Influence of the microstructure on the sensory quality of whey protein gels

A full two-level factorial experimental design was used to study particulate whey protein gels. The processing conditions, pH, heating rate and the addition of salt were used as design factors. The results were evaluated by using a response surface model, and analysis of variance, M(ANOVA), was performed. The microstructure of particulate whey protein gels has been characterized previously, and the two-dimensional images from light microscopy and transmission electron microscopy were quantified by a stereological approach, while the more three-dimensional scanning electron micrographs were quantified by an expert panel of microscopists. In this study the texture of the same gels was analysed by a sensory panel Correlations were made between the microstructure and sensory descriptors, and the panellists were able to detect differences between very small particles <1 mu m(3) in volume. The sensory descriptors grainy appearance, gritty texture, creamy texture and tendency to fall apart had a logarithmic dependence on the microstructural parameters, particle size, and size of small and large pores. Multivariate techniques were used To create models to describe groups of the sensory descriptors by some of the microstructural parameters. A model with good correlation (r similar to 0.8-0.9) was found for grainy appearance, gritty texture, creamy texture and falling apart. They were all dependent on the star volume of particles and small and large pores. The soft and springy textures were influenced by combinations of microstructural parameters, where the formation of strands into strings of beads or in clusters and conglomerates seemed to play an important role. The sticky texture was negatively correlated to the proportion of threads within the pores.