(Z+E)-5-ethyl-4-methyl-2-(2-butyl) thiazoline

(Z+E)-5-ethyl-4-methyl-2-(2-butyl) thiazoline is a sulfur-containing heterocyclic compound characterized by a molecular formula of C₁₀H₁₉NS and a molecular weight of approximately 185.33 g/mol. This compound exists as cis and trans isomers and is commonly encountered under various names including 5-ethyl-2,5-dihydro-4-methyl-2-(1-methylpropyl)thiazole. It is notable for its distinct meaty and nutty odor profile reminiscent of cooked roasted foods. The compound is typically synthesized and utilized as a flavoring agent, primarily in food products, and is indexed in chemical databases such as PubChem. Its source derives from synthetic chemical processes targeting heterocyclic thiazoline structures, leveraged for their aromatic contribution to complex flavor formulations.

(Z+E)-5-ethyl-4-methyl-2-(2-butyl) thiazoline does not commonly occur naturally but is synthetically produced to replicate savory and roasted meat aromas in food applications. It is employed primarily as a flavoring agent to enhance and mimic meat flavors in an array of food products including baked goods, beverages, confectionery, and savory items. Usage considerations are guided by FEMA (US) standards where it holds FEMA number 4318 and is recognized as generally safe within defined limits. Its application spans both natural and processed food matrices to impart a characteristic meaty aroma and deepen flavor complexity. Regulatory evaluations and flavoring assessments by organizations such as JECFA (International) affirm its role and acceptable exposure levels in food flavor development.

(Z+E)-5-ethyl-4-methyl-2-(2-butyl) thiazoline presents as a compound with moderate volatility, a boiling point in the range of 238 to 239°C at standard atmospheric pressure, and a relatively low vapor pressure of 0.064 mmHg at 25°C. It has a specific gravity of approximately 0.95 to 0.956 at 25°C and a refractive index between 1.487 and 1.493 at 20°C. With an estimated log P value near 3.9, it exhibits moderate lipophilicity impacting solubility and partitioning behavior critical to formulation. Its water solubility is low, estimated at about 1.383 mg/L at 25°C. The relatively high flash point of 209°F (approximately 98°C) indicates a notable degree of thermal stability. These physicochemical characteristics influence its handling, application concentration, and interaction within flavor matrices.

(IUPAC):	Atomic Weights of the Elements 2011 (pdf)
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(IUPAC):	Periodic Table of the Elements
FDA Substances Added to Food (formerly EAFUS):	View
HMDB (The Human Metabolome Database):	HMDB32201
FooDB:	FDB009182
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Safety information

Hazards identification
Classification of the substance or mixture
GHS Classification in accordance with 29 CFR 1910 (OSHA HCS)
None found.
GHS Label elements, including precautionary statements
Pictogram
Hazard statement(s)
None found.
Precautionary statement(s)
None found.
Oral/Parenteral Toxicity:
Not determined
Dermal Toxicity:
Not determined
Inhalation Toxicity:
Not determined

