VISCOELASTICAL BEHAVIOUR OF SOME FOOD MATERIALS FROM THE SPANISH MARKET

Abstract

The yogurt presents a weak viscoelastical component due to the presence of the casein in its structure. These casein gels can be clearly distinguished from polymer gels that are formed by long macromolecules with a considerable conformational flexibility between crosslinks. On the macroscopic scale, particle gels are more brittle than polymer gels, and they tend to have a shorter linear elastic region and smaller fracture strain. the measurements of the viscoelastic parameters of weak gels must be done at very small deformations and the stress and the strain involved in the measurements may frequently be below the limits of accuracy of conventional rheological instruments. The purpose of this work is to observe the viscoelastical behavior of some yogurts from the Spanish market. For this study where picked two types of yogurt, simple yogurt and yogurt with fruit, respectively; four samples for each type, each one with different concentration of soluble content, fat content, protein and sugar content. The PCA realised obtained an explanation of the 2 components of 100%, and it was observed that yogurts are divided in two different groups, influenced by the physical chemical composition. The analysis of variance (ANOVA) conducted revealed that considering that a higher value of F-ratio means a more noticeable effect of the factor (type of yogurt) in a variable, G’ was the parameters more distinguished by the type of yogurt.