## 3 Results and Discussion
### Flow Behaviour of the Instant Soups  
In Figure 3, the viscosities at 60 \({}^{\circ}\)C of the REF soup (at medium concentration) and the NG-O, PG-O, and INS containing soups (at low, medium, and high concentrations) are shown at different shear rates. The lowest shear rate (1 s\({}^{-1}\)) represented the serving condition of the soup, the shear rate of 48 s\({}^{-1}\) was an approximation of the shear rate during swallowing, and the rate of 250 s\({}^{-1}\) represented mixing [36; 37]. Figure 3 shows that the flour concentration largely affected the viscosity at the lowest shear rate (1 s\({}^{-1}\)), whereas the viscosity seemed to be concentration independent at the higher shear rates (in this concentration range). This indicates that different network structures were formed in the different soups but that the critical concentration to significantly influence the viscosity was only reached at the high concentration, as no significant differences were found between the low and middle concentrations [38]. However, this network was readily broken down at a shear rate of 48 s\({}^{-1}\), which represents swallowing, probably due to the alignment of particles with the flow direction [39]. Figure 2: Micrographs showing the microstructure of suspensions of potato starch (PS), non-gelatinised open cell chickpea flour (NG-O), pre-gelatinised open cell chickpea flour (PG-O), and commercial pre-gelatinised chickpea flour (INS) dispersed in cold (20 \({}^{\circ}\)C) and boiling (100 \({}^{\circ}\)C) water (Magnification 20\(\times\). Scale bar: 50 \(\upmu\)m). Considering the viscosity during serving, swallowing, and stirring conditions, all soups containing chickpea flour were comparable to the REF soup at both medium and low flour concentrations. Since the aim of this research was to obtain an acceptable soup, while additionally improving the nutritional quality, the medium concentration of chickpea flour was chosen for further analyses. In this way, a higher nutritional improvement was obtained compared to the low flour concentration. Considering the protein contents of the chickpea flours was around 18-22% (\(w\)/\(w\)) (as analysed by [PERSON] et al. (2021) [6] for NG-O and PG-O and as informed by the supplier for INS), the 1:1 replacement of PS with chicken flour results in a 3-4% (\(w\)/\(w\)) increase in high quality protein in the soup powder. Additionally, the replacement contributes to an increased vitamin and mineral content. In Figure 4, the viscosity curves at 60 \({}^{\circ}\)C of the soups with a medium concentration of PS or chickpea flour are given over the shear rate range 1-250 s\({}^{-1}\). Two phenomena are visible, namely shear-thinning behaviour at lower shear rates and shear-thickening behaviour at higher shear rates. This type of viscosity curve was previously described for starch-water suspensions [39; 40]. Figure 4: Viscosity curves at 60 \({}^{\circ}\)C of instant soups containing potato starch (REF) (\(\blacksquare\)) or non-gelatinised (NG-O) (\(\blacklozenge\)), pre-gelatinised (PG-O) (\(\bullet\)) or commercial pre-gelatinised (INS) (\(\blacktriangle\)) chickpea flour at medium concentration, showing viscosity (\(\eta\)) as function of shear rate (\(\dot{\psi}\)). Figure 3: Viscosities 60 \({}^{\circ}\)C of instant soups containing potato starch (REF) or non-gelatinised (NGO), pre-gelatinised (PGO) or commercially available pre-gelatinised (INS) chickpea flour at low, medium (med), and high concentrations (Table 1) at different shear rates. Viscosity values indicated with the same letter are not significantly different (\(\alpha\) = 0.05). The shear thinning behaviour of the soups seems to be the lowest for the REF soup and the highest for the INS soup. Shear thinning behaviour results from particle layering with the direction of flow, making them more easily slide past each other compared to when they are randomly distributed [39].