Effect of polyphenolic structure and mass ratio on the emulsifying performance and stability of emulsions stabilized by polyphenol-corn amylose complexes

Fabrication and characterization of emulsion stabilized by tannic acid/soluble potato starch complexes

In this study, the influence of tannic acid (TA)/soluble potato starch (PS) mass ratio and PS concentration on TA/PS complexes and emulsions stabilized by TA/PS complexes were studied. The size, hydrophobicity and emulsifying properties of TA/PS complexes were all controlled by TA/PS mass ratio and PS concentration. In detail, the hydrophobicity of PS (θow = 48°) improved after complexing with TA to form TA/PS complexes (θow max = 64°). The emulsions size decreased and then increased with increasing TA/PS ratio. Additionally, the emulsifying properties of TA/PS complexes improved by increasing PS concentration. Analysis of the interfacial tension after adsorption equilibrium (0.25 mass ratio, TA/PS complexes (13.03 mN/m), TA (14.21 mN/m) and PS (20.25mN/m)), TA and PS had a synergistic effect of stabilizing the oil-water surface. Among them, TA mainly played a role in emulsifying property, and PS mainly played a role of stabilization. All emulsions exhibited obvious creaming. However, at high PS concentration or TA/PS ratio, the creaming was prevented by formed smaller emulsion size, interface complexes networks or high viscosity (Increased from 0.004 to 0.060 Pa.s). It showed that TA/PS complexes can act as emulsifiers to improve the physical and oxidative stability of emulsions, making them suitable for delivering oxidation-sensitive fat-soluble bioactive compounds.

Fabrication of oil-in-water high internal phase emulsions with enhanced antioxidative properties by modified starch/polyphenol mixtures: Effect of EGCG concentration, NaCl concentration, and temperature

In this study, oil-in-water (O/W) high internal phase emulsions (HIPEs) with enhanced antioxidative properties stabilized by octenyl succinic anhydride modified starch (OSAS)/(-)-Epigallocatechin-3-gallate (EGCG) mixtures were prepared. The influence of EGCG concentration (0-0.2 %, w/v), NaCl concentration (0-400 mmol/L), and temperature (25-90 °C) on the stability of the HIPEs was evaluated. The formation of O/W HIPEs, and OSAS/EGCG mixtures formed a thicker barrier on the surface of the oil droplets was confirmed using confocal laser scanning microscopy (CLSM) and cryo-scanning electron microscopy (Cro-SEM), respectively. The results indicated the HIPEs stabilized by OSAS/EGCG mixtures exhibited good environmental stability. All HIPEs displayed excellent antioxidant properties. As the concentration of EGCG in the OSAS/EGCG mixtures was increased from 0 to 0.2 % (w/v), the lipid hydroperoxide (LH) content was reduced from 534.89 mmol/kg oil to 453.77 mmol/kg oil, and malondialdehyde (MDA) content was reduced from 10.15 mmol/kg oil to 6.07 mmol/kg oil. Combined with the effect of NaCl, the oxidative stability was improved further. This study provided a new formulation of food-grade O/W HIPEs with strong antioxidant properties could be a potential solid fat substitute for future foods.

Effect of (-)-epigallocatechin gallate palmitate complexation under mild temperature on the structure and nutritional functions of porous rice starch

The correlation among the hierarchical structure, physicochemical properties, and nutritional functions of porous rice starch after absorbing and complexing with (-)-epigallocatechin gallate palmitate (P-EGCG) under mild temperatures at different reaction times were investigated. The P-EGCG loading rate (19.6 %-28.5 %) of porous starch increased after hydrolysis with a mixture of amyloglucosidase and α-amylase for 3 and 6 h, respectively. A decrease in the melting enthalpy of the amylopectin double helix and an increase in the melting enthalpy of the V-type helices after complexation was observed with longer reaction times. The retention index of P-EGCG after 6 h of incubation was 57.11 % following 21 d of storage. These structural changes significantly transformed portions of the rapidly and slowly digestible starches into resistant starch (41.68 %-47.84 %), accompanied by enhanced thermal stability, antioxidant activity, and enteropathogenic bacteria-inhibiting ability. Therefore, porous rice starch complexed with P-EGCG may provide controlled digestion, antioxidant activity, and potential gut microbiota benefits.

