4-Methyl-5-Beta-Acetoxyethyl Thiazole: Chemical Properties, Uses, Safety Data & Supplier China

Thermal Stability Thresholds in Coffee and Cocoa Flavor Systems

In spray-dried instant coffee production, 4-Methyl-5-Beta-Acetoxyethyl Thiazole provides the characteristic roasted, nutty, and cocoa-like top notes essential to Colombian and Arabica blends. Regulatory clearance for this application spans multiple jurisdictions: FEMA GRAS 3205 permits use in non-alcoholic beverages at levels up to 0.5 ppm; EU Flavis 15.033 lists the substance within Annex I of Regulation (EC) 1334/2008 for coffee and cocoa categories; JECFA monograph 1751 confirms a no-safety-concern conclusion at current estimated intakes. Typical addition rates in spray-dried coffee powder fall between 0.1 and 0.5 ppm by weight of the final soluble solids, while cocoa powder used in beverage blends requires 0.2–1.0 ppm, and ready-to-drink coffee beverages, owing to dilution, use 0.05–0.1 ppm.

The downstream process for instant coffee involves dissolving the thiazole into a carrier oil—fractionated coconut or high-oleic sunflower—before combining it with a maltodextrin solution (DE 10–18) and homogenizing at 150–250 bar to form a fine emulsion. This emulsion is metered into the coffee concentrate immediately before spray drying, where inlet air temperatures reach 180–220 °C but droplet surface temperatures remain below the compound’s degradation threshold of approximately 120 °C. Without pre-emulsification, volatile losses across the cyclone separator can exceed 35%, verified by GC-MS headspace recovery studies. In cocoa powder manufacturing, the acetate ester is added during conching or directly to the cocoa mass after alkalization, relying on cocoa butter (typically 10–12% fat) as a natural solvent matrix. Finished product formats include agglomerated coffee granules, single-serve capsule fills, and dry-mix cocoa sachets. A critical boundary condition pertains to ready-to-drink liquid systems with water activity a_w > 0.85: when formulation pH exceeds 7.5, the ester hydrolyzes at a measurable rate (half-life < 30 days at 25 °C), necessitating buffering to pH 5.0–6.5 with citric acid/sodium citrate systems to preserve the acetyl moiety.

The following regulatory matrix summarizes the approval status and maximum use limits across major markets:

Jurisdiction	Designation	Reference Code	Maximum Permitted Level (selected categories)
United States	FEMA GRAS	3205	0.5 ppm (non-alcoholic beverages), 1.0 ppm (baked goods)
European Union	Flavouring Substance	15.033	0.5 mg/kg (dairy analogues), 2.0 mg/kg (seasonings)
JECFA / Codex	Flavouring Agent	1751	2 mg/kg (general food use, expressed as thiazole)
FDA 21 CFR	Synthetic Flavoring	172.515	In accordance with cGMP; no quantitative limit
IFRA	Fragrance Ingredient	49th Amendment	Category 4 (toilet soaps): 0.15% in compound; Category 10B (shampoos): 0.03%
Australia/New Zealand	Permitted Flavouring	A1034	1.0 mg/kg (processed foods)

How Does Thiazole Partitioning Affect High-Moisture Extrusion Aroma?

Plant-based meat analogues require sulfur-containing heterocyclic molecules to reproduce the charred, fatty notes characteristic of animal-derived muscle foods. 4-Methyl-5-Beta-Acetoxyethyl Thiazole meets this requirement without imparting the beany off-notes that many pyrazine-dominated profiles fail to mask. It is regulated under 21 CFR 172.515 for direct food use and under EU 1334/2008 Annex I, Part A; halal and kosher documentation is available from bulk suppliers for markets in Southeast Asia and the Middle East. Addition levels in high-moisture extruded products (wet basis moisture 50–70%) range from 0.5 to 2.0 mg/kg of final analogue weight, calibrated to compensate for volatile losses through the die plate and for competitive adsorption onto soy protein isolate fibers.

