Cysteine

Cysteine is a sulphur-containing amino acid important in protein structure, where its thiol group forms disulfide bonds that stabilize folded proteins and build texture in foods like bread dough and egg gels. It acts as an antioxidant precursor in the body, supporting glutathione synthesis. In processing, cysteine and its hydrochloride salt are used as dough conditioners to relax gluten, and it contributes meaty, sulphurous notes to savoury flavourings through Maillard reactions. It is classified as semi-essential, since the body can make it from methionine.