RESUMO
The complexation between lysozyme/carrageenan and ovalbumin/carrageenan was studied in situ using acidification. The complexes were analyzed in solutions with different NaCl concentrations and different protein/polysaccharide ratios. As the protein/polysaccharide ratio increased from 1:1 to 10:1, critical structure forming events (i.e., those associated with soluble, insoluble and large insoluble complexes) shifted to higher pH values for ovalbumin/carrageenan followed by decrease of G' values at ratios of 5:1 and 10:1. The increase in the ratio of lysozyme/carrageenan complexes suppressed the critical pH transition points that led to the formation of large insoluble complexes from pH 12.0 until 1.0, and the values of G' increased simultaneously, reaching the highest value at a ratio of 10:1. Addition of salt to the ovalbumin/carrageenan and lysozyme/carrageenan mixtures suppressed the electrostatic interaction between proteins and carrageenan at lower pH values and the critical pH transitions points, whereas at a ratio of 3:1 with a 0.01â¯M concentration, the coacervate yield of the complex reached 79.6%⯱â¯0.6 and 93.7%⯱â¯4.8 for the ovalbumin and lysozyme complexes, respectively. The rheological data associated with microscopy images show that interpolymer complexes with heterogeneous structures were formed for both complexes, and we suggest that complexes have a great potential to improve or extend the texture, mechanical stability, consistency, and taste of food products.
Assuntos
Carragenina/química , Carragenina/metabolismo , Proteínas do Ovo/química , Proteínas do Ovo/metabolismo , Reologia , Relação Dose-Resposta a Droga , Concentração de Íons de Hidrogênio , Concentração Osmolar , Ovalbumina/metabolismo , Pectinas/metabolismo , Ligação Proteica/efeitos dos fármacos , Cloreto de Sódio/farmacologia , Solubilidade , TermodinâmicaRESUMO
The complexation between lysozyme and pectin was studied by acidification using zeta potential, turbidity measurements and calorimetry titration. The complexes were analyzed in various NaCl concentrations with different ratios. At ratio 1:1 with 0.01M NaCl, is worth mentioning that the insoluble complexes were formed between pH 2.0 and 7.0, which represents a great range to apply this complex to different food matrices. When the ratio was increased from 1:1 to 3:1, the pH range between the pHφ1 and pHφ2 increased even more. When the NaCl concentration was increased from 0.01M to 0.2M, a progressive reduction of turbidity was observed. At 0.4M NaCl, there was total suppression of complex formation at ratio ≤ 3:1. The process of complex coacervate formation occurred in two different steps, presenting favorable enthalpic as well as entropic contributions. The positive entropy change is a strong indication that water molecules have been released from the complex surface, however the positive sign of TΔS suggests that hydrophobic interactions were involved in the interaction between lysozyme and pectin. Microscopy images of the samples revealed that the complexes presented a spheroid-like appearance which may contribute to possible future applications.
Assuntos
Biopolímeros/química , Complexos Multiproteicos/química , Muramidase/química , Pectinas/química , Calorimetria , Entropia , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Cloreto de Sódio/química , TermodinâmicaRESUMO
In this study, interactions between polypeptide-leucine (0.2% w/w) and gum arabic (0.03, 0.06, 0.09, 0.12, and 0.15% w/w) were examined at concentrations of NaCl (0, 0.01, 0.25, 0.3, 0.5mol/l) and at different pH values (from 1.0 to 12.0). Formation of insoluble complex coacervates was highest at pH 4.0. At pH 2.0, which is the pKa of the gum Arabic, the dissociation of precipitate occurred. The pHØ2 positively shifted with the addition of higher concentrations of salt. Samples containing 0.2% PL and 0.03% GA and no salt had higher turbidity and increased formation of precipitates showing greater turbidity and particle sizes. The Fourier transform infrared spectroscopy confirms the complex coacervate formation of leucine and gum arabic, and rheological measurements suggest the elastic behavior of 0.2% PL and 0.03% GA complex. Overall, the study suggests that complex coacervates of PLs could be one feasible ways of incorporating amino acids in food products.
Assuntos
Goma Arábica/química , Leucina , Peptídeos/química , Concentração de Íons de Hidrogênio , Tamanho da Partícula , Reologia , Cloreto de Sódio/química , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
This study aimed at the characterization of blends of Sacha Inchi oil (SIO) with different ratios of SO (soybean oil) and CO (corn oil) by nuclear magnetic resonance ((1)H NMR), compared with the data obtained by gas chromatography with a flame ionization detector (GC-FID). The (1)H NMR and GC-FID data from different ratios of SIO were adjusted by a second order polynomial equation. The two techniques were highly correlated (R(2) values ranged from 0.995 to 0.999), revealing that (1)H NMR is an efficient methodology for the quantification of omega-3 fatty acids in oils rich in omega-6 fatty acids or vice versa such as SO and CO and, on the other hand, can be used to quantify ω-6 in oils rich in ω-3, such as SIO.