Starch–fenugreek (Trigonella foenum-graecum L.) polysaccharide interactions in pure and soup systems

The effect of replacement of varying levels of a fenugreek polysaccharide (FP) product (0.1–0.9%) on 5% wt/wt corn starch cream soups and pure starch systems was investigated. Pasting, textural and viscoelastic characteristics along with granule size and sensory properties were determined. Significant changes were revealed with increasing FP replacement, with the effects being more pronounced on the soup formulations compared to the effects on pure starch/fenugreek systems. In soup formulations, peak viscosity, setback and final viscosity increased, while breakdown and pasting temperature decreased significantly. Accordingly, the apparent viscosity measured on the cooked soups and pure starch/fenugreek systems increased gradually at all fenugreek levels (≤0.9% wt/wt) and revealed a shear-thinning behaviour. While measuring the viscoelastic properties of the cooked soups, a greater impact of fenugreek level on the viscous portion compared to the elastic portion was detected. Elastic character specially improved above 0.15% wt/wt fenugreek in the soup formulations whereas no systematic effect was found in pure starch/fenugreek gels. Possible explanations based on the interactions between amylose and FP or segregation of components leading to an increase in the effective concentration of biopolymers are given. In soup formulations, the starch granule size decreased especially at ≥0.5% FP levels. In terms of creaminess, soups containing FP scored higher than in its absence. In terms of taste, the soups with no FP or with a high level of it (0.9% fenugreek) scored the lowest. Soup replaced with 0.5% fenugreek was evaluated to have the best taste and overall acceptability.