Characterization and enhanced functionality of nanoparticles based on linseed protein and linseed gum biocomplexes.

The formation, characterization, and functionality of hybrid nanoparticles based on linseed bio-macromolecules extracted as linseed protein (LP) and linseed gum (LG) from the remaining meal after oil extraction were investigated. The assembly of bioparticles at different protein to polysaccharide ratios as a function of pH was characterized in terms of absorbance measurements, dynamic light scattering and surface charge. The wettability of the assembled particles as well as the plain LP and LG was also determined. By increasing the LG proportion in the bioparticles, both the size of the particles and their contact angle tended to decrease, whereas their zeta potential became more negative over the whole studied pH range. The formed negatively charged particles at pH 3 with a 50:50 LP to LG ratio and a size of approximately 300 nm were selected and their functional properties (solubility, emulsifying and foaming properties) were compared to the individual biopolymers. The interaction between LG and LP was found to modify the functional properties of native LP especially at and around its isoelectric point. The LP-LG particles could be useful for stabilizing plant-based emulsions and foams.

Maillard conjugation of whey protein isolate with water-soluble fraction of almond gum or flaxseed mucilage by dry heat treatment.

The Maillard conjugation of whey protein isolate (WPI) by dry heat treatment (74% relative humidity at 60 °C) to either the water-soluble fraction of almond gum (SFAG) or flaxseed mucilage (SFM) was compared. Depending on the protein to polysaccharide ratio, carbohydrate type, and incubation time, different degrees of substitutions of the amino groups were obtained. The characterization of the conjugates by TNBS, SDS-PAGE, size exclusion chromatography, and circular dichroism analysis confirmed the formation of conjugates. SFAG was found to have less tendency for the formation of grafted WPI than SFM, which could be attributed to both the polysaccharide composition and/or a higher molecular weight. Ultimately, the emulsions stabilized by conjugates (pH 5.0 and 6.5) remained homogenous with no droplet size variation after heating, indicating that the conjugation of WPI to SFAG and SFM substantially improved its heat stability.

Effect of thymol and Pickering stabilization on in-vitro digestion fate and oxidation stability of plant-derived flaxseed oil emulsions.

The aim of this study was to evaluate the effect of Pickering stabilization by biopolymer-based particles (bioparticles), consisting of flaxseed protein and polysaccharides, and of the addition of thymol to the oil phase on the oxidation stability, and digestion fate of flaxseed oil (FO) emulsions, compared to bulk FO and conventional emulsions stabilized by polysorbate 80 (PS80). Applying Pickering stabilization and thymol simultaneously was a successful approach to retard FO oxidation. Moreover, lipid digestion was slower in bioparticle-stabilized emulsions compared to PS80 stabilized emulsions. The thymol bioaccessibility increased after incorporation into FO Pickering emulsions in comparison to the bulk oil. The results suggested that the combination of Pickering stabilization and thymol addition to the oil phase can be used as a promising way of protecting highly unsaturated oils such as FO against oxidation. These emulsions are also applicable for designing functional foods with controlled lipid digestion.

Bioparticles of flaxseed protein and mucilage enhance the physical and oxidative stability of flaxseed oil emulsions as a potential natural alternative for synthetic surfactants.

Flaxseed protein (FP) and mucilage (FM) complex bioparticles as sustainable ingredients were assembled by electrostatic interaction for plant-based Pickering stabilization of flaxseed oil (FO)-in-water emulsions. The effect of FO content (1-5 wt%) on droplet size and accelerated creaming stability of the emulsions was evaluated, from which it was found that 2.5 wt% FO emulsion had the smallest initial droplet size (i.e. D[4,3] = 8 µm) and creaming velocity (2.9 µm/s). The microstructure of the emulsions was observed using Cryo-SEM, confocal and optical microscopy, showing a thick layer of the particles on the oil surface responsible for the stabilization. The physical stability of FO emulsions stabilized by complex bioparticles against various environmental stress conditions (pH, salt and temperature) was higher compared to plain FP- and polysorbate 80-stabilized emulsions. Thus, the droplet size of FP-stabilized emulsions (pH 3) increased from 21 to 38 µm after thermal treatment (80 °C), whereas the size distribution of particle-stabilized emulsions hardly changed. The latter emulsions also remained stable during 28 days of storage and displayed good stability against a wide range of pH conditions (2-9) and salt concentrations (0-500 mM) with no sign of oiling-off. The complex particles as Pickering emulsifiers were successful to depress the FO oxidation at 4 °C and 50 °C. This study could open a promising pathway for producing natural and surfactant-free emulsions through Pickering stabilization using plant-based biopolymer particles for protecting lipophilic bioactive components.

Stability assessment of conjugated linoleic acid (CLA) oil-in-water beverage emulsion formulated with acacia and xanthan gums.

The development of a conjugated linoleic acid (CLA) oil-in-water beverage emulsion containing acacia gum (AG) and xanthan gum (XG) was investigated. D-optimal design and response surface method was used and 10% w/w AG, 3.5% w/w CLA and 0.3% w/w XG was introduced as the optimum formula. Afterward the effect of storage time on the physicochemical properties of selected formulation including specific gravity, turbidity, viscosity, average droplet size, span, size index, creaming index, oxidation measurements and stability in its diluted form, were determined. Findings revealed that the size of oil droplets increased after six weeks and resulted in instability of the emulsion concentrate. Peroxide value increased until 21 days and then decreased dramatically, whereas TBA and Totox values began to increase after this time. Turbidity loss rate was low demonstrating the good stability of the diluted emulsion. The results revealed that it is possible to produce a stable CLA oil-in-water emulsion for using in beverages.