Interaction of whey protein isolate and natural deep eutectic solvents: Effect on conductivity, surface tension, stability, and flow behaviour

Abstract

The present study aimed to understand the structural–functional relationships between whey protein isolate (WPI) and natural deep eutectic solvents (NADES) dispersion. Lactic acid, malic acid, glucose, and fructose-based NADES were used with 2.5 and 5 % WPI. WPI dispersion with lactic acid and malic acid NADES showed low pH, surface tension, thermal stability with high conductivity, and foam stability. On the other hand, WPI with glucose and fructose NADES showed the opposite behaviour to acid NADES. In FTIR, WPI and NADES were shown to have a substantial interaction. The dispersion of sugar NADES showed higher peak force and energy than acid NADES. The dispersion showed Newtonian as well as non-Newtonian flow behaviour. The dispersion with sugar showed non-Newtonian behaviour as n < 1; however, acid based WPI dispersion showed Newtonian as well as non-Newtonian flow behaviour. Therefore, the present study demonstrated a tailoring approach for WPI dispersion according to the purpose of use.