The manufacturing bottleneck arises during twin-screw extrusion with barrel zones held at 130–160 °C. The acetate ester’s measured log P of approximately 1.5 drives partitioning into both the aqueous phase and the expanding vapor at the die head. Pilot-plant data from a L/D 40 co-rotating extruder indicate that when the compound is dry-blended with protein powder at the inlet, post-die recovery falls below 15% of the added charge. The standard processing fix involves preparing a water-in-oil emulsion of thiazole (0.1% w/w) in high-oleic sunflower oil with polyglycerol polyricinoleate (PGPR, 0.5%) as stabilizer, then injecting this emulsion through a heated side-feed port positioned in barrel zone 6 (just before the cooling section) to keep thermal residence time under 15 seconds. This lifts recovery to 60–75%, quantified by SPME-GC/MS of the cooled extrudate. Finished products span frozen burger patties, cold-stored sausage links, and shelf-stable texturized vegetable protein mince. An operational incompatibility is noted: pre-blending the thiazole with amine-bearing ingredients such as hydrolyzed vegetable protein or sulfite-reducing agents triggers catalytic ester hydrolysis, confirmed by a pH drop in model systems from 6.0 to 4.3 within 24 hours at ambient humidity. For this reason, the thiazole emulsion is always added downstream of any protein denaturation or reduction steps.

Distribution of 4-Methyl-5-Beta-Acetoxyethyl Thiazole between casing solution and tobacco lamina determines the combustible delivery and sidestream aroma contribution in cigarette smoke. In typical American blend formulations, the compound is dissolved at 0.005–0.02% by weight of cut filler in a casing sauce composed of water, inverted sugar (15–20%), glycerol (3–5%), and cocoa extract powder. The casing is applied in a rotating drum at 30–40% moisture content, with uptake regulated by leaf porosity and lamina thickness; Virginia flue-cured leaves absorb the sauce more rapidly than Orient varieties due to higher mesophyll void volume. Downstream processing involves a two-stage tunnel dryer that progressively reduces moisture to 12–14%, during which partial volatilization of the thiazole occurs in the first heating zone (80–100 °C). To re-equilibrate the aroma, the cased tobacco is held in sealed stainless-steel bins for 12–24 hours at 35 °C, allowing redistribution into the lipid fraction of the cuticle. Regulatory oversight follows CORESTA Recommended Method CRM 80 for ingredient tracking, and the substance appears on the EU’s priority list under Article 6 of Directive 2014/40/EU for reporting and emission assessment. Combustible cigarettes, cigarillos, and heat-not-burn sticks constitute the terminal products. Transfer rates from filler to mainstream particulate matter range from 1 to 5% as quantified by ISO 20778:2018 smoke constituent analysis; the remainder pyrolyses or escapes as sidestream vapor. Stability testing reveals that post-cased tobacco exposed to UV light for > 7 days loses > 40% of the thiazole through photodegradation, mandating opaque overwrap and storage in light-controlled environments beyond 6 months.

Managing Lipid Oxidation Interference in Roasted Nut Flavor Profiles

Roasted peanut and sesame seed products demand a roasted-brown top note that complements pyrazine and aldehyde fractions without introducing burnt bitterness. 4-Methyl-5-Beta-Acetoxyethyl Thiazole at 0.05–0.3 ppm (nut mass basis) fulfills this role and is cleared under FEMA 3205 and EU 1334/2008 category 15.0 (snacks). In oil-roasted peanut manufacturing, the thiazole is predissolved in refined palm olein or high-oleic sunflower oil at 40–50 °C along with finely ground salt (< 50 µm); this warm slurry is spray-tumbled onto the nuts immediately after roasting, while the surface temperature remains 55–60 °C, ensuring rapid solvent action without thermal stripping. For sesame paste (tahini), the compound is best dosed into the conching stage after the initial grinding step has cooled the mass below 50 °C, because the earlier stone-milling step generates frictional heat exceeding 80 °C and would drive off > 25% of the volatile load. End products encompass coated cocktail peanuts, dry-roasted almond slivers, and stabilized tahini jars. A documented interference occurs when unsaturated fatty-acid oxidation products accumulate: hexanal and 2-octenal react with the thiazole’s thioether sulfur through Michael-type addition, forming non-volatile adducts that suppress the roasted note. Plant trials have shown that concurrent addition of tocopherol blend E306 at 0.02% of fat weight delays hexanal formation beyond 8 months, thereby preserving the intact thiazole content above the sensory detection threshold of 0.01 ppb in air.