Enhanced stability of curcumin encapsulated in fish gelatin emulsions combined with γ-Polyglutamic acid

This study examined the rheological properties, interfacial characteristics, particle size, zeta potential, Turbiscan stability index (TSI), morphology, and encapsulation efficiency of curcumin (Cur) loaded fish gelatin (FG) emulsions modified with γ-polyglutamic acid (γ-PGA). The results showed that adding γ-PGA significantly increased curcumin encapsulation efficiency. At 0.3 mg/mL, FG emulsions had an encapsulation efficiency of 80.14 %, while FG-γ-PGA emulsions reached 90.35 %. The FG-γ-PGA emulsions also showed enhanced stability and resistance to phase separation, remaining stable for seven days, compared to three days for FG emulsions. After 24 h, the TSI of FG emulsions with 0.6 mg/mL Cur was 2.46, significantly higher than the 0.55 TSI for FG-γ-PGA emulsions at the same concentration. FG-γ-PGA emulsions had smaller droplet sizes, and analysis of interfacial characteristics, particle size, and zeta potential indicated better system stability than FG emulsions. These improved properties of FG-γ-PGA emulsions highlight their potential as efficient carriers for curcumin. Overall, the favorable characteristics of FG-γ-PGA emulsions suggest promising applications in the food industry, especially for developing functional foods with extended shelf life and enhanced nutritional benefits.

Colloidal lignin particle reinforces the stability of Pickering emulsions prepared with zein nanoparticle

Zein nanoparticle (ZNP) is at the forefront of research on Pickering emulsions, valued for its self-assembling and surfactant-free nature. Nevertheless, its emulsion stability is undermined by inadequate amphiphilicity. Colloidal lignin particle (CLP), characterized by its antithetical charge and amphiphilic nature, appears the promising for augmenting the stability of ZNP-based emulsion. This study meticulously investigated the impact of CLP on the colloidal properties and emulsifying performance of ZNP. The results revealed that electrostatic interactions between ZNP and CLP significantly mitigated the charge of ZNP and improved its hydrophilic/lipophilic balance. Under optimized conditions (1.0 wt% particle concentration, pH 4.0, 50% oil content), CLP notably reduced droplet sizes (41-225 μm) and enhanced the stability of ZNP-based Pickering emulsion, particularly at ZNP/CLP ratios of 6:4 and 5:5. In nature, CLP improved the stability ZNP-based Pickering emulsions via increased interfacial adsorption, enhanced steric hindrance, and reinforced viscous structure.

Improving complexation of puerarin with kudzu starch by various ultrasonic pretreatment: Interaction mechanism analysis

The industrial preparation of kudzu starch (KS) significantly reduces the remaining of flavonoids like puerarin (PU) in the product, weakening its biological activity and making pre-treatments on kudzu crucial. Ultrasonic technique, widely used for modifying biomolecules, can enhance nutrient interactions like those between starch and polyphenols in foods. Thus, a puerarin-kudzu starch (PKS) complex was prepared with the introduction of ultrasonic pretreatment. The results indicated that sonication increased the binding of PU to KS from 0.399 ± 0.01 to 0.609 ± 0.05 mg/g. Particle size analysis and SEM revealed that the particles of the ultrasonic puerarin-kudzu starch complex (UPKS) were larger than those of the untreated complexes. XRD, UV-vis, and FT-IR spectroscopic analyses indicated that hydrogen bonding primarily governs the interaction between PU and KS. Additionally, incorporating PU decreased the starch structure's orderliness, while ultrasonic treatment altered the helical configuration of straight-chain starch, leading to the formation of a new, ordered structure through the creation of new hydrogen bonds. Additionally, gels formed from UPKS exhibited higher viscosity, elasticity, and shear stress, suggesting that ultrasound significantly altered the intermolecular interactions between PKS. In conclusion, the use of ultrasound under optimal conditions has demonstrated its effectiveness in preparing PKS complexes, highlighting its significant potential to produce high value-added kudzu-based products.

Effects of dynamic high-pressure microfluidization treatment on the structural, physicochemical, and digestive properties of wheat starch-Lonicera caerulea berry polyphenol complex

Polyphenol complexes can improve the physicochemical and functional properties of starch. In this study, a wheat starch-Lonicera caerulea berry polyphenol complex (WS-LCBP) was prepared using dynamic high-pressure microfluidization (DHPM). The effects of different DHPM pressures (150 and 250 MPa), number of cycles (1 and 3), and LCBP content (0 %, 6 %, 8 %, and 10 %) on the multiscale structure, physicochemical properties, and in vitro digestibility of WS-LCBP were examined. After a single 250 MPa DHPM cycle, Average particle size and water separation rate of WS were reduced by 42.40 % and 16.67 %, the freeze-thaw stability was significantly improved (P < 0.05), and the resistant starch (RS) content 68.67 % was significantly increased (P < 0.05). WS-LCBP has a V-shaped starch structure, which hinders gelatinization and increases enthalpy. The RS content of the WS-LCBP ranged from 72.46 % to 89.09 %, which was significantly higher (P < 0.05) than that of wheat starch subjected to a single 150 MPa DHPM cycle (36.31 %). Three 250 MPa DHPM cycles were beneficial for the formation of WS-LCBP. However, excessive DHPM treatment pressure and frequency reduced the recombination rate of LCBP and wheat starch. This study provides reference data for the industrial production of nutritionally functional wheat-resistant starch using green technologies.

