Extracts with Nutritional Potential and Their Influence on the Rheological Properties of Dough and Quality Parameters of Bread

Abstract

Formulating basic food to improve its nutritional profile is one potential method for food innovation. One option in formulating basic food such as bread is to supplement flours with specified amounts of non-bakery raw materials with high nutritional benefits. In the research presented here, we studied the influence of the addition of curcumin and quercetin extracts in amounts of 2.5% and 5% to wheat flour (2.5:97.5; 5:95). The analysis of the rheological properties of dough was carried out using a Mixolab 2. A Rheofermentometer F4 was used to assess the dough's fermentation, and a Volscan was used to evaluate the baking trials. The effect of the extracts on the rheological properties of dough was measured and found to be statistically significant, with curcumin shortening both dough development time and dough stability. Doughs made with greater quantities of extract had a greater tendency to early starch retrogradation, which negatively affects the shelf life of the end products. The addition of extracts did not significantly affect either the ability to form gas during fermentation or its retention, which is important because this gas is prerequisite to forming a final product with the required volume and porosity of crumb. Less favourable results were found on sensory evaluation, wherein the trial bread was significantly worse than the control wheat bread. The panel's decision-making might have been influenced by the atypical colour of the bread made with additives, and in case of a trial bread made with quercetin, by a bitter taste. From the technological point of view, the results confirmed that the composite flours prepared with the addition of extracts of curcumin and quercetin in amounts of 2.5% and 5% can be processed according to standard procedures. The final product will be bread with improved nutritional profile and specific sensory properties, specifically an unconventional and attractive colour.

Keywords: Mixolab; Rheofermentometer; baking test; curcumin; dough rheology; quercetin; sensory evaluation.

Figure 1

Flow diagram for bread processing.

Figure 2

Water absorption of the control flour (100%) and composite flours with extracts. * values are significantly different (p < 0.05) compared to the control. WF—wheat flour/control flour; C_2.5—composite flour with 2.5% curcumin extract; C_5—composite flour with 5% curcumin extract; Q_2.5—composite flour with 2.5% quercetin extract; Q_5—composite flour with 5% quercetin extract.

Figure 3

Dough development time and dough stability of the control flour and composite flours with extracts. * values are significantly different (p < 0.05) compared to the control. WF—wheat flour/control flour; C_2.5—composite flour with 2.5% curcumin extract; C_5—composite flour with 5% curcumin extract; Q_2.5—composite flour with 2.5% quercetin extract; Q_5—composite flour with 5% quercetin extract.

Figure 4

(a,b) Mixolab S protocol/Farinographic curves of the control flour and composite flour with curcumin extracts. (a) Control—wheat flour, (b) Curcumin_2.5—composite flour with 2.5% curcumin extract.

Figure 5

Rheological behaviour curves (CH+ protocol, Mixolab). WF—wheat flour/control flour; C_2.5—composite flour with 2.5% curcumin extract; C_5—composite flour with 5% curcumin extract; Q_2.5—composite flour with 2.5% quercetin extract; Q_5—composite flour with 5% quercetin extract. C1—maximum torque during mixing; C2—weakening of the protein; C3—rate of starch gelatinization; C4—minimum torque during heating; C5—torque after cooling at 50 °C.

Figure 6

Mixolab—calculated parameters: alpha, beta, and gamma slopes. * values are significantly different (p < 0.05) compared to the control. WF—wheat flour/control flour; C_2.5—composite flour with 2.5% curcumin extract; C_5—composite flour with 5% curcumin extract; Q_2.5—composite flour with 2.5% quercetin extract; Q_5—composite flour with 5% quercetin extract.

Figure 7

Mixolab Profiler-generated complete characterization (protein network, starch, and enzyme activity) of control flour and flour with the addition of extracts according to fundamental criteria: water absorption index, mixing index, gluten+ index, viscosity index, amylase index and retrogradation index. WF—wheat flour/control flour; C_2.5—composite flour with 2.5% curcumin extract; C_5—composite flour with 5% curcumin extract; Q_2.5—composite flour with 2.5% quercetin extract; Q_5—composite flour with 5% quercetin extract.

Figure 8

Rheofermentometer—evaluation of dough behaviour during fermentation according to fundamental criteria: H’m—maximum height of the gas-release curve; total volume—total volume of gas produced in mL CO₂; retention volume—CO₂ volume in mL retained in the dough at the end of the test. WF—wheat flour/control flour (100%); C_2.5—composite flour with 2.5% curcumin extract; C_5—composite flour with 5% curcumin extract; Q_2.5—composite flour with 2.5% quercetin extract; Q_5—composite flour with 5% quercetin extract.

Figure 9

Rheofermentometer curve of control dough and dough with addition of 2.5% extract. Green—control/wheat dough; purple—2.5% curcumin; blue—2.5% quercetin.

Figure 10

Baking experiment—evaluation of the technological quality of trial breads by Voscan. * values are significantly different (p < 0.05) compared to the control. WF—control/wheat flour/control loaf (100%); C_2.5—composite flour with 2.5% curcumin extract; C_5—composite flour with 5% curcumin extract; Q_2.5—composite flour with 2.5% quercetin extract; Q_5—composite flour with 5% quercetin extract.

Figure 11

Baking experiment—photographs of trial breads. WF—wheat flour/control flour; C_2.5—composite flour with 2.5% curcumin extract; C_5—composite flour with 5% curcumin extract; Q_2.5—composite flour with 2.5% quercetin extract; Q_5—composite flour with 5% quercetin extract.

Figure 12

Baking experiment—graphic scans of trial breads by Volscan. WF—wheat flour/control flour; C_2.5—composite flour with 2.5% curcumin extract; C_5—composite flour with 5% curcumin extract; Q_2.5—composite flour with 2.5% quercetin extract; Q_5—composite flour with 5% quercetin extract.

Figure 13

Baking experiment—sensory evaluation of the trial breads by means of a 100-point system. * values are significantly different (p < 0.05) compared to the control. WF—wheat flour/control flour; C_5—composite flour with 5% curcumin extract; Q_2.5—composite flour with 2.5% quercetin extract.

Figure 14

Baking experiment—colour spectra of trial breads evaluated by E-eye. 2944–4076—colour shades. WF—wheat flour/control flour; C_2.5—composite flour with 2.5% curcumin extract; C_5—composite flour with 5% curcumin extract; Q_2.5—composite flour with 2.5% quercetin extract; Q_5—composite flour with 5% quercetin extract.