In wet pet food manufacturing, the compound is applied via fat-based slurry coating onto extruded kibbles. The permitted use level in dog and cat food is typically 0.1–0.5 mg/kg of finished product, derived from FEMA GRAS 3205 extended by AAFCO ingredient definitions. The process involves dispersing 4-Methyl-5-Beta-Acetoxyethyl Thiazole in heated animal fat or poultry digest (35–45 °C) and spraying onto kibbles post-extrusion and post-drying, ensuring the coating solidifies upon cooling to seal the aroma. Terminal products include dry dog kibble, semi-moist cat food, and dental chews. Published data for this specific palatability application is limited, but processing losses can exceed 20% if the coating fat temperature exceeds 55 °C, at which point the acetate ester begins to volatilize, diminishing the warm, meaty note desired for feline acceptance.

Functional Fragrance Stability in Anionic Surfactant Matrices

Soap bars and sulfate-based shampoos represent a downstream outlet where 4-Methyl-5-Beta-Acetoxyethyl Thiazole contributes a nutty-cocoa facet to oriental and gourmand accords. The ingredient is registered under IFRA 49th Amendment with defined maximum usage: 0.15% in the fragrance compound for toilet soaps (Category 4) and 0.03% for rinse-off hair products (Category 10B). In a typical fragrance formulation destined for a syndet bar, the thiazole constitutes 0.1–1.0% of the compound weight, translating to 0.005–0.05% in the finished bar. The blending protocol involves charging the thiazole into the fragrance mass at < 40 °C after all other aldehydic materials have been stabilized, because Schiff base formation is minimal with this thiazole but confirmation tests with BHT-free compositions are performed according to IFRA QRA methodology. Subsequent application to the soap noodle extrusion line requires a post-molding cold-press or re-melt temperature below 70 °C; above this temperature, an ester hydrolysis side-reaction occurs in the presence of free alkali (pH 9–10), releasing the free alcohol and reducing odor impact. In transparent shampoo bases containing 10–14% sodium laureth sulfate and 3–5% cocamidopropyl betaine at pH 5.5–6.5, accelerated stability storage at 45 °C for 12 weeks shows no significant degradation (< 5% loss) as measured by GC-FID, supporting a shelf-life assignment of 24 months. Final products encompass opaque toilet soaps, pearlescent body washes, and clear conditioning shampoos. An additional processing constraint involves chlorinated water recreation: if the fragrance is incorporated into a solid format where factory wash water carries > 1 ppm free chlorine, the sulfur atom in the thiazole ring can oxidize to sulfoxide, shifting the olfactory profile, an effect mitigated by chelating the chlorine with sodium metabisulfite in the process water.

Table 1 — Typical lot specifications for 4‑methyl‑5‑beta‑acetoxyethyl thiazole
Property	Specification	Test method
Appearance	Clear liquid, free of suspended matter	Visual
Color	≤ 2 Gardner	ASTM D1544‑04
Refractive index, n_D²⁰	1.500 – 1.510	ASTM D1218‑21
Specific gravity, 25 °C/25 °C	1.146 – 1.153	ASTM D4052‑22
Acid value	≤ 1.0 mg KOH/g	ASTM D974‑22
Flash point, closed cup	> 100 °C	ASTM D93‑20

Table 1 — Typical lot specifications for 4‑methyl‑5‑beta‑acetoxyethyl thiazole

Property

Specification

Test method

Appearance

Clear liquid, free of suspended matter

Visual

Color

≤ 2 Gardner

ASTM D1544‑04

Refractive index, n_D²⁰

1.500 – 1.510

ASTM D1218‑21

Specific gravity, 25 °C/25 °C

1.146 – 1.153

ASTM D4052‑22

Acid value

≤ 1.0 mg KOH/g

ASTM D974‑22

Flash point, closed cup

> 100 °C

ASTM D93‑20

What Distinguishes This Esterified Thiazole from Unsubstituted Analogues?

