L-Cysteine Works on Wheat Starch

SHIRAZ, IranL-cysteine is an amino acid reducing agent often used as gluten-relaxing dough conditioner in bakery production. But a recent study indicates it might also affect the wheats starch molecules.

Researchers at Shiraz University in Iran examined the effects of L-cysteine as a food additive on wheat starch characteristics before and after gelatinization. L-cysteine is traditionally used as a reducing agent to chemically break the disulfide bonds in gluten, which is similar to the mechanical action of dough mixing. This can reduce mix time and improve extensibility. Commercial bakeries add it to bread and other yeast and chemically leavened applications to increase production throughput and adjust for flour variation, as well as aid dough extensibility. The latter will decrease dough elasticity that can cause products to shrink or curl after they are formed.

In the experiment, L-cysteine was added to 30% slurry of wheat starch in water). One set of samples was mixed at 40 °C for 45 minutes and the other set was gelatinized at 100 °C for 45 minute. While the low-temperature samples did not essentially change, the higher gelatinization temperature reduced intrinsic, peak and final viscosities of the samples. Researchers theorized these changes might indicate degradation of starch molecules in the presence of L-cysteine, particularly after gelatinization.