Low gluten flour is needed to make pastries, cookies, etc. Reducing agents are usually used to weaken gluten, and in addition to reducing agents, protease is used to reduce the elasticity of dough.

Reducing agent

Reducing agent is a kind of chemical substance that can reduce the strength of dough, shorten the time of dough and make dough have good plasticity and extensibility. Its mechanism of action is mainly to react with the disulfide bond, so that the disulfide bond in the protein molecule is broken and transformed into the sulfur hydrogen bond, reducing the cross-linking degree of the protein, and the protein is changed from a large molecule to a small molecule, reducing the strength, elasticity and toughness of the dough.

Commonly used reducing agents are L-cysteine, sodium bisulfite, sorbic acid and so on.

L-cysteine

L-cysteine hydrochloride is mainly used in food processing for baking products, such as biscuits and bread improvement. It can activate the protease activity in the flour, can make the dough soft, enhance the fluidity, improve the plasticity of the dough.

L-cysteine hydrochloride can reduce the elasticity of dough, shorten the fermentation time in bread production, and improve the elongation of noodles in noodle production. L-cysteine contains free sulfhydryl group and can produce glutathione under certain conditions, which has a certain antioxidant effect.

Sodium bisulfite

Sodium metabisulfite and sodium bisulfite containing SO2 groups, the mechanism of action is: these reducing agents release the reducing effect of SO2 when mixing with the noodles, the disulfide bond in the gluten is opened and broken into sulfhydryl -SH, the gluten is weakened, the dough is easy to extend and expand, so as to shorten the mixing time and improve the plasticity of the dough. 

Because the amount of these sulfites will be too much residue, to bring odor to the food, so the amount should not be too much, generally not more than 0.06% of flour. 

Nowadays, most flour is treated with protease and cysteine as reducing agents.

Protease

The mechanism of protease to change the process properties of flour is to decompose gluten protein into amino acids and other substances, cut off the peptide chain of protein molecules, thereby reducing the strength of gluten and improving its plasticity. The effect of protease on protein is irreversible and cannot be overdone.

Protease has the function of cutting protein peptide bond, destroying gluten network structure, weakening the mechanical load resistance of dough, softening dough, improving the extensibility and decreasing the viscoelasticity.

Protease can be used in strong flour to reduce the elasticity of dough and increase its ductility. Moreover, the specific effect of protease is strong, and it can replace sodium metabisulfite in the production of cookies and desserts, avoiding the adverse effects of destroying vitamins due to the use of sodium metabisulfite.

Starch

Adding a small amount of starch to the flour can dilute the gluten concentration, reduce the elasticity, toughness and strength of the dough, improve plasticity, adjust the degree of gluten swelling, make the dough smooth, and make the product shape regular. The amount of starch is usually 5% to 10% of flour.

Cooked flour

According to the principle of protein thermal denaturation, the flour is steamed or baked to mature the flour, so that the gluten protein is denaturated and the function of water absorption and expansion is lost, and then added to the raw flour to reduce the strength of the dough.