Surface tension and interfacial rheological behavior of the mixtures buffalo whey protein concentrate - vitamin E

BUSTOS, LEANDRO FABIÁN; VASILE, FRANCO EMANUEL; VICTOR MANUEL PIZONES RUIZ-HENESTROSA; CECILIO CARRERA SÁNCHEZ; PÉREZ, OSCAR EDGARDO

Conferencia; Annual European Rheology Conference - AERC 2022; 2022

Buffalo whey proteins were recently reported as a promising carrier agent of vitamins by complexation. However, the impact of involved molecular interactions on surface properties of proteins were not yet assessed. By this reason, the objective of this work was to explore the impact of vitamin E on surface activity and interfacial dilatational rheology of a whey protein concentrate (BWPC). With this purpose, BWPC was dispersed at 1.6 ? 1.3 x10-5 % w/v in phosphate buffer pH 7 and opportunely mixed with 4.7 x10-3 % dl-α-tocopheryl acetate (α-TOC). BWPC dispersions without and with α-TOC were equilibrated at 4 °C for 24 h and the equilibrium superficial pressure (π) was registered through Wilhelmy plate method. Additionally, the rheological dilatational behavior (10 % deformation amplitude and 0,1 Hz of angular frequency) of BWPC solutions with 2.6 x10-2 % of proteins were assessed over 3 h. Plate tensiometry showed that π of BWPC solutions increased from 1.18 to 28.52 mN/m at higher BWPC concentrations, showing a sigmoidal behavior typically described for protein adsorption at air/water interface. The rheological measurement indicated a gradual increase in dilatational modulus (E) over time, indicating an improvement in solid character of the films. In the presence of α-TOC, higher π values were observed which could be attributed to better arrange of complexes at surface than proteins. Rheological measurements showed lower E values with decreasing trend over time, indicating that complexation lead to weak molecular interactions among surface active proteins. In conclusion, the surface activity of BWPC is clearly affected by complexation with α-TOC. Despite vitamin improved the increasing surface pressure, it reduced the solid character of surface films, which may impact on functionality of studied proteins.