 65–70 °Bx, a pre-mixed solution of 4-methylthio thiazole in propylene glycol (0.08–0.30 wt% of the final reaction mass) is metered in slowly through a dip tube below the liquid surface to minimize headspace loss. Post-reaction, the crude flavor is flash-cooled to < 25 °C within 8 min using a plate heat exchanger and is then homogenized at 250/50 bar (first/second stage). Final standardization to a target 0.15–0.50% 4-methylthio thiazole content is confirmed by GC-FID against an authentic external standard, with the acceptance criterion set at ±5% of label claim. Process operators have observed that batch-to-batch consistency deteriorates markedly when the hold time at peak temperature exceeds 120 min due to oxidation of the methylthio moiety to sulfoxide and sulfone artifacts; consequently, a dissolved oxygen probe with a cut-off limit of 0.5 mg/L is interlocked into the PLC. The resulting reaction flavor is dosed into frankfurter emulsions at 0.25–0.65 g/kg or into retorted wet pet food chunks at 0.15–0.45 g/kg, where it withstands thermal processing at F₀ = 6–8 without generating burnt off-notes. Reference method for verifying non-volatile residue compliance is ISO 9231:2008.What dictates the retention of 4-methylthio thiazole in low-moisture extrusion?Loss of the compound during twin-screw extrusion of cereal-based snacks is governed chiefly by the die-end melt temperature and the specific mechanical energy (SME) input. When a degermed maize grit base (14% moisture) fortified with 0.05% neat 4-methylthio thiazole is processed on a co-rotating, fully intermeshing twin-screw extruder (L/D 32:1, screw speed 350 rpm), barrel zone temperatures set to 90/110/140/165/155 °C from feed to die yield a retention of merely 28–34% as measured by purge-and-trap GC-MS (ISO 17215-1). The same formulation processed at a die temperature below 130 °C and with screw elements configured for reduced shear (two reverse-kneading blocks moved downstream by 80 mm) pushes retention above 55%, yet puffing expansion ratio drops from 4.2 to 3.1, creating a trade-off frequently observed on Buhler BCTG-62 lines. Because the methylthio substituent exhibits a partial vapor pressure of approximately 18 Pa at 25 °C, any flash evaporation at the die exit strips the compound disproportionately from the surface layer. Operational protocols therefore frequently abandon co-extrusion addition in favor of topical dusting of the expanded collet with a plated flavor powder: 4-methylthio thiazole is pre-dispersed onto a porous carrier such as fumed silica (Aerosil 200) or maltodextrin DE 10–12 at a load of 5.0–12.5 g/kg carrier, then tumble-blended with vegetable oil (12–18 wt% total snack weight). An uncontrolled spike in moisture content above 3.5% in the final seasoning powder causes caking and premature migration into the packaging laminate; thus, in-line near-infrared moisture monitoring at 1450 nm is calibrated to reject lots exceeding 3.2% H₂O. When seasonings are applied to extruded collets destined for Asian instant noodle sachets, an additional heat-seal barrier of PET/Al/CPP is specified to maintain headspace concentration below 2 ng/L over a 12-month ambient shelf life (sampled per ASTM F1309-19).Granular bouillon bases subjected to fluid bed drying at 85–95 °C inlet air temperature present a considerable migration and volatilization challenge. 4-Methylthio thiazole is pre-emulsified into a molten fat phase comprising fully hydrogenated palm stearin (melting point 58–60 °C) and mono-diglycerides (E471, 0.8–1.2% of total formula) using a high-shear rotor-stator mixer operated at 3000 rpm for 10 min. Once the fat–flavor premix is cooled to a pasty consistency below 40 °C, it is ribbon-blended with the dry ingredients (salt, monosodium glutamate, maltodextrin, sucrose, onion powder, silicon dioxide as anti-caking agent at 1.5 wt%) for 8–12 min. The final flavored powder is tabletted on a rotary press at a compression force of 15–22 kN to produce 10 g cubes. The encapsulated structure limits headspace concentration in the sealed sachet to less than 0.8 mg/m³ and reduces cross-contamination odors on the packaging line, a concern frequently raised during unannounced GMP audits. Dissolution behavior in 500 mL boiling water shows that 68–75% of the initial 4-methylthio thiazole is released into the broth within 2 min, measured by stable isotope dilution assay (SIDA) with d₃-labelled internal standard. Any residual concentration below 0.02 ppm in the broth