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L-cysteine

CAS Number
52-90-4
EC Number
200-158-2
Chemical Formula
C3H7NO2S
Molecular Weight
121.16 g/mol

Description

L-Cysteine (CAS 52-90-4 ), also designated E920 in food applications, is a sulfur-containing amino acid sourced through fermentation or protein hydrolysis. In food and pharmaceutical manufacturing, it functions primarily as a dough conditioner and antioxidant. It serves as a precursor in flavor and nutrient synthesis. In commercial baking, E920 reduces mixing time and improves dough extensibility, making it a standard processing aid in bread, crackers, and pizza bases. Pharmaceutical and nutraceutical manufacturers use this amino acid as a building block for glutathione synthesis and in amino acid infusion formulations. Personal care formulators incorporate it into hair treatment products. It is used in keratin-based straightening and conditioning systems where it modifies disulfide bonds in hair protein. In flavor production, Cys reacts with sugars under heat to generate meat-like and savory Maillard compounds. This chemical qualifies under FEMA 3263 for use in reaction flavor systems. The product is supplied as a white crystalline powder, available in both free base and hydrochloride monohydrate forms. Recognized grades include USP , Ph.Eur. , FCC , and food-grade. The hydrochloride salt is the most commercially prevalent form due to its stability and ease of handling in industrial settings. Bulk supply is standard for industrial food and pharma applications. Smaller quantities are available for specialty formulation, ensuring compliance with BP , EP , and ACS standards where required. Contact us for supply of L-cysteine Request Quote

Other Names (Synonyms)

(2R)-2-ammonio-3-sulfanylpropanoate | L-Zystein | L-Cystein | L-Cys | L-2-Amino-3-mercaptopropionic acid | L-2-Amino-3-mercaptopropanoic acid | L-2-Amino-3-mercaptopropanoate | Half-cystine | Cys | E920

Key Technical Features

  • High Purity Grade standard
  • Consistent Batch Quality
  • Full Regulatory & REACH Support
  • Global Logistics Network enabled

Physical Properties

Melting Point240 °C (decomp)
Boiling Point293.9±35.0 °C(Predicted)
Density1.6666 g/cm³ @ Temp: 45.00 °C
AppearanceWhite crystalline powder
ColorWhite
Odorsulfury
FormSolid
Water Solubility280 g/L (25 ºC)
Refractive Index8.8 ° (C=8, 1mol/L HCl)
pH4.5-5.5 (100g/l, H2O, 20℃)
Log P-2.49

Safety & Handling

Warning
GHS07· Irritant

Hazard Statements

H302Harmful if swallowed
H315Causes skin irritation
H319Causes serious eye irritation
H335May cause respiratory irritation

Precautionary Statements

P261Avoid breathing dust/fume/gas/mist/vapours/spray.
P264Wash … thoroughly after handling.
P270Do not eat, drink or smoke when using this product.
P271Use only outdoors or in a well-ventilated area.
P280Wear protective gloves/protective clothing/eye protection/face protection.
P319Get medical advice/attention if you feel unwell.
P321Specific treatment (see … on this label).
P330Rinse mouth.
P405Store locked up.
P501Dispose of contents/container in accordance with local regulations.
P265Wash … thoroughly after handling.
P317Get emergency medical help.
P352IF ON SKIN: Wash with plenty of water.
P340IF INHALED: Remove person to fresh air and keep comfortable for breathing.
P317Get emergency medical help.
P317If eye irritation persists: Get medical advice/attention. Get emergency medical help.
P364Take off contaminated clothing and wash it before reuse.
P233Store in a well-ventilated place. Keep container tightly closed.
P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.

Trade & Regulatory

HS Code29309012
Storage Class11 - Combustible Solids
WGK (Germany)3