Subprojeto 19 – Structure evaluation of protein-polysaccharide interactions for development of new ingredients and materials for food industry
Participante: Rosiane Lopes da Cunha (DEA/FEA/Unicamp)
Our research group studies mainly protein-polysaccharide interactions and it is composed by a post-doc, 4 master and 3 PhD students. Such research is financed by two projects entitled “Micro and nano food emulsions: rheo-optical and stability study” (Fapesp) and “Manipulation of rheological and structural behavior of food systems by protein, polysaccharide and food fibers interactions” (CNPq). Protein-polysaccharide interactions are widely exploited by the food industry in order to develop new products with distinct textures, to encapsulate functional products with controlled release and to produce new ingredients, as emulsifiers or gelling agents. In particular, the two latter topics have been extensively studied in literature, especially because of the growing interest to use nanotechnology in food science and to obtain “healthy” food, such as the encapsulation of antioxidant agents to prevent cancer and degenerative diseases. Biopolymeric interactions can be segregative (resulting in phase separation) or associative (leading to coacervation), depending on several factors (environmental and process conditions and composition), which determine the structure/functionality of formed systems. Although there is a practical importance of manipulation and control of biopolymeric interactions, the most of published works has used indirect measurements to evaluate structure (water holding capacity and low deformation rheological properties) or invasive techniques, such as electronic microscopy. In this way, the evaluation of food microstructure using non-invasive techniques allows the identification of each component and their interactions during structure formation, as well as at equilibrium conditions, making possible the correlation between structure and macroscopic properties (stability and texture). Confocal microscopy is an excellent tool to the evaluation of systems with protein, since this macromolecule can be easily marked. Nevertheless, systems containing two polysaccharides with similar structure could be evaluated using Raman spectroscopy to map the distinct structures. Moreover, the combined use with other techniques, as multivariate curve resolution (MCR), allows the construction of phase diagrams when segregative interactions are predominant. Regarding emulsions, the microscopic techniques based on the transmission or reflection do not provide sufficient contrast for visualizing the different phases (water and oil) due to the similarity of their refractive indexes. Thus, emulsions containing water and oil could be evaluated through Raman spectroscopy and CARS microscopy, which are based on light dispersion. The Raman spectroscopy and confocal microscopy can also be used to evaluate emulsion stability during its consumption, for the production of low-fat emulsions, maintaining the same sensorial perception as traditional ones.