Overview
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.
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Physical Properties
| Melting Point | 240 °C (decomp) |
| Boiling Point | 293.9±35.0 °C(Predicted) |
| Density | 1.6666 g/cm³ @ Temp: 45.00 °C |
| Appearance | White crystalline powder |
| Color | White |
| Odor | sulfury |
| Form | Solid |
| Water Solubility | 280 g/L (25 ºC) |
| Refractive Index | 8.8 ° (C=8, 1mol/L HCl) |
| pH | 4.5-5.5 (100g/l, H2O, 20℃) |
| Log P | -2.49 |
Safety & Handling
Warning GHS07 Hazard Statements H302 Harmful if swallowed H315 Causes skin irritation H319 Causes serious eye irritation H335 May cause respiratory irritation Precautionary Statements P261 Avoid breathing dust/fume/gas/mist/vapours/spray. P264 Wash … thoroughly after handling. P270 Do not eat, drink or smoke when using this product. P271 Use only outdoors or in a well-ventilated area. P280 Wear protective gloves/protective clothing/eye protection/face protection. P319 Get medical advice/attention if you feel unwell. P321 Specific treatment (see … on this label). P330 Rinse mouth. P405 Store locked up. P501 Dispose of contents/container in accordance with local regulations. P264+P265 Wash … thoroughly after handling. P301+P317 Get emergency medical help. P302+P352 IF ON SKIN: Wash with plenty of water. P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing. P332+P317 Get emergency medical help. P337+P317 If eye irritation persists: Get medical advice/attention. Get emergency medical help. P362+P364 Take off contaminated clothing and wash it before reuse. P403+P233 Store in a well-ventilated place. Keep container tightly closed. P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
Trade & Regulatory
| HS Code | 29309012 |
| Storage Class | 11 - Combustible Solids |
| WGK (Germany) | 3 |
Other Names
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Chemical Properties
- CAS Number
- 52-90-4
- EC Number
- 200-158-2
- Mol. Weight
- 121.16
- HS Code
- 29309012
- Category
- Vitamins & Nutrients