L-Cysteine Hydrochloride is the ? hydrochloride form of the amino acid ? L-Cysteine (L-cysteine) ? ? (usually the monohydrate of the hydrochloride, chemical formula: C?H?NO?S·HCl·H?O).

The following is the key information about it:

Youdaoplaceholder0 Structure and properties: ?

It is a salt formed by the combination of the amino group (-NH?) in the L-cysteine molecule with hydrochloric acid (HCl).
This form is more ? stable ? than free L-cysteine, has higher ? solubility ? (especially in water), and is also easier to store and transport.
It still retains the core characteristics of L-cysteine: it contains a ? thiol group (-SH) ?, which endows it with ? reducing property ? and the ability to participate in various biochemical reactions (such as forming disulfide bonds and synthesizing glutathione).
Youdaoplaceholder0 Main sources and uses: ?

Youdaoplaceholder0 Food industry (main uses) : ?
Youdaoplaceholder0 Dough conditioner: ? This is its most important application. In baking (especially in the mass production of bread, pizza crusts, etc.) :
Youdaoplaceholder0 reduces dough viscosity: ?, as a reducing agent, breaks disulfide bonds in flour proteins such as glutenin, making the dough softer, more extensible and easier to process (reducing stirring resistance and improving machinability).
Youdaoplaceholder0 Shorten proofing time: ? Promote gluten network reorganization and accelerate fermentation.
Youdaoplaceholder0 To improve the structure of the finished product: ? to make the bread more uniform and fine-textured inside.
Youdaoplaceholder0 Flavor enhancers (mainly found in fruit juice drinks) : ? is used in fruit juices, especially concentrated ones, to prevent Browning (as an antioxidant) and sometimes to enhance the flavor of certain fruits, such as grapefruit.
Youdaoplaceholder0 Nutrient fortifier: ? Added to certain foods as an amino acid supplement.
Youdaoplaceholder0 Medicine & Health Products: ?
Youdaoplaceholder0 Expectorant: ? Its thiol groups break the disulfide bonds of mucin in sputum, reducing its viscosity and making it easier to cough up.
Youdaoplaceholder0 Liver protectant: ? is a key precursor for the synthesis of glutathione (GSH). Glutathione is an important antioxidant and detoxification substance in the human body, which is crucial for protecting liver cells from damage. It is used for the treatment of certain liver diseases (such as alcoholic liver disease and drug-induced liver injury) and as an adjuvant therapy for the rescue of acetaminophen (paracetamol) poisoning.
Youdaoplaceholder0 Antioxidant supplement: ? takes advantage of its reducing property to clear free radicals.
Youdaoplaceholder0 Adjuvant drugs for burn treatment: ? is sometimes used to promote wound healing in patients with severe burns.
Youdaoplaceholder0 Cosmetics & Personal Care: ?
Youdaoplaceholder0 Hair care ingredients: ? claims to maintain the structure of keratin in hair (involving disulfide bonds), enhancing hair strength and resilience. It exists in some hair care products.
Youdaoplaceholder0 Antioxidants: ? Protect the skin from oxidative stress damage.
Youdaoplaceholder0 Whitening ingredient: ? Some studies have explored its potential to inhibit tyrosinase activity (tyrosinase is a key enzyme in melanin synthesis), but the effect and mechanism are not as clear as those of other classic whitening ingredients.
Youdaoplaceholder0 Feed additive: ? as an essential amino acid supplement in animal feed (cysteine is usually classified as a conditionally essential amino acid).
Youdaoplaceholder0 Produced by ?

Traditionally, (hydrolyzed keratin) has mainly been extracted from human hair or animal feathers, but this involves ethical and quality issues.
Youdaoplaceholder0 The most dominant industrial production method nowadays is microbial fermentation (especially baker's yeast fermentation) ?, which is safer, more controllable, more sustainable and compliant with regulatory requirements (particularly in the food and medicine sectors).
Youdaoplaceholder0 Safety and precautions: ?

It is generally safe (GRAS) to use in ? food ? in the prescribed amounts.
Used as a ? medicine ? :
Mild gastrointestinal discomfort (such as nausea, vomiting and diarrhea) may occur.
Too fast intravenous injection speed may cause fluctuations in blood pressure.
Asthma patients or those with a history of bronchospasm should use with caution.
Youdaoplaceholder0 Follow medical advice for pregnant women, breastfeeding women and children. ?
When used as a high-dose dietary supplement of ? ? :
Youdaoplaceholder0 Excessive intake of ? may carry risks (such as cardiovascular effects, insulin resistance, etc.).
Youdaoplaceholder0 Always follow the recommended dosage or use under professional guidance. ?
Youdaoplaceholder0 Contraindications: ? Contraindicated for those allergic to this product; Patients with active peptic ulcers should use with caution or avoid using it.
Youdaoplaceholder0 Summary: ?

L-cysteine hydrochloride is an important commercial amino acid derivative and is widely used due to its stability and good water solubility. It plays a core role in the ? food industry (especially in the improvement of baking dough) ?, and is also of great value in the ? medical field (expectoration, liver protection) ? and ? cosmetics industry (hair care, antioxidation) ?. Its production has generally shifted to safer and more sustainable microbial fermentation methods. When in use, especially as a medicine or high-dose supplement, attention should be paid to its safety and contraindications, and professional guidance should be followed.