Rheological properties, microstructure and sensory perception of high-amylose starch-pectin mixed gels

Different types of textures were generated by mixing amylose-rich HYLON VU maize starch, LM pectin with different Ca contents, with or without saccharose and maltitol. Before mixing, HYLON VU was heated to 150C, which allowed the dispersion of starch amylose and amylopectin. Pectin started to form a gel below 50C and HYLON VII at 20C. The magnitude of G' and the gelling rate were higher in mixed gels than in the corresponding single gels, at higher calcium contents, and in the presence of saccharose. A dramatic loss of G' was observed during the reheating of the gels, within the temperature range of 25-90C for pectin and 55-90C for HYLON VII. In mixed and saccharose-containing gels, pectin and starch did not lose gel structure completely. The microstructure of single gels was homogenous, whereas starch aggregates were observed in mixed gels. The sensory profile of single HYLON VII gel differed significantly from other gels; it was smooth, less firm, soft and melted easily in the mouth. The addition of LM pectin to the HYLON VII made the gel less smooth and harder, and structure changed less during reheating. The mixed gel with the lowest Ca content was very smooth, elastic and firm and differed considerably in sensory profile from other mixed gels. The correlation of maximum force of gels in compression with perceived hardness was r = 0.89 and that of G' at 37C with smoothness was r = -0.77. The smoothness of the gels was related to the absence of aggregated starch particles.