Cysteine

Description

Cysteine is an amino acid that contains sulphur. It is semi-essential, i.e., it can be synthesised in the human body through the transformation of methionine, another amino acid that contains sulphur. This capacity does not yet exist in infants, for whom cysteine is an essential amino acid and important for survival.

• Cysteine is a component of many proteins, particularly of plants. It is present in particularly high quantities in keratin, the structural protein found for example in horn, hair and feathers. In cell metabolism, cysteine remains in chemical balance with ist oxidised dipeptide cystine.

Application

Cysteine is applied to a variety of products and thereby fulfils differing technical tasks:

• as a component of many cake mixes and baking components, cysteine is widespread in the manufacture of a wide variety of bread, rolls and baked goods. It raises the ability of dough to "hold gas" and thereby the ability of baked goods to retain a voluminous form for long periods. Additionally, cysteine improves the elasticity and kneadability of dough.
• in the development of flavours and scents associated with meat and with roasting. It is used to balance and enhance flavours. It also is used as an artificial meat flavouring in vegetarian food products.
• in diet products, feed agents, medication and cosmetic products.

Gene technology

Classically, cysteine is won from proteins that are rich in cystine, such as are found in human hair or in feathers or pig bristles. The protein components are split into individual amino acids by being heated with hydrochloric acid. The cystine that hereby is isolated then is electrochemically reduced to cysteine.

• For a long time, the bio-technological production of cysteine was considered to be expensive and difficult. Since then, a German company (Wacker Chemie) has been successful in applying biotechnical processes to E. coli (Escherichia coli) bacteria for a profitable fermentative production of cysteine. The E. coli bacteria use glucose (sugar) and some mineral salts to produce the desired cysteine in large quantities and convey the amino acid into the nutrient solution. The process has been applied since 2001.
• The yield of such bio-technical production of cysteine is approximately 30 per cent higher than in the classical procedure. Additionally, the quantity of hydrochloric acid necessary for the bio-technical method is only four percent of the quantity that otherwise has been required.

Labelling: Additives that have been produced with the aid of genetically modified micro-organisms in closed systems need not be labelled as such, provided that the additive in question has been purified and contains no micro-organisms.

If the micro-organisms in question have received nutrient solution that has been derived from genetically modified plants, the additive remains without labelling as such.