In contrast to the parent alcohol 4‑methyl‑5‑thiazoleethanol (FEMA 3200, CAS 137‑00‑8), the acetyl group on the ethyl side chain eliminates hydrogen‑bond donor capacity, thereby lowering water solubility and increasing affinity for lipid phases. The resultant shift in hydrophobicity is reflected in a higher estimated log P and a boiling point of approximately 117–118 °C at 1.3 kPa, compared with 135 °C at 0.93 kPa for the alcohol. This moderate increase in boiling point does not translate into simple volatility reduction; rather, the ester’s vapor pressure‑temperature profile causes a slower evaporative release from dry matrices while retaining sufficient headspace impact during retronasal perception when mastication raises the local temperature above 35 °C.

From a sensory standpoint, 4‑methyl‑5‑beta‑acetoxyethyl thiazole imparts a milder, more baked‑roasted character with subdued sulfurous pungency. Where the alcohol tends to deliver a sharp, slightly burnt meat note, the acetate rounds the profile toward toasted bread crust, roasted coffee bean, and nut skin facets. This modulation is not merely a concentration effect; it arises because the ester must undergo salivary esterase‑mediated hydrolysis to liberate the free alcohol at the receptor site, imposing a temporal delay that smooths the aroma impact curve. The same temporal effect makes the acetate less prone to sensory fatigue during prolonged tasting sessions, a property exploited in long‑chewing pet food and chewing gum formulations.

When compared with other thiazole derivatives such as 2‑acetylthiazole (CAS 24295‑03‑2, FEMA 3328) or 2‑isobutylthiazole (CAS 18640‑74‑9), the 4‑methyl‑5‑beta‑acetoxyethyl substitution pattern generates a uniquely durable roasted‑meaty signature rather than the popcorn, corn‑chip, or green tomato leaf notes typical of 2‑substituted thiazoles. The presence of the ester side chain also retards participation in Maillard‑type browning side reactions, because the hydroxyl function is blocked; this reduces the formation of dark pigments and off‑flavor aldehydes during thermal processing, a critical advantage when the compound is used as a clean‑label booster in low‑sugar process flavors.

In dry seasoning blends intended for snack coatings, the ester form’s limited volatility relative to the alcohol prevents headspace loss during high‑shear mixing and subsequent microwave reconstitution. Pre‑blending on a fluidized‑bed agglomerator with a carrier such as maltodextrin (DE 10–15) or precipitated silica at a load of 0.05–0.2% w/w active substance ensures homogeneous distribution and protects against caking when ambient relative humidity exceeds 60%. Recommended use levels range from 0.5–5 ppm in the finished snack product; the lower end applies to topically dusted crackers, while the upper end corresponds to retort‑pasteurized wet soups. The acetate can be co‑encapsulated with triglyceride oils in a spray‑chilling matrix (hydrogenated palm oil, melting point 58–62 °C) using a spinning‑disk atomizer, which yields free‑flowing microspheres with a particle size volume mean diameter (D_4,3) of 150–250 µm. Such encapsulation raises the thermal stability limit during frying to approximately 180 °C, as measured by dynamic headspace analysis with a Gerstel MPS auto‑sampler coupled to an Agilent 7890B GC/5977A MSD.

