Formação de complexos coacervados a partir das proteínas da clara de ovo e polissacarídeos

Abstract

Proteins and polysaccharides are the most frequently used hydrocolloids in the food industry, and their interaction can provide products such as complexes coacervates. Ovalbumin-pectin coacervate complexes was analyzed in various NaCl concentrations with different protein:polysaccharide ratios by measuring zeta (ζ)-potentials, and by X-ray diffraction. Changes in protein concentrations led to shifts in the region of insoluble complex formation (at the isoelectric point). When NaCl concentrations increased from 0.1 to 0.4 M, complex dissociation were suppressed. X-ray diffraction of the ovalbumin-pectin coacervate complex showed a partially defined crystalline region from 27-20° suggesting that the structure of the complex is more organized than the individual amorphous polymers. The complexation between lysozyme (Lyso) and citrus pectin (Pec) were studied in situ by acidification (12.0-1.0) using zeta potential and turbidity measurements. The complexes were analyzed in different NaCl concentrations with different protein:polysaccharide ratios. In the ratio 1:1 with 0.01 mol/L of NaCl the region of the formation of insoluble complex corresponded a pH range 7.0 to 2.0 which represent a wide range to apply this complex on different matrix food. When NaCl concentration was increased from 0.01 mol/L to 0.2 mol/L was possible to see a progressive reduction of turbidity and the pH range of complex formation achieving in a total suppression of complex in 0.4 mol/L. The microscopy images of samples revealed that complexes presented spheroid like appearance with the heterogeneous structure containing a single core polymeric phase. The Lyso/Pectin complex particles described here may represents a great potential in various commercial applications in the biotechnological The complexation between lysozyme/κ-carrageenan and ovalbumin/κ-carrageenan was studied in situ by acidification (12.0-1.0) using zeta potential, turbidity and rheological measurements. The complexes were analyzed in different NaCl concentrations with different protein/polysaccharide ratios. As the protein:polysaccharide ratio increased from 1:1 to 10:1, critical pHs shifted to higher pHs with ovalbumin/κ-carrageenan complexes followed by a decrease of G’ values of the ratios 5:1 and 10:1. The increase of ratio with lysozyme/κ-carrageenan complexes suppressed the critical pH transitions points forming large insoluble complexes from pH 12.0 to 1.0 and the values of G’ increased simultaneously reaching the higher value of the ratio 10:1. Addition of salt to the ovalbumin/κ-carrageenan and lysozyme/κ-carrageenan mixtures suppressed the electrostatic interaction between proteins and κ-carrageenan. The rheological data associated with microscopy images showed that intrapolymer complexes with heterogeneous structure were formed for both complex, and we suggest that complexes represent a great potential to improving texture, mechanical stability, consistency, and taste of food products. The complexation between lysozyme (Lyso)/xanthan gum (XG) and ovalbumin (Ova)/xanthan gum was studied in situ by acidification (12.0-1.0) using zeta potential, turbidity, Fourier transform infrared spectroscopy (FTIR), and rheological measurements. The complexes were analyzed in different NaCl concentrations with different protein/polysaccharide ratios. The increase of the ratio from 2:1 to 10:1 for Lyso/XG complexes suppressed the pHφ forming insoluble at pH 12.0, however, the values of G’ decreased at ratio 5:1 and 10:1 indicating that excess of protein impact on compacted the network structures. Addition of salt in the Ova/XG and Lyso/XG mixtures suppressed the electrostatic interaction between proteins and XG shifting to lowering pHs the critical pH transitions points. The rheological data associated with microscopy images showed that interconnected gel-like network structure with heterogeneous structure were formed for both complex, and it is suggested that complexes represent a great potential to improve sensorial properties of food products. Formation of Lysozyme-Xanthan Gum (Lyso-XG) gels were studied with the objective to identify the role of individual biopolymer as well as the influence of their mixing ratio on gelation mechanism, texture properties, pores, and syneresis. The excess of protein affected the compaction of gel, which resulted in gels with dense clusters, with poorer water-bolding capacity. The gel strength mainly depended on the XG content, hence, at the ratio 1:2 hardness and held-water increased and final G' was almost five times stronger than ratio 1:1. Lyso-XG gels produced without heat treatment and with low water content presented a great potential for application in the food and pharmaceutical industry. Finally, the influence of protein (lysozyme and β-lactoglobulin) on hydrogels formation with xanthan gum was studied as a function of three different solid total concentrations. In general, the critical strain enlarged as far as the solid total of the system was increased, and gels became more stronger and rigid. Comparing the value of G' and G'' between gels produced with lysozyme, and β-Lactoglobulin, it was noted that Lyso-XG gels were stronger than BLG-XG. This experimental study elucidated fundamental aspects about texture formation of hydrogels and it is also suggested that results can be used by biomedical, pharmaceutical, and food industries to develop new functional semi-solid products with high water and low protein content.