Light microscopy images of the control yogurt (C) (Fig. 2) showed a gray-colored protein network, stained with toluidine blue. Sample MP had denser areas than sample c (Fig. 2, first column) owing to the addi-tion of extra milk protein. In the WP sample, two protein networks could be distinguished: a gray-colored one described above and a faint blue-colored network that corresponds to the whey protein. In the added-starch samples (CS, MPS and WPS), violet-stained starch granules could be observed embedded in the protein networks (Fig. 2, third column).