Characterization of a novel complex coacervate based on whey protein isolate-tamarind seed mucilage

A complex coacervate was prepared with whey protein isolate (WPI) and tamarind seed mucilage (TSM) and was compared with a commonly used whey protein isolate (WPI)-gum Arabic (GA) complex coacervate. Protolityc titration, zeta-potentiometry and turbidimetry analyses were used to determine structural transitions during coacervate formation. Hydrocolloid blending ratio and pH effects on phase transitions were examined to finding the maximum strength interaction of the complex coacervates. The optimum WPI-TSM complex coacervate ratio and the pH value were 1: 0.3 and 3.68, respectively. In contrast, the WPI-GA complex coacervate reached the optimal interaction at ratio of 1.4:1 and pH = 3.46. The complex coacervates were spray-dried and analyzed to characterize structural, morphological and thermal properties. The results of FTIR showed that the formation of complexes was by means of electrostatic interactions and hydrogen bonds. The XRD analysis of WPI-TSM complex revealed higher crystallinity with respect to WPI-GA complex. The spray-dried complex coacervates exhibited clusters of amorphous aggregates, smooth and non-fractured particles. Thermal stability showed that coacervation enhanced protein stability as compared to WPI alone. Besides, WPI-TSM complex coacervate exhibited higher thermal stability than its WPI-GA counterpart. Therefore, WPI-TSM complex coacervate can be used as an economic and nutritionally valuable alternative for food additives. (C) 2017 Elsevier Ltd. All rights reserved.