Development of wet media milled purple sweet potato particle-stabilized pickering emulsions: The synergistic role of bioactives, starch and cellulose

Effect of wet media milling on starch-quercetin complex: Enhancement of Pickering emulsifying ability and oxidative resistance

This research explored the effect of media milling on complexation of corn starch (CS) and quercetin (QC), interaction mechanism and Pickering emulsifying ability of corn-quercetin (CS-QC) complex. CS-QC with QC/CS ratio of 1:24 had the highest encapsulation efficiency of 76.00 ± 1.30 %. Average volume-mean diameter, average whole molecular size (Rh) and debranchedamylopectinchain length of CS-QC were significantly decreased after milling. Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) spectra confirmed the complexation between CS and QC. Emulsifying capacity and emulsion stability of Pickering emulsion stabilized by 5 % CS-QC complex particles after 120 min milling reached 100.00 % and 100.00. Pickering emulsions stabilized by these complex particles demonstrated superior oxidative stability. These results demonstrated that media milling could be an efficient physical approach to obtain starch-polyphenol complex by enhancing non-covalent interactions, which could not only be used as food-grade Pickering emulsifiers, but also retard lipid oxidation.

Pickering emulsion stabilized by quercetin-β-cyclodextrin-diglyceride particles: Effect of diglyceride content on interfacial behavior and emulsifying property of complex particles

This research develops diacylglycerol (DAG) based Pickering emulsions with enhanced oxidative stability stabilized by self-assembled quercetin/DAG/β-cyclodextrin (β-CD) complexes (QDCCs) using a one-step agitation method. Influence of DAG content (5%, 15%, 40%, and 80%, w/w) on the self-assembly behavior, interfacial properties, and emulsifying ability of complex particles was investigated. SEM, XRD and ATR-FTIR studies confirmed the formation of ternary composite particles. QDCCs in 80% DAG oil had the highest quercetin encapsulation efficiency (6.09 ± 0.01%), highest DPPH radical scavenging rate and ferric reducing antioxidant property (FRAP). β-CD and quercetin adsorption rates in emulsion with 80% DAG oil were 88.4 ± 2.53% and 98.34 ± 0.15%, respectively. Pickering emulsions with 80% DAG had the smallest droplet size (8.90 ± 1.87 μm) and excellent oxidation stability. This research develops a novel approach to regulate the physicochemical stability of DAG-based emulsions by anchoring natural antioxidants at the oil-water interface through a one-pot self-assembly method.

In vitro digestion and colonic fermentation characteristics of media-milled purple sweet potato particle-stabilized Pickering emulsions

BACKGROUND

Pickering emulsions stabilized by multicomponent particles have attracted increasing attention. Research on characterizing the digestion and health benefit effects of these emulsions in the human gastrointestinal tract are quite limited. This work aims to reveal the digestive characteristics of media-milled purple sweet potato particle-stabilized Pickering emulsions (PSPP-Es) during in vitro digestion and colonic fermentation.

RESULTS

The media-milling process improved the in vitro digestibility and fermentability of PSPP-Es by reaching afree fatty acids release rate of 43.11 ± 4.61% after gastrointestinal digestion and total phenolic content release of 101.00 ± 1.44 μg gallic acid equivalents/mL after fermentation. In addition, PSPP-Es exhibited good antioxidative activity (2,2-diphenyl-1-picrylhydrazyl and ferric reducing antioxidant power assays), α-glucosidase inhibitory activity (half-maximal inhibitory concentration: 6.70%, v/v), and prebiotic effects, reaching a total short-chain fatty acids production of 9.90 ± 0.12 mol L-1, boosting the growth of Akkermansia, Bifidobacterium, and Blautia and inhibiting the growth of Escherichia-Shigella.

CONCLUSIONS

These findings indicate that the media-milling process enhances the potential health benefits of purple sweet potato particle-stabilized Pickering emulsions, which is beneficial for their application as a bioactive component delivery system in food and pharmaceutical products. © 2024 Society of Chemical Industry.