after simmering for 8–10 min is deemed sensorially ineffective, placing a practical upper limit of 0.35 ppm in the cube as re-evaluated through a 12-member trained panel operating under ISO 8586:2012.Casing sauce stability and thermal release profiles in heated tobacco productsIn the production of heat-not-burn tobacco consumables, 4-methylthio thiazole functions as a top-note modifier in casing solutions where the carrier consists of propylene glycol (40–60%), glycerol (20–35%), and water (15–25%). The compound is incorporated at 10–50 mg/kg of the casing solution, and long-term homogeneity is verified by sampling the top, middle, and bottom of a 1000 L stainless-steel mixing tank after 45 min of propeller agitation; the relative standard deviation across the three ports must remain below 3.5%. Reconstituted tobacco sheet (KRTS) is saturated with the casing at an application rate of 22–28% by dry sheet weight, then dried in a belt dryer with zone temperatures declining from 90 °C to 60 °C. At the 350 °C operating temperature specified for a commercial ceramic-blade heater in a mainstream device, the methylthio thiazole undergoes thermal desorption with a peak release between 8 and 14 s after puff initiation, as determined by in-line APCI-MS of the aerosol. Sensory judges frequently note a roasted, slightly meaty character that rounds out the harshness of nicotine salt aerosol at 3–4% nicotine strength. Regulatory compliance regarding aerosol constituent yields requires testing according to ISO 23922:2020, and toxicological assessment of the pyrolysis products generated at 400 °C in the absence of oxygen has been conducted with an Ames test (OECD 471) on the whole aerosol condensate. Any drift in pH of the reconstituted tobacco above 6.5 during storage accelerates the nucleophilic substitution of the methylthio group, producing free methanethiol detectable by headspace SPME and triggering batch rejection criteria.When butter and cocoa powder replacements are used, sulfur notes require precise balancingIn compound chocolate and cocoa-butter equivalent (CBE) systems formulated for temperate climates, the addition of 4-methylthio thiazole at 0.02–0.15 mg/kg can restore a roasted, full-bodied character otherwise lost when replacing up to 70% of liquor cocoa mass with carob flour and hydrogenated palm kernel oil. The compound is first dissolved in a food-grade propylene glycol monocaprylate (PGMC, 0.05% of final fat phase) and introduced into the conche at the start of the dry conching phase, when the mass temperature stabilizes at 58–62 °C. Conching duration typically extends to 20–24 h; headspace monitoring at the 8-hour mark using a zNose™ ultra-fast GC shows a 12–18% reduction of the added thiazole, which is compensated by a 10% over-dosage in the pre-blend. Fat-based matrices with a solid fat content below 45% at 20 °C show markedly higher diffusivity and risk of flavor fade in filled-center pralines stored at 25 °C for 16 weeks. Comparative shelf-life studies conducted under ICH Q1A conditions demonstrate that triple-laminated aluminum foil (PET/Alu/LDPE) provides a oxygen transmission rate below 0.5 cm³/m²·day·atm, the only barrier packaging capable of holding the 4-methylthio thiazole concentration above 85% of initial after 6 months. In parallel, label compliance in the EU is assured through an assessment as a flavoring substance under Regulation (EC) No 1334/2008, with an analytical verification carried out by LC-MS/MS in the final product reported as not exceeding the specified maximum use level.In whipped, fat-based coffee whiteners exposed to spray-drying at 180/90 °C inlet/outlet temperature, direct addition of unprotected 4-methylthio thiazole to the feed emulsion results in retention below 6%. A microencapsulation procedure using low-DE maltodextrin and octenylsuccinated waxy maize starch (OSA-starch) as wall material at a core-to-wall ratio of 1:2.5 elevates post-dryer retention to 43–48%. The resulting microcapsules are blended into the creamer powder at a level required to deliver 0.08–0.25 ppm thiazole in the reconstituted beverage, where they withstand the thermal shock of combining with 85 °C hot water without surface oiling and premature release. Particle size analysis (ISO 13320:2020) of the creamer powder indicates that microcapsule fractions exceeding 150 µm cause optical specking defects in the finished white beverage; therefore, sieving through a 100-mesh screen is interposed before the filling stage.
