Influence of sugars on the formation of structural and mechanical characteristics of of agar polysaccharides' gels
Ukrainian Journal of Food Science
Introduction. The current scientific task is to establish differences in structural and mechanical characteristics of agar and k-carrageenan gels with different types of sugars (saccharose, glucose, fructose, lactulose). Materials and methods. Structural and mechanical characteristics of agar polysaccharides' gels (agar, k-carrageenan) are the instantaneous springy modulus, elastic modulus, springy, elastic and plastic deformation. They were investigated by method of tangential displacement of
... he plate. There were used model systems of gels on agar and k-carrageenan with saccharose, glucose, fructose and lactulose. Results and discussion. Gels of agar polysaccharides can withstand different maximum loads depending on the type of sugar. The instantaneous springy modulus had the highest values in gels with saccharose, both on agar and on k-carrageenan, and the values of the modulus of elasticity were higher for gels with monosaccharides. In our opinion, the differences are explained by the difference in the spatial structure and molecular weight of sugars, which imprints on the ability to bind water, that is, hydration ability. Values of total deformation depend on the type of gel: for agar and k-carrageenan gels on different sugars the dependences are different. The greatest value of the total deformation of agar gel has a sample with saccharose -42.38 c.u. For k-carrageenan gels, the greatest value is the total deformation with monosaccharides. In this case, both agar and k-carrageenan samples with saccharose have higher values of the springy deformation index than the total number of elastic and plastic deformations. However, independently of the polysaccharide, the use of glucose and fructose gives elasticity and plasticity to gel. Adding lactulose to agar polysaccharides' systems leads to a strengthening of the structure of the formed gel, as evidenced by higher values of the force of maximum load for each system. Conclusions. The individual influence of saccharose, glucose, fructose, lactulose on the structural and mechanical characteristics of gels of agar and k-carrageenan has been established. Disaccharides in general cause greater springy modulus, while monosaccharides cause greater modulus of elasticity of systems and an increase in the total proportion of elastic and plastic deformation.