Proteases in milling and bakery

The using of proteasic conditioners is practiced for the strong flours, which form highly resistent and highly elastic glutenic nets, with small extensibility, respectively for the products obtained in short technological processes, in which the fermentation times are reduced or do not exist (sticks, rolls, biscuits, waffers). The proteases addition takes into consideration the reducing of kneading times and the doughs’ weakening, as a result of the peptidic bonds hydrolysis in gluten. As a result of the enzymatic reaction, extensibility and others several dough’s rheological properties, appears to be increased.

The most frequent proteases’ sources are Aspergillus oryzae, Bacillus subtillis, and a range of vegetal products (like papain and bromelin). All the same, malt is an important proteases’ source, but its strong amilolytic effect makes it less desirable. The proteases’ hydrolitic effect is strongly dependent on the preparation source, the best results upon the dough’s rheology being obtained for fungic and bacterian proteases. The vegetal proteases produce a profound protheoliysis of the gluten, reason for which they are used extremely seldom.

The correct dosage of the proteasic conditioner added to the dough, is very important for obtaining good quality products. The proteases’ excess gives sticky dough with difficult processing, a reduced capacity of gases’ retention and a strong coloured crust. An underdosage gives small volume products, with a weak symmetry and breakable core.

The most illustrative analysis methods, for the effects of protease addition upon the flour proteins’ behaviour, are represented by the farinographic method and respectively the alveographic method. The farinographic method investigates the flour quality, according to the main farinogram characteristics, which are: development time, stability, softening, tolerance value. The farinogram represents the dough’s evolution film in specific kneading conditions, after obtaining a standard consistency of 500 U.B. (Brabender units). The alveographic method analyses the stretching resistance of a dough sheet, under the air’s pressure. It swells like a bubble until it breaks. We register: the maximum stretching resistance of the dough (P), the extensibility (L), the total energy and the P/L ratio (synthetic indicator for quality).

The present paper’s aim allude to the rheological behaviour analysis of some wheat flours dough, treated with proteases, in comparison with dough obtained from flours which have not been treated with enzymatic conditioners. We followed in the same time the identification of the statistic legislation to express the interdependency between the flours’ quality parameters and the protease quantity used for the improvement, in order to identify a mathematical method to simplify the dosage decision and to reduce the chances of mistake induction at this level, in the technological process.

 The experiment consisted in the comparative evaluation of technological qualities of several control flours and the same flours improved by the addition of an enzymatic conditioner with proteasic activity (26 samples). We explored some physical-chemical parameters as: moisture, protein, wet gluten, the gluten deformation index and the hydration capacity. Secondly, we explored the rheological characteristics, respectively the proper farinograms and alveograms.

Observing the statistical evaluations of laboratory results, we may ascertain that the most sensitive parameters for the proteasic action, were: gluten deformation index, stability, energy W, resistance P and P/L index. Least sensitive parameter at the protease treatment was hydration capacity.

Gluten deformation index in improved flours, can be strictly controlled per the protease addition, by the regression equation; dough’s deformation energy (W), resistance P and P/L ratio, in improved flours, can also be anticipated starting from the initial value of these parameters in control flours, relied on the regression equations, which depends on enzymatic conditioner quantity. The farinographic stability parameter in improved flours, was not significantly influenced by the starting value of the stability in the control flours, but correlated negatively distinctly significant with the enzymatic conditioner quantity.