L-cystine (E921)

Purpose and Function

L-cystine (E921) is a naturally occurring amino acid used primarily as an improving agent in the food industry. It plays a key role in strengthening dough by forming disulfide bonds, which enhance the elasticity and texture of baked goods. L-cystine is particularly useful in the production of bread, pasta, and other wheat-based products, where it improves dough handling and final product quality.

Beyond its role in food, L-cystine is also used in dietary supplements and pharmaceuticals due to its antioxidant properties and its role in protein synthesis. It is often derived from natural sources or synthesized for commercial use.

Potential Risks and Side Effects

L-cystine (E921) is generally recognized as safe (GRAS) by regulatory bodies like the FDA and EFSA when used in approved amounts. However, excessive consumption may lead to imbalances in amino acid metabolism, particularly in individuals with pre-existing conditions such as cystinuria, a genetic disorder that affects cysteine and cystine processing.

There are no significant studies indicating severe adverse effects from L-cystine when consumed in moderation. However, as with many food additives, overconsumption should be avoided to prevent potential gastrointestinal discomfort or metabolic stress.