Rheology of heterogeneous food systems on the basis of biopolymers

Abstract

Background.  Problem of transformation of complex food systems is incompletely solved. In the framework of this problem, the incompletely solved problem of three-dimensional structure of proteids, including collagen, takes place. In this regard, the authors propose solutions of this problem basing on the study of structural rheological properties of polydisperse heterogeneous systems on the basis of natural intentionally modified biopolymers, incl. their microstructures. The rotational viscometry and analysis of images obtained with the scanning electron microscopy have been used as test methods. As a result, dependencies of the dynamic viscosity from the speed rate of the shear deformation have been obtained. They have shown relatively regular changes of the viscosity indicators. Data from the electronic microscopy let us to diagnose the structure of raw material and specially prepared semi-finished product, dominated by biopolymers, for further processing in industries.

Purpose. Taking into account the problem urgency, introduced in the first part of the article, we have stated the characteristic dependence between the dynamic viscosity of the typical polymer solution – alginate (semi-finished product for artificial caviar production) and shear deformation speed rate.

Materials and methods. The directions of solving the issue of microstructure and properties of biopolymers from different groups are actualized. In particular, biopolymers of alginate type and proteins from the collagen group have been investigated.

The peculiarities of the denaturation of native proteins cause the necessity of their further study (analysis of the initial architectonics of molecules, their changes under chemical and/or thermal influences) in the preparation of raw materials for the product manufacturing, feeds, etc. The general orientation of process organization is to avoid denaturation transformations.

However, treatment in media with the adjustable pH level is expected. The example is the treatment with electrolyte solutions (OH^-), which weakens the complex of cross-links, which causes some disturbance of the original histological structure of tissues, but does not lead to denaturation, preserving in general the molecular structure of the main structural molecular units (chains) of proteids.

Results. The first section of the rheogram, the “difficulty” of the system shear and then, a relatively uniform course of the graph, which may indicate that this solution is “stabilized” by structural agents based on natural biopolymers. The approximation reliability coefficient R2 = 0.98 demonstrates a high approximation of the trend line to the exponential model of the equation.

It is worth to mention the study by E.Yu. Agarkova et.al. which made it possible to reveal the exponential dependence between dynamic viscosity of polydisperse milk-based food systems depending on the mass fraction of psyllium in them. The obtained rheograms revealed nonlinear and non-additive dependences between viscosity and psyllium content in them.

Enhancing our own results, we have pointed out that the composition of the studied Collagen brand supplements also includes color-forming and flavor-forming additives. Comparative analysis of rheological data is hampered by the lack of publications in domestic sources. There is some information on mechanical parameters (e.g., the Young modulus, etc.) for protein hydrogels in foreign sources, F. Linglan. However, the elasticity modulus is used to characterize hydrogels.

It seems that these results are consistent with the studies of biopolymers by Hu Shiao et.al. [16], who revealed the special rheology of biopolymers with carbohydrate compartment. Thus, their thixotropic behavior was revealed.

Conclusion. The non-Newtonian flow character of biopolymer solutions can be characterized as visco-plastic, the properties of thixotropic medium were observed.

Based on the obtained results, the database on rational directions of processing of various biopolymers, which play, first of all, the role of structure formers, is being replenished. It is possible to combine these or those biopolymers in vitro with the purpose of further involvement in the production of food products and biologically active food additives.

The use of the combinatorics principles, more effective and functional food systems, will establish the compliance of the developed products with the principles of healthy nutrition. Especially it expands the possibilities of tissue repair from the group of supporting tissues, optimizes the functions of the gastrointestinal tract of humans and/or animals.

Thus, prospects for the food system development, creation of new feeds, materials for medical purposes, etc. are opened.

EDN: OLCPZI