Fabrication of cellulose nanofibers/epigallocatechin gallate complexes: Insights into structure, antioxidant properties and enhanced emulsion performance

In this work, cellulose nanofiber/epigallocatechin gallate (CNF/EGCG) complexes at different ratio were fabricated and the effects on characteristics and stability of emulsions under different oil phase fraction (φ) were investigated. The results of functional groups indicated the formation of CNF/EGCG complexes via hydrogen bond interaction, leading to enhanced antioxidant activity as the proportion of EGCG increased. The complexes exhibited more fragments but pure CNF were more homogenously dispersed in the aqueous phase. Enhancing the EGCG content reduced the droplet size of emulsions firstly before increased, while the apparent viscosity and viscoelastic properties displayed a contrary trend. Emulsion gels with smaller droplet size, higher apparent viscosity, excellent viscoelastic properties and physical stability could be formed at φ = 0.5 while emulsions at φ = 0.3 exhibited slight creaming. The emulsions at lower CNF/EGCG ratio presented better oxidative stability, which was ascribed to the higher antioxidant activity of the complexes and the thicker interfacial film. Results suggest that EGCG could be combined with CNF to improve the emulsion performance and be applied in extending the shelf-life of the emulsion-based products.

Effect of starch categories and mass ratio of TA/starch on the emulsifying performance and stability of emulsions stabilized by tannic acid-starch complexes

This study compounded natural corn starch (CS), mung bean starch (MBS) and potato starch (PS) with tannic acid (TA) to stabilize O/W Pickering emulsion. The effect of TA/starch mass ratio (0-0.25) and three starch categories on particle properties, emulsifying properties, lipid oxidation, freeze-thaw stability, emulsion powder and digestive properties were comprehensibly investigated. In detail, the TA/starch complexes size increased gradually (91.14 nm-200.87 nm) and the hydrophobicity first increased and then decreased (TA/CS > TA/MBS > TA/PS) with increasing TA/starch mass ratio. In addition, the emulsifying ability of TA/starch complexes also increased first and then decreased with increasing mass ratio, especially TA/CS system was the best, which was the same as the hydrophobicity conclusion (θow = 80.46°). Moreover, four starch-based emulsion application characteristics were further evaluated to reveal interface structure. Compared to CS and PS system, TA/MBS emulsion had stronger ability to resist the oil oxidation (TBA = 2.54 μg/mL), destruction of ice crystal (whiter emulsion powder) and digestive enzymes (FFAs = 75.33 %). It mainly attributed to the crosslinking network structure and the highest surface load of TA/MBS complexes. This study would provide new ideas for the design and application of emulsifying properties and emulsion stability.

General approaches to biopolymer-based Pickering emulsions

Pickering emulsion is a type of emulsion that uses solid particles or colloidal particles as emulsifiers rather than surfactants to adhere at oil-water interface. Pickering emulsions have gathered significant research attention recently due to their excellent stability and wide range of potential uses compared to traditional emulsions. Major advancements have been made in development of innovative Pickering emulsions using different colloidal particles by various techniques including homogenization, emulsification and ultrasonication. Use of biopolymer particles gives Pickering emulsions a more escalating possibilities. In this review paper, we seek to present a critical overview of development in food-grade particles that have been utilized to create Pickering emulsions with a focus on techniques and application of Pickering emulsions. Particularly, we have evaluated protein, lipid, polysaccharide-based particles and microalgal proteins that have emerged in recent years with respect to their potential to stabilize and add novel functionalities to Pickering emulsions. Some preparation methods of Pickering emulsions in brief, applications of Pickering emulsions are also highlighted. Encapsulation and delivery of bioactive compounds, fat substitutes, film formation and catalysis are potential applications of Pickering emulsions. Pickering double emulsions, nutraceutical and bioactive co-delivery, and preparation of porous materials are among research trends of food-grade Pickering emulsions.

Effects of conjugated interactions between Perilla seed meal proteins and different polyphenols on the structural and functional properties of proteins

The study aims to perform alkali-induced covalent modification of perilla seed meal protein (PSMP) using different polyphenols: gallic acid (GA), protocatechuic acid (PCA), caffeic acid (CA), apigenin (API) and luteolin (LU). Covalent binding between different polyphenols and PSMP was found to occur, with PSMP-LU showing the highest binding rate of 90.89 ± 1.37 mg/g; the fluorescence spectrum of PSMP-CA showed a maximum blue shift of Δ13.4 nm; the solubility increased from 69.626 ± 1.39 % to 83.102 ± 0.98 %. In order to better understand how these covalent conjugates, stabilize -carotene in emulsions, they were utilized as emulsifiers in an emulsion delivery method. The work further reveals the formation of PSMP-polyphenol conjugates and develops a novel emulsification system to deliver readily decomposable functional factors, providing a potential scenario for the application of PSMP and bioactive conjugates.

