L-Cysteine
What it does
Dough conditioner/improver in bread and pastries.
How it's made
Made by hydrolysis (traditionally from hair/feathers; now often fermentation).
L-Cysteine is an amino acid used as a flour treatment agent and dough conditioner; it relaxes and softens dough, making it easier to work and shape, and speeds up mixing. It is particularly used in products like pizza bases, pastries and some breads where an extensible dough is wanted.
It is produced either by fermentation using microbes engineered or selected to make L-cysteine, or by extraction and hydrolysis of protein-rich materials. Historically it was obtained by breaking down keratin from sources such as feathers, hair or bristles, though microbial fermentation from plant-based feedstocks is now widely used and preferred, especially for vegetarian products.
The cysteine is purified and crystallised into a white powder. In dough it works by breaking some of the chemical bonds in gluten, which loosens the protein network and makes the dough softer and more stretchy; the source (fermentation versus animal-derived) matters to vegetarian and religious dietary requirements, so it is often specified.
Possible reactions
Generally safe; source (animal/hair vs fermentation) matters for vegans and some faiths.