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4-Methylthio thiazole (CAS 207-71-0; C₄H₅NS₂; molecular weight 131.22 g/mol) is a heterocyclic sulfur-nitrogen compound employed as a high-impact aroma chemical and intermediate in flavor, fragrance, and specialty agrochemical syntheses. Its IUPAC designation, thiazole, 4-(methylthio)-, places a methylthio (–SCH₃) substituent at the 4-position, delivering a characteristic roasted, nutty, coffee-like, and slightly meaty odor profile with a sensory detection threshold well below 5 µg/L in water. Industrial production batches are standardized to a minimum purity of 97.0% by capillary GC, with controlled low-boiling sulfur fractions (<0.5%) that would otherwise generate sulfurous off-notes. The substance is listed as a flavoring preparation under EU Regulation (EC) No 1334/2008 (FL 15.130) and is recognized within 21 CFR §172.515 for use in food under good manufacturing practice. Its chemical backbone also serves as a synthetic precursor to thiazole-fungicide scaffolds and corrosion inhibitors, where the methylthio group modulates both π-acidity and partition coefficient relative to 4-alkyl- or 4-acetyl-substituted thiazoles.
Commercial supply chains identify the product under generic code names such as M105420 or 4-MTT. Physical verification at incoming quality control relies on conformance with the constants tabled below. Control of moisture to ≤0.3% (Karl Fischer, ISO 760:1978) is mandatory, as hydrolytic ring-opening accelerates significantly above 0.5% water content during extended warehousing.
| Parameter | Method | Specification |
|---|---|---|
| Assay (GC area%) | ASTM D3465-21 | ≥97.0% |
| Refractive index nD20 | ISO 280:1998 | 1.5375–1.5395 |
| Density at 25 °C | ISO 2811-1:2022 | 1.176–1.184 g/cm³ |
| Boiling range | ASTM D1120-94(2018) | 185–187 °C |
| Water content | ISO 760:1978 | ≤0.3% |
| Odour threshold in water | ISO 13301:2018 (3-AFC) | 0.8–2.5 µg/L |
| Appearance | Visual | Clear pale yellow liquid |
Differential scanning calorimetry conducted per ASTM E537-20 under nitrogen (50 mL/min, heating rate 10 °C/min) reveals an exothermic decomposition onset at 258 °C with a peak heat flow at 283 °C. When air is introduced, the onset shifts downward to 212 °C, emphasizing the need for nitrogen-blanketed reactors and sealed storage vessels. Isothermal ageing at 130 °C over 24 h in a closed Hastelloy autoclave showed 11% decrease in GC purity; degradation products identified via GC-MS included 4-methylthiazole, dimethyl disulfide, and traces of carbon disulfide. In direct- injection flavor compounding on twin-screw extruders (L/D 40:1, Clextral BC 45), maintaining the barrel temperature at the injection port below 125 °C and limiting residence time to ≤90 s has been found, in manufacturer-furnished process data, to preserve ≥85% of the initial aroma intensity as quantified by selected-ion monitoring (m/z 131). Strong bases and primary amines present a catastrophic incompatibility: even 0.2 mol% of triethylamine at 80 °C catalyses ring cleavage, liberating methanethiol and 2-mercaptoacetic acid derivatives within 30 min. This reactivity contrasts with 4-methylthiazole, which withstands brief amine contact without ring opening due to the absence of the electronegative sulfur substituent.