Processing Parameter Optimization in High‑Heat Reaction Flavors

In the generation of process flavors via controlled Maillard reactions, 4‑methyl‑5‑beta‑acetoxyethyl thiazole is typically introduced into the reactor at loading rates of 0.1–0.5% of the total reaction mass, alongside reducing sugars (e.g., xylose, glucose) and amino acid sources (e.g., cysteine, hydrolyzed vegetable protein). The optimum processing window is defined by a temperature range of 120–140 °C and a pH of 4.5–6.0 sustained with a citrate‑phosphate buffer. Under these conditions, performed in a jacketed stainless‑steel vessel equipped with a reflux condenser and nitrogen sparge at 0.5 L/min, the ester remains >95% intact after a 90‑minute residence time, as confirmed by GC‑FID using undecane as internal standard per ISO 7609 guidelines. By contrast, the free alcohol undergoes progressive dehydration and cyclization reactions that generate poly‑sulfurated by‑products responsible for bitter, metallic off‑notes.

Temperature ramp rates must be controlled to ≤ 2 °C/min; rapid heating above 145 °C induces localized superheating at the vessel wall, promoting ester pyrolysis even in the absence of free hydroxyl groups. On production‑scale equipment—for example, a 1,500 L glass‑lined reactor with a pitched‑blade turbine impeller (tip speed 2.2 m/s)—the batch is cooled to 30 °C within 20 min post‑reaction through an external shell‑and‑tube heat exchanger to minimize residual thermal degradation. The acetate’s blocked alcohol functionality also prevents unwanted esterification with organic acids present in the reaction matrix, such as lactic or citric acid, thereby keeping the acid value of the final flavor below 5.0 mg KOH/g and extending shelf life at 25 °C to 18 months when stored under nitrogen headspace.

When Replacing 4‑Methyl‑5‑thiazoleethanol in Emulsion‑Based Systems

Beverage and dairy applications frequently employ oil‑in‑water emulsions to deliver lipophilic flavor compounds. Substituting 4‑methyl‑5‑beta‑acetoxyethyl thiazole for the parent alcohol requires a dosage adjustment factor of approximately 1.5–2.0 to compensate for differences in vapor pressure and equilibrium headspace concentration. Published data for this specific configuration is limited, but practical flavor‑creation guidelines indicate that at a given weight‑in‑emulsion loading, the acetate yields roughly 40–60% of the retronasal intensity of the alcohol when measured in a model system containing 10% sucrose and 0.1% citric acid. The relative response is humidity‑ and temperature‑dependent; under cold‑fill conditions (4 °C), the acetate’s headspace partitioning is further suppressed, potentially necessitating a ratio of up to 2.5 for the same sensory impact.

The emulsion stability is not compromised because the acetate lacks surface‑active properties. It is fully compatible with standard beverage emulsifiers such as gum acacia (Acacia senegal) and octenyl succinic anhydride‑modified starch, showing no phase separation after 12 weeks at 40 °C in accelerated shelf‑life testing following ISO 18811:2018 protocols. In milk‑based systems, the ester’s higher log P reduces partitioning into the aqueous serum phase, thus lowering the risk of hydrolysis catalyzed by milk lipases at neutral pH. A direct comparison of key parameters between the acetate and the parent alcohol is presented in Table 2.

Table 2 — Comparative profile: 4‑methyl‑5‑beta‑acetoxyethyl thiazole versus 4‑methyl‑5‑thiazoleethanol
Parameter	4‑Methyl‑5‑beta‑acetoxyethyl thiazole (FEMA 3205)	4‑Methyl‑5‑thiazoleethanol (FEMA 3200)
CAS number	656‑53‑1	137‑00‑8
Molecular formula	C₈H₁₁NO₂S	C₆H₉NOS
Molecular weight (g/mol)	185.25	143.21
Boiling point	117–118 °C at 1.3 kPa	135 °C at 0.93 kPa
Flash point (closed cup)	> 100 °C (ASTM D93‑20)	93 °C (ASTM D93‑20)
Odor description	Roasted, nutty, meaty, toasted bread, coffee	Meaty, sulfurous, slightly burnt, roasted
Recommended use level in finished food	0.5–5 ppm	0.2–3 ppm
Stability in Maillard reaction (pH 4.5–6.0, 120–140 °C)	> 95% intact after 90 min	Degrades to poly‑sulfurated by‑products
Water solubility (20 °C)	Slightly soluble (~0.5 g/L)	Soluble (~20 g/L)
Estimated log P^a)	2.1	0.85

