Structure-rheology relationship of basil seed gum-whey protein isolate mixture: Effect of thermal treatment and biopolymer ratio

Abstract

In this paper, the changes in some physicochemical properties of basil seed gum: whey protein isolate (BSG: WPI) blends were investigated and their correlation with the rheological properties was assessed under different biopolymers ratio and temperatures. To simplify the discussion, total 36 generated rheological parameters were clustered in five groups. Subsequently, the effect of biopolymers ratio (1:0, 1:4 & 1:9 BSG: WPI) and thermal treatment (25 °C & 80 °C for 30 min) were discussed on one parameter from each category. Furthermore, the intensity of the amide I and amide II bands and the percentage area of the curve fitting at around 1632, 1649 and 1683 cm−1 were assessed at different conditions. Generally, heating improved the rheological properties of 1:4 BSG: WPI. Regarding the percentage of 1683 cm−1 band area of different samples, WPI in blends showed lower formation of intermolecular antiparallel β-sheets than in pure WPI dispersion. Also, a partial conversion of β-sheet into α-helix/unordered structure happened at low added BSG blend, i.e., 1:9 BSG: WPI dispersion, whereas, at higher BSG content, i.e., 1:4 BSG: WPI dispersion, β-sheet remained as the main structure of WPI. Unheated and heated 1:4 BSG: WPI showed a lower antagonistic behavior based on apparent viscosity (50 s−1) than 1:9 BSG: WPI. In addition, both blends showed lower antagonistic behavior after heating. Results proposed that different temperatures and biopolymer ratios of BSG: WPI can be utilized to create products that exhibit a variety of different rheological and physicochemical characteristics.