Effect of disulphide bonds and sulphhydryl concentrations on properties of wheat flour.

Disulphide bonds and sulphhydryl concentrations were evaluated to determine the effects on rheological, thermodynamic, pasting, and dynamic rheological characteristics of mixed flours. Gluten samples, first treated with sodium sulphite of different concentrations, were added into flour at a 4% level, which had a significant impact on free sulphhydryl, disulphide bonds, and the ratio of the two indices. There was no relevance between the ratio and other parameters except for free sulphhydryl. The mixed flour doughs had reduced water absorption, dough development time, dough stability time as well as degree of weakening (P < 0.05). Disulphide bonds were associated negatively with the rate of starch gelatinisation (C3-C2), peak, and setback and these characteristics were correlated strongly with dough development time, dough stability time, and progressive protein weakening (C2-C1). The stability of starch gelatinisation and cooking stability of mixed ours did not remain significantly different. The larger the concentration of sodium sulphite, the higher the peak, breakdown, final viscosity, and setback values, but there were no significant differences between samples. For all samples, storage modulus and loss modulus increased with increasing scanning frequency. For mixed doughs, the trend lines of moduli decreased with increasing levels of reduction in added gluten. There was no substantial effect on thermal properties of flours. [ABSTRACT FROM AUTHOR]