Optimizing complex formation of Persian gum-Whey protein isolate

Persian gum is an anionic polysaccharide, exudes from mountain almond tree. Unfortunately, there is no information about its interaction with unfolded proteins. The objectives of the current study are investigation of heating time on the properties of WPI and the complexes thereof. In this regard, first the effect of thermal processing (at 80°C, for 0-35 min) on the turbidity of whey protein isolate was surveyed at pH 4.0. The electrostatic interaction between treated WPI and Persian gum was also surveyed as a function of heating time and mixing ratios (2:1, 1:1, 1:2, 1:5, 1:10 and 1:20). Results indicated the significant increasing in the turbidity of treated WPI solutions (mainly after 25 min) with a high inconsistency leading to the precipitation due to the protein-protein interactions at low pH and formation of large aggregates. Addition of Persian gum (PG) caused the formation of WPI-PG complexes and meaningful increasing in the stability of the mixture solutions. Furthermore, the rheological measurements (0-100 S-1) showed that the mixture solution has pseudoplastic behavior with a large hysteresis loop and higher viscosity rather than the blank solutions, indicating the formation of proteinpolysaccharide complexes. By calculation of protein and polysaccharide in the supernatant and precipitation phases, the most biopolymer concentration in the precipitation phase was demonstrated for the 35-min-treated WPI. On the other hand, the amount of polysaccharide was increased in the precipitation as WPI:PG mixing ratio decreased.