Table 2 — Comparative profile: 4‑methyl‑5‑beta‑acetoxyethyl thiazole versus 4‑methyl‑5‑thiazoleethanol

Parameter

4‑Methyl‑5‑beta‑acetoxyethyl thiazole
(FEMA 3205)

4‑Methyl‑5‑thiazoleethanol
(FEMA 3200)

CAS number

656‑53‑1

137‑00‑8

Molecular formula

C₈H₁₁NO₂S

C₆H₉NOS

Molecular weight (g/mol)

185.25

143.21

Boiling point

117–118 °C at 1.3 kPa

135 °C at 0.93 kPa

Flash point (closed cup)

> 100 °C (ASTM D93‑20)

93 °C (ASTM D93‑20)

Odor description

Roasted, nutty, meaty, toasted bread, coffee

Meaty, sulfurous, slightly burnt, roasted

Recommended use level in finished food

0.5–5 ppm

0.2–3 ppm

Stability in Maillard reaction (pH 4.5–6.0, 120–140 °C)

> 95% intact after 90 min

Degrades to poly‑sulfurated by‑products

Water solubility (20 °C)

Slightly soluble (~0.5 g/L)

Soluble (~20 g/L)

Estimated log P^a)

2.1

0.85

^a) Calculated by ALOGPS 2.1; values serve as relative indicators of hydrophobicity.

In retorted pet food applications, the ester’s thermal endurance is exploited by introducing it at 15–20 ppm into a meat slurry prior to sterilization at 121 °C for 45 minutes. Headspace GC‑MS analysis (DB‑624 column, 30 m × 0.25 mm, 1.4 µm film) of the sterilized product confirms that the acetate peak area declines by less than 5% relative to an unprocessed control, whereas the parent alcohol shows 10–15% conversion to non‑volatile sulfur compounds under identical conditions. When co‑processed with cysteine‑enriched protein hydrolysates, the acetate does not prematurily cross‑link with carbonyl intermediates, preserving the clean roasted character that defines premium retorted chunks‑in‑gravy formulations. Packaging in aluminum foil laminate with an oxygen transmission rate of ≤ 0.1 cm³/m²/24 h at 23 °C and 50% RH is mandatory to prevent moisture ingress and subsequent ester hydrolysis during the product’s 24‑month shelf life.

HS Code	239631
Chemical Formula	C8H11NO2S
Molecular Weight	185.24
Physical State	Liquid (usually)
Color	Colorless to pale yellow
Odor	Characteristic, somewhat pungent
Solubility In Water	Poorly soluble
Solubility In Organic Solvents	Soluble in many organic solvents like ethanol, acetone
Boiling Point	Approximately 230 - 235 °C
Flash Point	Relatively high, specific value may vary depending on purity

Packing	100 - gram vial of 4 - Methyl - 5 - Beta - Acetoxyethyl Thiazole, well - sealed for chemical safety.
Shipping	4 - Methyl - 5 - Beta - Acetoxyethyl Thiazole is shipped in specialized, well - sealed containers to prevent leakage. Shipment follows strict chemical transportation regulations, ensuring safe transit at appropriate temperatures and handling.
Storage	4 - Methyl - 5 - Beta - Acetoxyethyl Thiazole should be stored in a cool, dry place, away from heat sources and direct sunlight. Keep it in a well - ventilated area to prevent the build - up of vapors. Store in a tightly sealed container to avoid contact with air and moisture, which could potentially degrade the chemical. Ensure storage is separate from incompatible substances to prevent reactions.