Influence of hydrocolloid addition on physical properties and rheology of olive oil in bitter orange juice (O/W) nano-emulsions prepared with blends of different surfactants

Abstract

Olive oil-in-bitter orange juice (O/W) nano-emulsions were prepared by Phase Inversion Composition method. Binary combinations of Tween80, Span20, sucrose monopalmitate and sunflower lecithin were used as surfactants. Influence of type (locust bean gum, xanthan gum, iota-carrageenan) and concentration (0–0.40%) of added hydrocolloid upon physical (visual appearance, transparency (T), microstructure, particle size (D₄₃)) and rheological properties (consistency index (K), flow index (n), apparent viscosity (Ƞ_a) of nano-emulsions were investigated. The lowest D₄₃ (0.143 µm–0.569 µm) and Ƞ_a (2.46–2.51 cp) accompanied with the highest T (47.50–70.65%) were observed in nano-emulsions prepared without hydrocolloid. Significant negative correlation was found between D₄₃, Ƞ_a and T, i.e., hydrocolloid addition increased the Ƞ_a and D₄₃, as well as T loss. The Power Law model was well-suited to the experimental data (R²>0.9534). The n values of Tween80/Span20, Tween80/SL and Tween80/SMP nano-emulsions in the absence of hydrocolloid were 1.00, 0.98 and 0.99, respectively, which presents a Newtonian behavior. The n values of Tween80/Span20, Tween80/SL and Tween80/SMP nano-emulsions in the presence of LBG, XA and i-CARR at varying concentrations were in the range of 0.16–0.99, 0.13–0.98 and 0.15–0.97, respectively, which presents Non-Newtonian shear-thinning behavior. Same type of hydrocolloid showed similar trend in all nano-emulsions regardless of emulsion composition. There has been significant positive correlation between D₄₃, K and Ƞ_a, while there has been significant negative correlation between T, n and Ƞ_a.

Graphical Abstract

Keywords:

• Bitter orange
• hydrocolloids
• nano-emulsion
• rheology
• surfactant

Acknowledgements

The study was carried out with the existing infrastructure of the food engineering department of Gaziantep University without any fund.

Disclosure statement

The authors declare that they have no conflict of interest.