Complex Coacervation of Milk Proteins with Sodium Alginate

• DOI: 10.1021/acs.jafc.7b03915
• Publication Date: 2018-02-28T21:56:10Z
• Authors: Elham Ghorbani Gorji; Abdul Waheed; Roland Ludwig; José Luis Toca-He...; Gerhard Schleining; Sara Ghorbani Gorji
• Keywords: Isothermal Titration Calorimetry; Alginates; Viscosity; Hexuronic Acids; Milk proteins; Serum Albumin, Bovine; Lactoglobulins; 04 agricultural and veterinary sciences; Calorimetry; Hydrogen-Ion Concentration; 1600 Chemistry; 540; Milk Proteins; 1100 Agricultural and Biological Sciences; Glucuronic Acid; Complex coacervation; Animals; Cattle; Particle Size; Sodium alginate; 0405 other agricultural sciences

Beta-lactoglobulin (BLG) and bovine serum albumin (BSA) coacervate formation with sodium alginate (ALG) was investigated by turbidimetric analysis, zeta potential, particle size, viscosity, transmission electron microscopy (TEM) and isothermal titration calorimetric (ITC) measurements as a function of pH (1.0-7.0) and protein/alginate mixing ratio (1:1, 1.5:1, 2:1, 1:0, and 0:1 wt.). Critical pH values of phase transitions for BSA-ALG complexes (pHC, pHφ1, and pHφφ2) representing the formation of soluble and insoluble complexes of a protein-ALG mixture (2:1) at pH 4.8, 4.2, and 1.8, respectively. In the case of BLG-ALG, critical pH values (pHC, pHφ1, and pHφ2) were found to be 4.8, 4.2, and 1.6, respectively. The pHopt values, expressed by the highest optical density, were pH 2.8 for BSA-ALG and 2.4 for BLG-ALG. TEM and zeta-potential results showed that maximum coacervate formation occurred at pH 4.2 for both protein-polysaccharide solutions. The interaction between BLG-ALG and BSA-ALG was spontaneously exothermic at pH 4.2 according to ITC measurements. The findings of this study provide insights to a thorough understanding about the nature of interactions between milk proteins and ALG and formulate new applications for food, pharmaceutical, nutraceutical, and cosmetics applications.