Influence of damaged starch on the quality parameters of wheat dough and bread

Abstract

Introduction. A certain degree of damage to the starch granules is desirable but excessive level of starch damage can have deteriorating effect on the quality of the bakery products. Materials and methods. The wheat flour with lower (3.15%) and higher degree of starch damage (6.13%) were produced by repeat grinding (two passes) in a laboratory mill. The rheological measurements of dough samples were conducted using Farinograph and Extensograph, and gelatinisation and pasting properties-differential scanning calorimetry and Micro Visco-Amylo-Graph. Texture profile analysis of bread samples were performed using a texture analyser, and specific volume by laser topography method. Results and discussion. The dough mixing properties were generally better for the samples with a higher level of starch damage and the most significant improvement has been manifested in the increased water absorption, from 60.7% to 63.8%. Higher water absorption can be associated with the influence of starch damage but also with the effect of flour particle size because smaller particles have larger total surface area. The starch damage had no significant effect on most of the extensographic indicators, although a slight decrease in resistance and extensibility was observed. Samples with a higher degree of starch damage showed decreased gelatinisation power. The gelatinization enthalpy (ΔHg) decreased from 1.41 to 1.31 J/kg, and amylographic peak viscosity from 582.5 to 505.0 BU. This could be explained by the restricted swelling of damaged starch granules due to the loss of organised structure. There were no significant differences in the moisture content and water activity between samples with different damaged starch content. The starch damage had a significant impact on majority of the bread quality parameters but the hardness increase and specific volume were most pronounced. The hardness increased from (from 4.09 N to 5.25 N) and specific volume (from 4.04 cm3/g to 3.53 cm3/g) when flour with a higher degree of damaged starch was used. Conclusions. The level of starch damage had a significant effect on the dough rheological properties, starch gelatinisation and pasting properties, as well as on the bread quality parameters.