In vitro gastrointestinal digestion and colonic fermentation of media-milled black rice particle-stabilized Pickering emulsion: Phenolic release, bioactivity and prebiotic potential

This is a pioneer study that investigated the digestive characteristics of Pickering emulsions stabilized by media-milled black rice particles during in vitro digestion and colonic fermentation. Free fatty acid release of the emulsions improved from 28.42 ± 3.13% to 33.68 ± 4.05% after media milling. The phenolics released from media-milled sample were close to those from unground sample. Media-milled sample exhibited higher DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging ability and α-glucosidase inhibition rate than unground sample. Media milling increased the generation of short-chain fatty acids (SCFAs) during colonic fermentation, especially acetic acid (23% improvement in media-milled sample over unground sample). It also inhibited the growth of harmful bacteria namely Escherichia Shigella and Streptococcus, and promoted the growth of beneficial bacteria including Bifidobacterium and Blautia. These findings revealed that media-milled black rice particle-stabilized Pickering emulsions possessed intrinsic bioactivity and prebiotic potentials in the gastrointestinal tract for the first time.

Media-milled agar particles as a novel emulsifier for food Pickering emulsion

Pickering emulsions was successfully fabricated using ball-milled agar particles with sizes and sulfate content around 7 μm and 0.62 %, respectively. These particles were obtained through a simple media-milling process using agar powders initially sized at 120 μm. The lamellated agar is aggregated into a mass after the milling process. The surface charge and hydrophobicity of the ball-milled agar particles were characterized through zeta potential and contact angle measurements, respectively. The droplet size of Pickering emulsions was related to oil fraction and particle concentration, ranging from approximately 45 μm to 80 μm. Ball-milled agar stabilized emulsions were sensitive to pH and salt conditions. The results of confocal laser scanning microscopy and cryo-SEM showed that at low particle concentrations and oil fractions, ball-milled agar stabilized the emulsions by dispersing particles on the surface of the oil droplets through electrostatic repulsion. Conversely, ball-milled agar stabilized the emulsions under high particle concentrations and oil fractions by forming a gel network structure to bind the oil droplets. In this research, this developed method provides the basis for the high-value application of agar and a new idea for preparing stable food-grade Pickering emulsion-based functional foods using raw-food material without surface wettability.

Stabilization of High Internal Phase Oil-in-Water Emulsions Using "Whole" Gracilaria lemaneiformis Slurry

In this study, a Gracilaria lemaneiformis slurry (GLS) was prepared using low-energy mechanical shearing. The resulting GLS, which was rich in polysaccharides, was utilized as an effective stabilizer for oil-in-water emulsions. The microstructures and stability of the resulting emulsions were controlled by adjusting the emulsion formulations, including Gracilaria lemaneiformis (GL) mass concentration and oil volume fraction (φ). The optimized GL mass concentration and φ conditions yielded high internal phase emulsions (HIPEs) with gel-like textures. Moreover, the presence of exogenous Ca2+ resulted in bridging structures in the emulsions, enhancing their viscoelasticity and forming a robust physical barrier against droplet coalescence. Our findings highlight the effectiveness of the GLS as an emulsifier for stabilizing HIPEs. Notably, this method relies solely on physical processes, aligning with the desirability of avoiding chemical additives, particularly in the food industry.

Starch physical treatment, emulsion formation, stability, and their applications

Pickering emulsions are increasingly preferred over typical surfactant-based emulsions due to several advantages, such as lower emulsifier usage, simplicity, biocompatibility, and safety. These types of emulsions are stabilized using solid particles, which produce a thick layer at the oil-water interface preventing droplets from aggregating. Starch nano-particles (SNPs) have received considerable attention as natural alternatives to synthetic stabilizers due to their unique properties. Physical formulation processes are currently preferred for SNP production since they are environmentally friendly procedures that do not require the use of chemical reagents. This review provides a thorough overview in a critical perspective of the physical processes to produce starch nano-particles used as Pickering emulsion stabilizers, fabricated by a 2-step process. Specifically, the reviewed physical approaches for nano-starch preparation include high hydrostatic pressure, high pressure homogenization, ultrasonication, milling and antisolvent precipitation. All the essential parameters used to evaluate the effectiveness of particles in stabilizing these systems are also presented in detail, including the hydrophobicity, size, and content of starch particles. Finally, this review provides the basis for future research focusing on physical nano-starch production, to ensure the widespread use of these natural stabilizers in the ever-evolving field of food technology.