Noncovalent interactions between biomolecules facilitated their application in food emulsions' construction: A review

The use of biomolecules, such as proteins, polysaccharides, saponins, and phospholipids, instead of synthetic emulsifiers in food emulsion creation has generated significant interest among food scientists due to their advantages of being nontoxic, harmless, edible, and biocompatible. However, using a single biomolecule may not always meet practical needs for food emulsion applications. Therefore, biomolecules often require modification to achieve ideal interfacial properties. Among them, noncovalent interactions between biomolecules represent a promising physical modification method to modulate their interfacial properties without causing the health risks associated with forming new chemical bonds. Electrostatic interactions, hydrophobic interactions, and hydrogen bonding are examples of noncovalent interactions that facilitate biomolecules' effective applications in food emulsions. These interactions positively impact the physical stability, oxidative stability, digestibility, delivery characteristics, response sensitivity, and printability of biomolecule-based food emulsions. Nevertheless, using noncovalent interactions between biomolecules to facilitate their application in food emulsions still has limitations that need further improvement. This review introduced common biomolecule emulsifiers, the promotion effect of noncovalent interactions between biomolecules on the construction of emulsions with different biomolecules, their positive impact on the performance of emulsions, as well as their limitations and prospects in the construction of biomolecule-based emulsions. In conclusion, the future design and development of food emulsions will increasingly rely on noncovalent interactions between biomolecules. However, further improvements are necessary to fully exploit these interactions for constructing biomolecule-based emulsions.

Waxy maize starch incorporated (-)-epigallocatechin-3-gallate can stabilize emulsion gel and improve antioxidant activity

A food-grade emulsion gel was stabilized using waxy maize starch (WS) incorporated (-)-epigallocatechin-3-gallate (EGCG) at different ratio (from 5 % to 20 %, w/w). The microstructure, rheological behavior, physical stability and antioxidant activity of emulsion gels were investigated using confocal laser scanning microscopy (CLSM), cryo-scanning electron microscopy (cryo-SEM), and rheometer, etc. The results suggested that incorporated EGCG obviously affected the spatial configuration of WS hydrogel. The WS/EGCG hydrogels presented an excellent lipophilic capacity characterized by tightly adhering to linseed oil droplets in the emulsion gels. Moreover, the viscosity, viscoelasticity and physical stability of the emulsion gels stabilized by the WS/EGCG hydrogel matrices were significantly enhanced. The emulsion gel stabilized by the WS/EGCG hydrogel matrix (15 % EGCG) had long-term emulsifying stability because its emulsified phase volume fraction (77.14 %) remained stable for 30 days. Compared with typical natural and synthetic antioxidants in food and pharmaceutical processing, the emulsion gels stabilized by the WS/EGCG hydrogel matrices showed significant stronger DPPH (97.45 %) and ABTS•+ (97.97 %) free radical scavenging activity. These results demonstrate that WS/EGCG hydrogels can not only be used in food-grade matrix materials to stabilize emulsion gels but also improve the antioxidant activity of the emulsion gels.

Pickering emulsions prepared using zein-sugarcane leaves polyphenol covalent crosslinking nanoparticles via ultrasonication: Capacities in storage stability, lipid oxidation, in vitro digestion and safety evaluation

This study firstly used sugarcane leaf polyphenols (SGLp) to modify zein to form covalent nanoparticles (SGLpZ) and used SGLpZ as an emulsifier to stabilize pickering emulsions (SZP) via ultrasonic method. The results showed that the addition of SGLp could alter the physicochemical properties of zein, including improving increasing the hydrophilicity of zein and the antioxidant properties of zein (three basic antioxidant activities test in vitro). SGLpZ could be able to form a dense film on the surface of the pickering emulsions which inhibited lipid oxidation as the concentration of SGLp increased at 4 ℃ for 20 days, thus stabilizing pickering emulsions (SZP). Further assessment of storage stability of pickering emulsions stabilized by SGLp was evaluated via measuring the free fatty acids (FFA) release in vitro gastrointestinal digestion. The results showed that the FFA release of SZP decreased from 20.61 ± 0.10% to 16.14 ± 0.69%. In addition, SGLp gave SZP a yellow color, which inspired that SZP could be used in the food industry to make yellow-colored functional foods. Finally, the safety of SZP initially assessed by in-vitro hemocompatibility and cytotoxicity (MTT) assays. In conclusion, our fingdings were beneficial for the further design and development of SGLp in food fields and enabled the development a new type in functional protein-plant polyphenols food pickering emulsions.