Complex coacervates obtained from peptide leucine and gum arabic: Formation and characterization

• Published in: Food chemistry 2016-03, Vol.194, p.680-686
• Main Authors: Gulão, Eliana da S., de Souza, Clitor J.F., Andrade, Cristina T., Garcia-Rojas, Edwin E.
• Format: Article
• Language: English
• Subjects: Bioactives; Biopolymers; Complex coacervation; Gum Arabic - chemistry; Hydrogen-Ion Concentration; Leucine; Particle Size; Peptides - chemistry; Polypeptide; Rheology; Sodium Chloride - chemistry; Spectroscopy, Fourier Transform Infrared; Whey proteins
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2015.08.062

•Polymers interactions occurred from the pH of the polypeptide isoelectric point.•Electrostatic interaction decreases at pH equal to the pKa of the gum Arabic.•The addition of NaCl decrease the complexation.•New structures were observed by using the FTIR and XRD analysis.•Through rheological analyses complex coacervates showed an elastic behavior. 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.