Thermomechanically micronized sugar beet pulp: Emulsification performance and the contribution of soluble elements and insoluble fibrous particles

In this work, thermomechanically micronized sugar beet pulp (MSBP), a micron-scaled plant-based byproduct comprised of soluble elements (∼40 wt%) and insoluble fibrous particles (IFPs, ∼60 wt%), was used as a sole stabilizer for oil-in-water emulsion fabrication. The influence of emulsification parameters on the emulsifying properties of MSBP was investigated, including emulsification techniques, MSBP concentration, and oil weight fraction. High-speed shearing (M1), ultrasonication (M2), and microfludization (M3) were used to fabricate oil-in-water emulsions (20% oil) with 0.60 wt% MSBP as stabilizer, in which the d_4,3 value was 68.3, 31.5, and 18.2 μm, respectively. Emulsions fabricated by M2 and M3 (higher energy input) were more stable than M1 (lower energy input) during long-term storage (30 days) as no significant increase of d_4,3. As compared to M1, the adsorption ratio of IFPs and protein was increased from ∼0.46 and ∼0.34 to ∼0.88 and ∼0.55 by M3. Fabricated by M3, the creaming behavior of emulsions was completely inhibited with 1.00 wt% MSBP (20% oil) and 40% oil (0.60 wt% MSBP), showing a flocculated state and could be disturbed by sodium dodecyl sulfate. The gel-like network formed by IFPs could be strengthened after storage as both viscosity and module were significantly increased. During emulsification, the co-stabilization effect of the soluble elements and IFPs enabled a compact and hybrid coverage onto the droplet surface, which acted as a physical barrier to endow the emulsion with robust steric repulsion. Altogether, these findings suggested the feasibility of using plant-based byproducts as oil-in-water emulsion stabilizers.

Fabrication of Antioxidant Pickering Emulsion Based on Resveratrol-Grafted Zein Conjugates: Enhancing the Physical and Oxidative Stability

Lipid oxidation is still a major problem complicating the development of food emulsions. In this study, an antioxidant Pickering emulsion stabilized by resveratrol-grafted zein (Z-R) conjugates and pectin (P) complex particles was prepared. The hydrophilic pectin successfully adjusted the wettability of Z-R; when the mass ratio of Z-R to P was 2:1 (Z-R/P2:1), the three-phase contact angle was 90.68°, and the wettability of the particles was close to neutral. Rheological analysis showed that the emulsion formed an elastic gel structure. FTIR spectra indicated that there was a hydrogen bond and electrostatic interaction between Z-R and P. The disappearance of characteristic infrared peaks of corn oil was due to a dense protective film formed on the surface of oil drops by Z-R/P2:1 particles, which was confirmed by confocal laser scanning microscopy. The emulsion stabilized by Z-R/P2:1 had excellent physical stability at a wide range of pH values (4-9), salt ion concentrations (0.04-0.15 mol·L-1) and storage times (0-30 days). The anti-lipid oxidation ability of the emulsion was outstanding; after storage for 14 days at room temperature, the MDA content in the emulsion was only 123.85 μmol/kg oil. In conclusion, the Z-R/P2:1 particles prepared in this study can effectively stabilize a Pickering emulsion and expand the usability of the method for constructing antioxidant Pickering emulsions.

The Fabrication and Characterization of Pickering Emulsion Gels Stabilized by Sorghum Flour

Pickering emulsion gels have potential application as solid fat substitutes and nutraceutical carriers in foods, but a safe and easily available food-derived particle emulsifier is the bottleneck that limits their practical application. In this study, the function of sorghum flour as a particle emulsifier to stabilize the oil-in-water (O/W) Pickering emulsion gels with medium chain triglycerides (MCT) in the oil phase was introduced. Sorghum flour had suitable size distribution (median diameter, 21.47 μm) and wettability (contact angle, 38°) and could reduce the interfacial tension between MCT and water. The oil phase volume fraction (φ) and the addition amount of sorghum flour (c) had significant effects on the formation of Pickering emulsion gels. When c ≥ 5%, Pickering emulsion gels with φ = 70% could be obtained. Microstructure analysis indicated that sorghum flour not only played an emulsifying role at the O/W interface but also prevented oil droplets from coalescing through its viscous effect in the aqueous phase. With increases in c, the droplet size of the emulsion gel decreased, its mechanical properties gradually strengthened, and its protective effect on β-carotene against UV irradiation also improved.