L-Cysteine Hydrochloride Monohydrate (CAS 7048-04-6) Application 

L-Cysteine hydrochloride monohydrate (L-Cys·HCl·H₂O, CAS 7048-04-6) is a water-soluble salt of the non-essential amino acid L-cysteine. It appears as a white to off-white crystalline powder with a characteristic slight odor and serves as a critical functional ingredient across the food, cosmetic, animal nutrition, and industrial sectors.

Key Applications by Industry

1. Food Industry — Dough Conditioning & Beyond

L-Cysteine hydrochloride monohydrate is globally recognized as food additive E920 and is one of the most important functional ingredients in commercial baking and food processing.

Bakery & Dough Conditioning

Why Manufacturers Choose L-Cysteine HCl Monohydrate？

● Faster mixing cycles reduce energy costs

● Consistent dough handling across batch variations

● Clean-label compatible when declared as E920 or "amino acid (L-cysteine)"

● Effective at low inclusion rates for cost efficiency

2. Cosmetic & Personal Care

L-Cysteine hydrochloride monohydrate is a valued ingredient in hair care, skin care, and anti-aging formulations due to its role as a glutathione precursor and its involvement in collagen synthesis.

3. Animal Feed & Nutrition

The European Food Safety Authority (EFSA) has confirmed L-cysteine hydrochloride monohydrate as a safe sensory additive (flavouring) for all animal species when used in feed.

The additive is incorporated into feed either through premixtures or directly into compound feed and drinking water. EFSA's 2025 safety assessment confirmed no concerns for target species, consumers, or the environment at recommended inclusion levels.

4. Industrial & Other Technical Applications

Beyond food and personal care, L-Cysteine hydrochloride monohydrate finds utility in several technical applications:

Key Purchasing Specifications

Frequently Asked Questions

What is L-Cysteine hydrochloride monohydrate used for in food?

L-Cysteine hydrochloride monohydrate (E920) is primarily used as a dough conditioner and flour treatment agent in commercial baking. It acts as a reducing agent that breaks down gluten disulfide bonds, softening dough and reducing mixing time. This improves machinability in high-speed production lines for bread, crackers, pizza bases, and tortillas. It is also used to prevent enzymatic browning in fresh-cut fruits and vegetables such as avocados, bananas, and potatoes.

Is L-Cysteine hydrochloride monohydrate vegan?

It depends on the production method. Fermentation-derived L-Cysteine (produced using non-animal E. coli strains) is vegan, halal, and kosher compatible. Traditional hydrolysis-sourced L-Cysteine, extracted from duck feathers or animal hair, is not vegan. Buyers seeking plant-based or vegan-compatible products should specifically request fermentation-grade, non-animal source L-Cysteine hydrochloride monohydrate.

What is the difference between L-Cysteine hydrochloride monohydrate and anhydrous?

The key difference is the water of crystallization. Monohydrate (CAS 7048-04-6, C₃H₈ClNO₂S·H₂O) contains one molecule of water per molecule of L-Cysteine HCl, resulting in a molecular weight of 175.63 g/mol and moisture content of 8.0–12.0% on drying. Anhydrous (CAS 52-89-1, C₃H₈ClNO₂S) contains no water of crystallization, with a molecular weight of 157.62 g/mol and moisture content below 0.5%. The monohydrate form is generally more stable during storage and is the preferred grade for food and cosmetic applications.

What are the typical usage levels in bakery applications?

In commercial baking, L-Cysteine hydrochloride monohydrate is typically used at 10–90 ppm (10–90 mg per kg of flour). The exact dosage depends on flour protein content, desired dough extensibility, and production line speed. Higher-protein flours (above 12% protein) may require levels toward the upper end of this range. It is commonly used in combination with ascorbic acid (vitamin C) and enzymes (amylase, xylanase) as part of a complete dough conditioning system.

Is L-Cysteine hydrochloride monohydrate safe for animal feed?

Yes. The European Food Safety Authority (EFSA) confirmed in 2025 that L-cysteine hydrochloride monohydrate is safe as a sensory flavouring additive for all animal species, including poultry, swine, aquaculture, and pets. No safety concerns were identified for target animals, consumers, or the environment at recommended feed inclusion levels.

How can I verify the quality of L-Cysteine hydrochloride monohydrate?

Request a Certificate of Analysis (CoA) from your supplier covering at minimum: assay (≥98.5% for food grade), specific rotation (+5.6° to +6.3°), heavy metals (≤10 ppm Pb), loss on drying (8.0–12.0%), residue on ignition (≤0.10%), and arsenic (≤1 ppm). For food-grade product, also verify the production method (fermentation vs. hydrolysis) and relevant certifications (HALAL, KOSHER, FSSC 22000, Non-GMO).

What is the shelf life and how should it be stored?

L-Cysteine hydrochloride monohydrate has a typical shelf life of 24–36 months when stored in a cool (15–25 °C), dry environment in tightly sealed containers. The product is hygroscopic and will absorb moisture from the air, leading to clumping and potential degradation. Once opened, containers should be resealed promptly. The product is non-hazardous for transport under DOT, ADR, and IMDG regulations.