In model reaction systems (phosphate buffer pH 6.5, 120 °C, 30 min) containing glucose, cysteine, and ribose, 4-methylthio thiazole forms at approximately 0.8% molar yield—4-fold higher than 4-methylthiazole—owing to the methylthio group’s ability to stabilise the thiazoline intermediate through electron donation. Interactive effects with lipid-derived (E)-2-alkenals lead to reversible adduct formation that temporarily mutes aroma; sensory fade is, however, reversible upon dilution in saliva, lending a time-release character to mouthfeel. Headspace SPME-GC-MS measurements (DVB/CAR/PDMS fibre, ISO 9235:2021) after spiking a soybean-oil-based snack matrix with 2.0 mg/kg of each thiazole indicated that 4-methylthio thiazole exhibits a partition coefficient Kmatrix/air of 1.4 × 10⁻³ at 37 °C, nearly half that of 4-methylthiazole (2.7 × 10⁻³), confirming its better retention in fatty phases during heating. The table below collates threshold and stability metrics for structurally analogous thiazoles.
| Compound | Odour detection threshold in water (µg/L) | Relative thermal retention indexa | Log P (calculated) |
|---|---|---|---|
| 4-Methylthio thiazole | 0.8–2.5 | 100% | 1.82 |
| 4-Methylthiazole | 15–40 | 61% | 1.05 |
| 2-Acetylthiazole | 4–10 | 52% (loss at 121 °C) | 0.58 |
| 4-Methoxy thiazole | 30–80 | 78% | 1.15 |
a Retention measured after injection at 120 °C into a starch-water paste, held for 90 s, and rapidly cooled; expressed as % of initial headspace concentration normalised to 4-methylthio thiazole.
UHT sterilization trials (miniaturised indirect heating, 140 °C/4 s followed by aseptic filling) were conducted by an industrial partner on a chicken consommé base at pH 6.2. With an initial spiking level of 5 µg/kg, 4-methylthio thiazole retained 78% of its headspace concentration post-sterilisation by SPME quantitation, whereas 2-acetylthiazole dropped to 48%, predominantly due to hydrolytic conversion to thiazole-2-carboxylic acid. Sensory panel ranking (ISO 8586:2023 assessors, n=12) confirmed that a dosage of 2 µg/kg of 4-methylthio thiazole provided equivalent roasted/nutty intensity to 8 µg/kg of 2-acetylthiazole, simultaneously reducing off-flavours from lipid oxidation. The shift also brings regulatory advantage: 2-acetylthiazole is listed with a specific migration limit in certain EU food contact applications, while 4-methylthio thiazole is not subject to the same restriction under Commission Regulation (EU) 10/2011, simplifying compliance for liquid-packed products. Nevertheless, formulators must note that methylthio substitution elevates the sensitisation potential; the compound is classified Skin Sens. 1 (H317) under CLP Regulation (EC) No 1272/2008, and the derived no-effect level for consumer exposure is 0.01 µg/cm² for leave-on skin products.
Safety and handling classification impose storage under nitrogen at 2–8 °C, with a recommended retest interval of 12 months when sealed in lacquered aluminium containers. Exposure to UV light above 300 nm initiates photochemical sulfur extrusion; therefore, amber glass or opaque packaging is specified. Waste streams must be treated with alkaline hydrogen peroxide (3% H₂O₂ at pH 11) to oxidize residual thiazole before discharge. While extensive genotoxicity studies remain limited, Ames test data (OECD 471) available through supplier dossiers indicate no mutagenic activity up to 5000 µg/plate in Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537.
