Lignins interfacial behavior tailored by formulation parameters

Abstract

Present work focuses on the understanding of lignins’ capacity to adsorb at the oil–water interface depending on both their concentration and particles size. To this purpose, the premise was that it should be possible to control lignins emulsifying capacities by modulation of both oil content and lignins content as well as particles size. In a first step, interfacial behavior of lignins dispersions was characterized through both interfacial tension and interfacial rheology. This allowed evidencing a strong ability to reduce oil–water interfacial tension, with an interfacial value going up to 1 mN/m. In addition, the occurrence of interfacial viscoelastic properties was established, with interfacial moduli values 1000 times higher than when no lignins were present in the dispersion, and with very different structuring kinetics depending on the characteristics of lignins. Then, corresponding emulsifying properties in the presence of sweet almond oil were investigated. High energy input for emulsification process allowed getting better lignins adsorption at the interface, explained by the decrease of lignins particles size, leading to a more homogeneous, and stable emulsion. Results showed that lignins have a strong emulsifying capacity as they could emulsify up to 60 % w/w of sweet almond oil and form stable concentrated O/W emulsions.