L-cystein is used to improve flours, which contain strong glutenic net, in order to reduce fermentation and kneading period, to fit some rheological properties and to obtain special dough elastic properties.
Flours who need improving with L-cystein, or other reducing agents, generate low volume products, small porosity and powerless flavor.
The action of L-cystein in dough, starts with reducing intramolecular disulfide –S-S- bonds, preventing them to participate at disulfide-sulhidril interaction reactions. Accordingly, glutenic net shapes faster, but it contains a smallest number of intramolecular bonds.
L-cystein and its derivatives are used in 10-90 ppm dosages. There are known a few theories about the action of L-cystein in dough. One of those considers that L-cystein, which contains a -S-S- bond, opens up disulfide bridges from glutenic proteins structure. Another theory, considers that L-cystein attacks disulfide bonds, by sulfidic radicals, which were born by physical breaking, during the kneading. Reaction is over when one of the two radicals, formed as a result of physical breaking of -S-S- glutenic bonds, accepts H+ coming from L-cystein molecule and the other radical binds to L-cystein residue, according to the following mechanism:
In this case, just a half of disrupted -S-S- glutenic bonds can be restored. According to Tsen (1979), L-cystein acts exclusive during kneading, but not during fermentation .
L-cystein is used for seasoning some dough, prepared from strong wheat flours, which are characterized by resistant glutenic net, slightly extensible, with the purpose of obtaining special rheological properties. The experiment consisted in the comparative evaluation of technological qualities of several control flours and the same flours improved by the addition of a L-cystein conditioner. The technological qualities investigated, had been represented by some rheological properties of dough (farinograms, alveograms), such as: development, hydration capacity (CH), stability, dough’s deformation energy (W), extensibility L, resistance P, P/L index, extensibility index G and elasticity index Ie. Finale, we realized a baking test, to investigate the influence of L-cystein conditioner upon the loaf qualities (volume, porosity, elasticity).
Observing the statistical evaluations of laboratory results, we may ascertain that the most sensitive parameter to L-cystein action, were: extensibility L, extensibility index G and P/L index. Farinographic parameters, such as development and stability, registered also important modifications, but not so ample as alveographic parameters. It had been also marked out the effects of L-cystein conditioner, upon some correlation between quality parameters in improved flours, comparative with control flours and the positive effects on the loaf qualities, like: volume, porosity and elasticity