7. Hydrocolloids
7.1 Effect of hydrocolloid type on texture of pureed carrots: Rheological and sensory measures
Abstract
This research is an investigation of the effect of selected hydrocolloids on the texture of pureed foods. Modified starch, xanthan, carrageenan, carboxymethyl cellulose, pectin, gellan, and two proprietary hydrocolloids were added to pureed carrots and textural properties were examined. ThickenUp®, a commonly used modified corn starch thickener used when making pureed foods, was used as a reference. Rheological measurements, texture profile analysis (TPA), and sensory testing were employed to characterize the texture of the purees. It was hypothesized that hydrocolloids have no effect on texture and sensory properties of pureed carrots once the viscosity is matched at a shear rate of 50 s−1. The results indicated clear differences in the behaviour of hydrocolloids under small and large deformation measures. Carrageenan had a very stiff structure, which was susceptible to fragmentation, while CMC with a weak gel structure was easy to form a swallow-able bolus. It was observed that although pectin had a strong gel structure at rest, it had a high cohesiveness when subjected to large deformation. Trained panel sensory results indicated textural similarities amongst a starch-gum blend, xanthan and CMC. Viscosity at 10 s−1, yield point (rheology) and gumminess (TPA) correlated well with three sensory attributes amongst the five tested by the panel.