Using fractal image analysis to characterize microstructure of low-fat stirred yoghurt manufactured with microparticulated whey protein

Differences in the microstructure of low fat yoghurt manufactured with microparticulated whey proteins used as fat replacer were investigated. Images were obtained by confocal laser scanning microscopy and studied using a technique for image analysis that combines an initial 2D-wavelet compression followed by fractal analysis and inspection of the fractal curves by principal components analysis (PCA). One commercial and three experimental microparticulated ingredients with different chemical characteristics were used in the yoghurt formulations and compared to both full and low fat yoghurts without fat replacer. The results showed that the amount of native and soluble whey proteins present in the microparticles had a positive influence on the structure of the formed gel. The created structure, dominated by dense aggregates and low amount of serum, had an increased degree of self similarity or fractality with yoghurts in which fat was present.

► Fractal analysis and PCA are objective tools to quantitate microstructural changes.
► Native and soluble protein in microparticles has positive effect on gel structure.
► This structure showed high degree of similarity with full fat yoghurts.
► The results show the importance of microparticle selection to optimize texture.