Surface morphology of soybean, pea, whey protein isolates, and their dried gels

Introduction. The hydrocolloids of plant and animal origin are widely used in food technologies, especially in the meat and dairy products manufacturing. The aim of this study was to investigate the surface morphology of some proteins isolates of plant origin and hydrated gels made from them. Materials and methods. The protein isolates of soybean, pea and whey as well as K-carrageenan, and guar gum were used in this study. We prepared gels of the isolates with low fats milk at the ratio 1:6 and 1:8. Structural changes of soybean, pea, and whey protein as well as their hydrates were observed by use of scanning electron microscope JSM-6700F. Results and discussion. The presence of coarse particles was observed in the samples of soybean and pea isolates, whereas sample of whey isolates had spherical shaped particles only. We found that, pea and soybean isolates did not differ significantly in their sample size, which was approximately 40 mu m. The low hydration level of the isolates at a ratio of 1:5 lead to smooth surface formation with the large number of holes. The remains of the large globules can be identified in the sample of hydrated pea isolate as the edges of dried spheres, which sizes are similar to those of initial isolates. Increased hydration level up to 1:8 resulted in the crosslinking between the proteins macromolecules and lead to carcass formation. Polysaccharides incorporation into the mixture of stabilizers resulted in the surface formation of gels which morphological features were similar to those of protein isolates of pea, soybean, and whey. However, this was further resulted in the gel structure formation with the minor crosslinking Conclusions. Increased amount of milk in the gels resulted in the development of 3D structure formation, as expected. Pea isolate was characterized by the great ability to the crosslinking between macromolecules of proteins.