L-Cysteine | Food, Pharma & Cosmetic Grade Amino Acid Raw Material CAS 52-90-4

Common Challenges When Sourcing L-Cysteine for Overseas Manufacturers

Many raw material purchasers face various risks when buying L-Cysteine.
Ordinary L-Cysteine on the market suffers poor stability. It is prone to oxidation and converts into L-Cystine during long-distance ocean shipping, resulting in reduced raw material activity.
Fluctuations in purity and specifications across different batches may cause unstable finished products and production losses.
Some suppliers cannot provide complete COA, HPLC and MSDS export documents, which may lead to customs clearance delays.
It can be difficult to find reliable manufacturers that support sample provision for formulation research and small trial orders.

L-Cysteine (CAS 52-90-4) is a naturally occurring non-essential sulfur-containing amino acid with active thiol (-SH) groups and unique reducing properties. It is widely used as food additive, pharmaceutical synthetic intermediate, cosmetic raw material and biochemical laboratory reagent.
Free-form L-Cysteine is chemically reactive. It oxidizes easily when exposed to air under neutral or weakly alkaline conditions, while showing better stability in acidic environments. Strict environmental control is required during storage and formulation.

As a professional manufacturer of L-Cysteine via fermentation, we provide targeted solutions to the above procurement pain points.
Oxygen isolation measures are adopted throughout production and packaging to slow down raw material oxidation.
Food grade and pharmaceutical grade are produced on separate independent production lines to ensure consistent specifications batch by batch.
25kg standard export packages are kept in stock all year round. Full sets of test documents are available upon request.
We support sample testing, small trial orders and long-term bulk contracts to lower your cross-border procurement risks.

L-Cysteine Physical & Chemical Specifications

Chinese Name: L-半胱氨酸
English Name: L-Cysteine
CAS No.: 52-90-4
Molecular Formula: C₃H₇NO₂S
Molecular Weight: 121.16
Appearance: Colorless transparent crystals
Isoelectric Point: 5.07
Solubility: Soluble in water, ethanol, acetic acid and ammonia water; Insoluble in benzene, ether, acetone, carbon tetrachloride and ethyl acetate
Decomposition Temperature: 240℃
Stability: Better storage stability under acidic conditions; Easy to oxidize into L-Cystine under neutral or weakly alkaline environment; Nitrogen-sealed storage helps retain thiol activity for longer periods.

Four Core Advantages of Our L-Cysteine

1. High-Activity Free Thiol Group for Stable Production

High-purity free thiol (-SH) structure delivers favorable antioxidant and heavy metal chelating performance.
It inhibits browning in food systems, serves as synthetic raw material for pharmaceuticals, and exerts antioxidant effects in cosmetic formulations, helping reduce losses caused by finished product deterioration.

2. Multi-industry Raw Material to Simplify Your Supply Chain

A single L-Cysteine grade covers four major sectors: food, pharmaceuticals, cosmetics and biochemical laboratories.
You do not need to cooperate with multiple suppliers for different raw materials, saving comprehensive costs on communication, warehousing and logistics management.

3. Dual Grades Available to Meet Global Import Compliance Standards

Separate production lines for food grade and pharmaceutical grade L-Cysteine. Heavy metals and impurities are strictly controlled to meet the access standards for food, personal care and pharmaceutical raw materials in Southeast Asia, Europe, America and other regions, reducing trade risks caused by incomplete qualifications.

4. Stable Factory Supply with Complete Export Documentation

Standardized in-house fermentation workshop with permanent inventory to guarantee stable supply even in peak seasons.
Each batch is attached with COA, HPLC test report and MSDS for customs clearance and internal quality inspection.
Sample evaluation is supported. Bulk orders can be arranged only after formulation tests pass, avoiding losses from large-scale stock procurement.

Main Application Fields of L-Cysteine

Food Industry

Dough improver and fermentation aid for bread and pastry to promote gluten formation and shorten fermentation time.
Antioxidant stabilizer for fruit juice and milk powder to slow down oxidation and discoloration.
Nutritional amino acid additive for animal feed to optimize animal metabolism.

Pharmaceutical Manufacturing

Important amino acid raw material for pharmaceutical synthesis, applicable to various compound amino acid preparations and intermediate synthesis.
Key feedstock for producing derivatives such as Acetylcysteine, widely used in pharmaceutical R&D and manufacturing.

Cosmetics & Personal Care

Key raw material for perm agents, hair care essences and sunscreen products, acting on keratin in hair.
With antioxidant properties, it is widely applied in hair care and skincare formulation development.

Biochemical Laboratories & Research Institutions

Common reducing agent for protein research, cell culture and enzyme activity testing. Long-term supply for university laboratories and biotechnology enterprises.

Quality Control, Export Packaging & Storage Guidelines

1. Quality Control: Multiple sampling tests are implemented for every batch. Purity, moisture and impurities are strictly monitored to minimize batch differences and stabilize production formulas.
2. Standard Export Package: 25kg thick fiber drum with double-layer moisture-proof inner liner, air isolation design suitable for long-distance ocean transportation.
3. Storage Recommendation: Keep sealed in cool and dry warehouse. Avoid neutral or alkaline storage environment. Nitrogen-sealed storage effectively extends the active period of L-Cysteine.

Frequently Asked Questions on L-Cysteine Procurement

Q1: How to choose between L-Cysteine and L-Cysteine Hydrochloride?

A: Free-form L-Cysteine has higher thiol activity and stronger reducing capacity. It suits short-term storage, short-distance transportation and formulations requiring maximum raw material activity, yet it has relatively poor stability and oxidizes easily.
L-Cysteine Hydrochloride features superior chemical stability, ideal for ocean shipment and long-term inventory. Samples of both products are available for comparison. You can select properly based on formulation pH value and storage cycle.

Q2: Can you provide L-Cysteine samples for formulation testing?

A: Samples can be offered. Customers only need to bear international shipping fees. After receiving samples, you can conduct stability and formulation compatibility tests in labs. Bulk order negotiation can start after successful testing to lower trial risks.

Q3: Do the supporting documents meet overseas customs inspection requirements?

A: COA, HPLC purity report and MSDS are fully provided. Specifications can be adjusted according to target market standards to support import and export customs clearance worldwide.

Q4: How long does L-Cysteine take to oxidize and lose activity? How to slow oxidation?

A: When exposed to open air, oxidation into cystine can happen within several days under neutral or alkaline conditions. Longer shelf life can be achieved under sealed acidic storage. Sealed and dark storage is recommended; nitrogen protection is preferred if possible.

Get Your L-Cysteine Procurement Solution

If you are seeking a reliable manufacturer supplying L-Cysteine with stable activity, consistent batch specifications and sustainable supply, there is no need to compare dozens of traders repeatedly.
Contact us to obtain the latest factory quotation and complete product specification sheet. Samples are available for evaluation. Global sea shipment is supported. We supply stable amino acid raw materials for food manufacturers, pharmaceutical factories, cosmetic producers and biotech research institutions.