Complex coacervates obtained from lactoferrin and gum arabic: Formation and characterization |
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Affiliation: | 1. Programa de Pós-graduação em Ciência e Tecnologia de Alimentos (PPGCTA), Universidade Federal Rural de Rio de Janeiro (UFRRJ), Rodovia BR 465, Km 7, Seropédica, RJ 23890-000, Brazil;2. Laboratório de Engenharia e Tecnologia Agroindustrial (LETA), Universidade Federal Fluminense (UFF), Av. dos Trabalhadores, 420, Volta Redonda, RJ 27255-125, Brazil;3. Departamento de Tecnologia de Alimentos, Universidade Federal de Viçosa (UFV), 36571-000 Viçosa, MG, Brazil;1. College of Food Science and Engineering, Qingdao Agricultural University, Qingdao 266109, China;2. Institute of Agro-Food Science and Technology, Shandong Academy of Agricultural Sciences, Jinan 250100, China |
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Abstract: | Proteins and polysaccharides are the most frequently used hydrocolloids in the food industry, and their interaction can provide products such as complexes coacervates, which can be used as ingredients and biomaterials or in microencapsulation systems. In the present work, the interaction between lactoferrin (0.1, 0.2, 0.3, 0.5 and 1% w/w) and gum arabic (0.1% w/w) with various concentrations of NaCl (0, 0.01, 0.25, 0.3 and 0.5 mol/L) and at various pH values (from 1.0 to 12.0) was studied. The pH for the formation (higher turbidity) of the insoluble complex coacervates (pHØ1) varied according to the amount of NaCl used in the system (pH 3.5 to 5.3); these values are below the isoelectric point of lactoferrin (8.0), at which the protein is more positively charged, generating electrostatic binding. At a pH of approximately 2.0, this bond weakens, leading to the solubilization of precipitates, resulting in a sudden decrease in the turbidity (pHØ2). Samples containing a lower concentration of lactoferrin (0.1, 0.2 and 0.3% w/w) showed greater turbidity and consequently a higher formation of precipitates or aggregates. Even these samples, which contained a salt concentration of 0.3 mol/L, showed higher turbidity and displacement points of pHØ1 and pHØ2. The zeta potential and particle size values were used to study the influence of the pH, ionic strength and temperature on the interaction between the biopolymers. It was observed that the formation of macromolecules occurred between the isoelectric point of the protein (8.0) and the pKa of the polysaccharide (2.0), and a certain salt concentration (0.25 mol/L) led to larger particle sizes. It was observed that, at pH 7.0, a concentration of 0.1% gum arabic was able to stabilize the denaturation of the protein in solutions containing 0.1% lactoferrin, resulting in a constant particle size at all temperatures studied. |
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