Safety in use information

Category:
flavoring agents
Recommendation for (Z+E)-5-ethyl-4-methyl-2-(2-butyl) thiazoline usage levels up to:
	not for fragrance use.
Maximised Survey-derived Daily Intakes (MSDI-EU):		0.012 (μg/capita/day)
Maximised Survey-derived Daily Intakes (MSDI-USA):		ND (μg/capita/day)
Modified Theoretical Added Maximum Daily Intake (mTAMDI):		160 (μg/person/day)
Threshold of Concern:		90 (μg/person/day)
Structure Class:		III
Use levels for FEMA GRAS flavoring substances on which the FEMA Expert Panel based its judgments that the substances are generally recognized as safe (GRAS).
The Expert Panel also publishes separate extensive reviews of scientific information on all FEMA GRAS flavoring substances and can be found at FEMA Flavor Ingredient Library
publication number: 23
Click here to view publication 23
		average usual ppm	average maximum ppm
baked goods:		0.40000	2.00000
beverages(nonalcoholic):		0.20000	1.00000
beverages(alcoholic):		-	-
breakfast cereal:		0.40000	1.00000
cheese:		-	-
chewing gum:		-	-
condiments / relishes:		-	-
confectionery froastings:		0.40000	2.00000
egg products:		-	-
fats / oils:		0.20000	1.00000
fish products:		0.10000	0.40000
frozen dairy:		-	-
fruit ices:		0.40000	2.00000
gelatins / puddings:		-	-
granulated sugar:		-	-
gravies:		-	-
hard candy:		-	-
imitation dairy:		-	-
instant coffee / tea:		-	-
jams / jellies:		-	-
meat products:		0.10000	0.40000
milk products:		0.40000	2.00000
nut products:		0.40000	2.00000
other grains:		-	-
poultry:		-	-
processed fruits:		0.30000	1.50000
processed vegetables:		0.30000	1.50000
reconstituted vegetables:		-	-
seasonings / flavors:		-	-
snack foods:		-	-
soft candy:		-	-
soups:		0.20000	1.00000
sugar substitutes:		-	-
sweet sauces:		-	-
Food categories according to Commission Regulation EC No. 1565/2000 (EC, 2000) in FGE.06 (EFSA, 2002a). According to the Industry the "normal" use is defined as the average of reported usages and "maximum use" is defined as the 95th percentile of reported usages (EFSA, 2002i).
Note: mg/kg = 0.001/1000 = 0.000001 = 1/1000000 = ppm.
		average usage mg/kg	maximum usage mg/kg
Dairy products, excluding products of category 02.0 (01.0):		0.40000	2.00000
Fats and oils, and fat emulsions (type water-in-oil) (02.0):		0.20000	1.00000
Edible ices, including sherbet and sorbet (03.0):		0.40000	2.00000
Processed fruit (04.1):		0.30000	1.50000
Processed vegetables (incl. mushrooms & fungi, roots & tubers, pulses and legumes), and nuts & seeds (04.2):		-	-
Confectionery (05.0):		0.40000	2.00000
Chewing gum (05.3):		-	-
Cereals and cereal products, incl. flours & starches from roots & tubers, pulses & legumes, excluding bakery (06.0):		0.20000	1.00000
Bakery wares (07.0):		0.50000	2.00000
Meat and meat products, including poultry and game (08.0):		0.10000	0.40000
Fish and fish products, including molluscs, crustaceans and echinoderms (MCE) (09.0):		0.10000	0.40000
Eggs and egg products (10.0):		-	-
Sweeteners, including honey (11.0):		-	-
Salts, spices, soups, sauces, salads, protein products, etc. (12.0):		0.20000	1.00000
Foodstuffs intended for particular nutritional uses (13.0):		0.40000	2.00000
Non-alcoholic ("soft") beverages, excl. dairy products (14.1):		0.20000	1.00000
Alcoholic beverages, incl. alcohol-free and low-alcoholic counterparts (14.2):		0.40000	2.00000
Ready-to-eat savouries (15.0):		1.00000	5.00000
Composite foods (e.g. casseroles, meat pies, mincemeat) - foods that could not be placed in categories 01.0 - 15.0 (16.0):		0.20000	1.00000

Safety references

European Food Safety Athority(EFSA):Flavor usage levels; Subacute, Subchronic, Chronic and Carcinogenicity Studies; Developmental / Reproductive Toxicity Studies; Genotoxicity Studies...

European Food Safety Authority (EFSA) reference(s):

Flavouring Group Evaluation 93 (FGE.93): Consideration of sulphur heterocyclic evaluated by JECFA (68th meeting) structurally related to thiazoles, thiophene, thiazoline and thienyl evaluated by EFSA in FGE.21Rev1 (2009) View page or View pdf

Statement on List of Representative Substances for Testing. The current Statement lays down a list of substances in sub-groups with representative substances for which additional data are required prior to their evaluation through the Procedure (Regulation (EC) No 1565/2000). View page or View pdf

Scientific Opinion on Flavouring Group Evaluation 93, Revision 1 (FGE.93Rev1): Consideration of sulphur containing heterocyclic compounds evaluated by JECFA (68th meeting) structurally related to thiazoles, thiophene, thiazoline and thienyl derivatives evaluated by EFSA in FGE.21Rev3 View page or View pdf

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EPA ACToR:Toxicology Data

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Laboratory Chemical Safety Summary :73456809

National Institute of Allergy and Infectious Diseases:Data

2-(butan-2-yl)-5-ethyl-4-methyl-4,5-dihydro-1,3-thiazole

Chemidplus:0083418546