Characterization and Modeling of the Viscoelastic Behavior of Hydrocolloid-Based Films Using Classical and Fractional Rheological Models

Hydrocolloid-based films are a good alternative in the development of biodegradable films due to their properties, such as non-toxicity, functionality, and biodegradability, among others. In this work, films based on hydrocolloids (gellan gum, carrageenan, and guar gum) were formulated, evaluating their dynamic rheological behavior and creep and recovery. Maxwell's classical and fractional rheological models were implemented to describe its viscoelastic behavior, using the Vortex Search Algorithm for the estimation of the parameters. The hydrocolloid-based films showed a viscoelastic behavior, where the behavior of the storage modulus (G') and loss modulus (G'') indicated a greater elastic behavior (G' > G''). The Maxwell fractional model with two spring-pots showed an optimal fit of the experimental data of storage modulus (G') and loss modulus (G'') and a creep compliance (J) (Fmin < 0.1 and R2 > 0.98). This shows that fractional models are an excellent alternative for describing the dynamic rheological behavior and creep recovery of films. These results show the importance of estimating parameters that allow for the dynamic rheological and creep behaviors of hydrocolloid-based films for applications in the design of active films because they allow us to understand their behavior from a rheological point of view, which can contribute to the design and improvement of products such as food coatings, food packaging, or other applications containing biopolymers.

Dynamic Rheological Behavior of Chitosan/collagen Mixtures

Chitosan and collagen are naturally-derived materials with multiple applications, but their mixtures present phase separation phenomena. This shortcoming in relation to the mixture processing and, obviously, the applications can be overcome by choosing the appropriate composition. Rheological methods have been used to study collagen - chitosan mixtures to highlight their compatibility conditions in solution. Through the use of oscillatory rheometry, the viscoelastic behavior of collagen-chitosan mixtures in 0.5M acetic acid solution was analysed. The storage modulus (G`) was used to describe the elasticity of the material, while the loss modulus (G`) provided information on the viscous behavior of the mixtures.

Caesalpinia pulcherrima seed galactomannan on rheological properties of dairy desserts

ABSTRACT: Dairy desserts containing Caesalpinia pulcherrima seed galactomannan were evaluated to determine their static and dynamic rheological behaviors. Variations in consistency index (k), flow behavior (n), yield stress and thixotropy of the desserts indicated that the galactomannan caused an increase in the shear stress and apparent viscosity of the system. All samples exhibited shear-thinning behavior with flow behavior index values (n) between 0.06 and 0.37. Dynamic rheological behavior was evaluated for MD (high solid levels) and MD/2 (half the amount of solids) groups, and both G’ and G’’ moduli were depended on the frequency. The MD and MD/2 groups showed variations in the elastic modulus (G’) throughout the temperature range (mainly at 50 °C), showing greater sensitivity at high temperatures. C. pulcherrima galactomannan was able to promote synergism with starch, milk protein and sucrose and to improve the development of stronger and more resistant gels.